E. I. Androsova, Zoological Institute, Russian Academy of Sciences, St. Petersburg, 199034, Russia
The bryozoan fauna of the Arctic Ocean within Russian borders is rather well-described in the publications of Prof. G. A. Kluge (1962 etc), and faunas of the White and Barents Seas are described in publications of M. G. Gostilovskaya (1978 etc) and N. V. Denisenko (1990) respectively. These data permit comparison of the Bryozoa of the two seas. Bryozoan diversity in the White Sea is less than the Barents Sea: about 300 species are presently known from the Barents Sea compared with only 145 from the White Sea. A similar pattern occurs in other groups of invertebrates and in fishes. Of the 145 bryozoan species found in the White Sea, only 6 have not been found in Barents Sea also. Two of these six are conditional endemics, and one - Porella tumida Kluge, 1955 - has been found by us only at the neck of the White Sea . The other three species are Proboscina fecunda Kluge, 1962, Tubulipora aperta Harmer, 1898 and Bugulopsis peachi var.beringia Kluge, 1952. One of the factors causing the decrease of Bryozoa in The White Sea is the extreme character of its neck which acts as an ecological barrier. This part of the White Sea is so peculiar that K. M. Derjugin (1928) compared it to a river. Continuous turnover of deep waters to the surface causes homothermia and homosalinity, rapid currents effect the substratum, and high amplitudes of daily and seasonal temperature variations make conditions difficult for living organisms including Bryozoa. The neck is a real ecological barrier which hinders faunal exchange between the Barents and White Seas.
The bryozoan fauna of both seas is formed mainly of Boreal-Arctic eurybiont species which are adapted to the environmental conditions. These species form 66% of the White Sea fauna and about 50% of the Barents Sea fauna. However, the proportion of Arctic species in the White Sea is less than in the Barents Sea: 19% and 26.5% respectively. A greater difference is found in the Boreal species: 15% and 24% respectively. It is to be noted that among 7 amphiboreal species of the White Sea, 5 have been found in the neck. These include the very rare species Porella tumida Kluge, 1955, described by Kluge from the Bering Strait and found in the neck of the Barents Sea for the first time by us.
Yu. A. Borisenko, Geology and Geography Department, Char'kov State University, Dzerzhinskiy Square, 4, Char'kov, 310077, Ukraine; and V. I.Gontar, Laboratory of Marine Research, Zoological Institute of RAS, University Quay, 1, St Petersburg, 199034, Russia
The taxonomy of the Bryozoa is incomplete, and criteria for describing higher taxa are varied and often subjective. Very little attention has been paid to microstructure and the composition of the bryozoan skeleton and its phylogenetic importance. Therefore, analysis of mineralogical peculiarities of cheilostome bryozoans is suggested as a potentially important taxonomic character. On the basis of our own analyses and data in the literature on the mineralogical composition of different taxa we have shown the following patterns of distribution of mineralization types in taxa of cheilostome bryozoans. It is highly probable that the more primitive bryozoans among both the Anascina and Ascophorina have only calcitic skeletons, whereas evolutionary advanced bryozoans change their skeletal composition from calcite to aragonite, including intermediate forms with different proportions of these two minerals which may be termed bimineralic. Considering the insufficient level of mineralogical study of bryozoan colonies, we can characterize the mineralogical compositions only of large taxa, for example superfamilies, although in many cases it is possible to obtain accurate characteristics for individual families.
(POSTER)
Caroline J. Buttler, National Museums & Galleries of Wales, Cathays Park, Cardiff CF1 3NP, Wales, U.K.; and Patrick N. Wyse Jackson, Department of Geology, Trinity College, Dublin 2, Ireland
The Tramore Limestone crops out on the south-east coast of Ireland in County Waterford. It is a muddy nodular limestone reaching 80 m at its thickest, and ranges in age from Llandeilo to Lower Caradoc. Bryozoans are found in the Tramore Limestone: colonies with a distinct hemispherical dome-shaped morphology are commonly identified. The zoaria range in diameter from 15 mm to 75 mm and have previously been identified as Monticulipora species. Unfortunately the majority of zoaria are re-crystallised making identification difficult. There are some specimens in which the internal structures remain. Examination of these have shown them all to be Diplotrypa (possibly D. petropolitana). The colonies are all abraded and some have Trypanites borings on the upper surface. The lower surface of the colonies are rugose and sometimes concave. Some dome-shaped colonies are asymmetrical in shape perhaps indicating that growth was on a slope or away from adjacent colonies. The bryozoan fauna is not monospecific: decalcified bryozoans of undetermined ramose trepostome forms have been identified. The Tramore Limestone also contains trilobites and a diverse brachiopod fauna which has been shown to have affinities with Baltica.
Roger J. Cuffey, Department of Geosciences (Deike Building), Pennsylvania State University, University Park, PA 16802,USA
Analyses of the earliest known bryozoan reefs, as well as of non-reefal Ordovician bryozoan faunas, make it possible now to infer certain generalities about the unusual bryozoan taxa responsible for building these exotic biohermal structures.
These earliest bryoherms are mid-Early Ordovician (late Tremadocian, China)and early Mid-Ordovician (Chazyan and basal Blackriveran, North America),and are small crust-mounds, composed of laminar to massive trepostome cruststone, bindstone, and bafflestone cores, sometimes flanked by rudstones consisting of broken branching trepostomes. The oldest is near Yichang (Zhu et al. 1993-95; Zhu and Cuffey, in progress). The American-Canadian ones are at Mingan Islands (Desrochers and James 1989; Bolton and Cuffey, in press), Ile Bizard (Kobluk 1981), Lake Champlain (Pitcher 1964-71; Ross 1962-84), Sinking Spring (Pitcher 1964), Knoxville (Walker et al. 1973-82), Birmingham (Stock et al.1981-86), and Chickasaw (Cuffey and Cuffey 1994-95).
Unlike hermatypic corals, reef-building bryozoans remained small, like their non-reefal counterparts, thus indicating no involvement with symbiotic zooxanthellate algae. Instead, strong or sturdy skeletal morphologies may have enabled or "pre-adapted" certain trepostomes for constructing the first bryoherms, in preference over weaker-built contemporary taxa.
In all of the earliest bryozoan reefs, the most important frame-builders were batostomids (in North America, especially Batostoma chazyensis; in China, an as-yet-undescribed species). In this family, the individual zooecia are surrounded by many large mesopores full of closely-spaced diaphragms, which would have provided greater-than-usual mechanical strength against waves and currents, especially when coupled with low-standing encrusting to massive colony forms.
In certain reef mounds, dianulitids (Dianulites) are also significant frame-builders. Likewise with encrusting to massive colonies, these forms additionally have unusually large-diameter zooecial tubes, packed tightly together, suggestive of certain strengthening-type "cellular" architecture in modern buildings.
Simultaneously, another trepostome - in North America the atactotoechid Champlainopora chazyensis - grew prolifically on the sides of some of these earliest bryoherms. This species had narrow branches, small thin-walled zooecia, and few diaphragms - overall a rather fragile architecture, and now found as reef-flanking piles of branch fragments apparently broken up by water turbulence around the bryozoan mounds.
As the Ordovician wore on, species from other taxa began to contribute to later bryozoan-reef-core construction (Amplexopora, Diplotrypa, Monticulipora, Stigmatella among trepostomes, plus the ceramoporoid Ceramoporella). Soon, however, compact crust-mounds were progressively replaced by more open frame-thickets, and this earliest phase of bryozoan reef building came to a close.
N. V. Denisenko, Murmansk Marine Biological Institute, RAS, Vladimirskaya str., 17, Murmansk, 183010, Russia
This presentation is based on material collected from 10 stations during the expedition of the German RV "Polarstern" to the north of the Spitsbergen archipelago in 1991, supplemented by comparison with previous data. Qualitative samples, collected with Otter and Agassiz Trawls at 6 stations, were transported to MMBI for analysis, while the remaining bryozoan samples were sent to the Zoological Institute, RAS (St. Petersburg) and identified by V. I. Gontar (1995). Altogether, 35 bryozoan species and subspecies were identified in the samples. Only eight, one and eight species were found in the western, middle and south-eastern stations respectively. However, in the north-eastern part, where the samples were collected from a small area, the fauna was investigated in more detail and 31 species were found to be present. Eighteen of these species were found in one particular study area: Diplosolen intricarius,D. obelia var. arctica, Hornera pseudolichenoides,Alcyonidium gelatinosum var. anderssoni, A. radicellatum, Lichenopora verrucaria, Carbasea carbasea, Dendrobeania pseudomurrayana, D. pseudomurrayana var. fessa, Phylactellalabiata, Parasmittina jeffreysi, Smittina glaciata, Pseudoflustra birulai, Porella minuta, P. compressa, Myriapora subgracilis, smitti, Sertella septentrionalis, S. beaniana, S. beaniana var. watersi, Rhamphostomella bilaminata, and Escharoides bidencapi. The total number of bryozoans now known for the study area, including data from a previous study (Gostilovskaya 1964),numbers 46 species and 8 subspecies.
An analysis of bryozoan distribution in the Arctic Ocean in relationship to environmental conditions has shown that the bryozoan fauna is most diverse at depths of 200-250 metres adjacent to the slope edge (Scientific Cruise Report 1992), where the current velocity is the highest, and where the amount of coarse rock material in the bottom sediments (gravel and pebbles) prevails over other fractions. Within the northern seas, in the offshore shelf zone, maximum bryozoan species richness is recorded at depths of 100-150 metres (Gontar and Denisenko 1989; Denisenko 1990). A biogeographical analysis of the bryozoan fauna of theinvestigated stations shows that this group consists of Boreal-Arctic, widespread and circumpolar species. Arctic forms prevail over species of Boreal origin. A comparison of our data with data collected in the 1950s reveals that Boreal-Arctic forms generallyprevail over other groups and Boreal species are very rare. Nevertheless, in spite of insufficient study of the bryozoan fauna, the available data testify to some influence of warm Atlantic waters on the biogeographical structure of the group. Notwithstanding the high latitudes here - as with the large areas of the Barents Sea and around Franz-Josef Land, Boreal forms are present. These penetrate under the influence of the warm Atlantic waters.
N. V. Denisenko, Murmansk Marine Biology Institute, Karelian Scientific Centre, RAS, Vladimirskaja, 17, Murmansk, 183010, Russia
Benthic surveys carried out by the Murmansk Marine Biology Institute in the Pechora Sea during 1992-3 obtained new data on the bryozoan fauna of this region and allowed analysis of its ecology and biogeography. Examination of the samples has revealed 120 bryozoan species and subspecies, twice as many as were previously known (Gostilovskaya 1984; Denisenko 1990). Forty-seven species were noted from this region for the first time. Previously a smaller number of bryozoan species had been recorded for this region of the Barents Sea compared with other regions, determined primarily by the lack of suitable substrates for colonies. Four taxocenes [??] of bryozoans have been distinguished on the basis of cluster analysis using Soerentsen similarity coefficients to compare species lists for each station. The location of each taxocene [??] correlates well with environmental conditions. Species distributions are restricted by the nature of the bottom sediments, in turn determined by bottom relief and related water dynamics. Analysis of the biogeographic structure of the bryozoan fauna of the Pechora Sea does not contradict previous studies (Denisenko 1990) which found that boreal-arctic species are predominant over the entire area. These constitute over 68% of species, a substantial proportion of which belong to widespread species of Pacific origin. The proportion of boreal and arctic bryozoan species for the region as a whole is 12% and 20 % respectively. The proportion of boreal species is comparatively constant over the entire studied area, whereas the proportion of arctic species varies considerably and is lowest(6%) in the shallow and most thoroughly heated southern area of the Pechora Sea. In general, bryozoan biomass in this area is not high. Maximum biomass (10 gms per square metre) was recorded in the southern part of the Pechora Sea at the outlet of Pechora Bay. In other areas of the Pechora Sea biomass does not exceed 2 gms per square metre. Higher values of bryozoan biomass in the southern part of the sea are associated with regions rich in organic suspended matter (carried by the flow of the Pechora River) which is used by bryozoans as food.
Klaus H. Eiserhardt, Geologisch-Palaeontologisches Institut und Museum, Universität Hamburg, Bundesstraße 55, D-20146 Hamburg, Germany
Encrusting base material of erect fossil Cheilostomata is only poorly known. If present, it is most often disregarded because of its atypical skeletal growth. In contrast to this, the present study takes into consideration rich base material of Upper Cretaceous onychocellids. Aspects of skeletal growth, intracolony variation, and astogeny will be presented and discussed in respect to the classification of anascan Cheilostomata.
Tatjana A. Favorskaya, All-Russian Scientific Research Geological Institute (VSEGEI), 74 Sredniy pr., St Petersburg 199026, Russia
Two new Paleocene bryozoan localities were discovered some years ago. The first one (Lower Paleocene) is located near Lusanovka village, Cherkassk district, central Ukraine. Zoarial fragments and nanoplankton (NP2) were found in a limestone from the lower part of a section revealed by borehole No. 1(Moroz & Sovjak-Krukovskiy 1993). The following bryozoans are described here: (1) Crassicellepora voigti Berthelsen; (2) Puncturiella (Puncturiellina) subsculpta Voigt; (3) Hemistylus dissimilis Voigt; (4) Diplobeisselina nobilis (Levinsen); (5) Schizmiellopsis anhaltina (Voigt); and (6) Pavobeisselina oblita (Kade). Some of these species (1, 2, 3, 5) were widespread in the Early Paleocene and the others occurred also in the Late Paleocene.
The second locality (Upper Paleocene) is situated near Nukus, North Uzbekistan. Numerous zoaria are found in the sands exposed inopen pits. Bivalve and brachiopod data determine the age of these sands(Kahanova, Soboleva & Kovaleva 1965). The following Cheilostomatida are most important here: (1) Monoporella invisitata (Sokurov); (2) Puncturiella (Puncturiellina) cava Favorskaya; (3) Floridina atypica Favorskaya; (4) Coscinopleura angusta minor Voigt; (5) Diplobeisselina nobilis (Levinsen);(6)Frurionella squalida (Mokrinskij); and (7)Psilosecos angustidens (Levinsen). The newly described Ochetosella makarovae and O. lata (Favorskaya, Gordon & Voigt 1996) also occur. The presence of some taxa(2, 3, 5, 6) in common with the Upper Paleocene Sullukapinskaya Formation (Mangyshlak) seems to confirm the Late Paleocene age of these deposits.
P. V. Fedorov, A. V. Krusanov & P. V. Fedorov, Geology Department, St Petersburg University, Universitetskaya nab., 7/9, 199034 St Petersburg, Russia
Phosphatic remains of various organisms were obtained by washing the clays interbedded with limestones of the Volkhov Formation from Babino and Putilovo quarries and also the clays from the cores of peculiar organic constructions, so-called Hecker-type "mud-mounds". Among the calcium phosphate remains area large number of ellipsoidal, subspherical, egg-like structures with diameters of 0.05 - 0.3 mm. They are brown or greyish-brown in colour. Similar structures have been described by various authors who have studied fossil bryozoans in thin section where they are sometimes found inside the zooecia. G. G. Astrova (1964,1965, 1971) interpreted them as phosphatized "brown bodies" of bryozoans of the Order Trepostomida. Thin-walled, meandering, labyrinthic pipes with diameters of 0.2 - 0.5 mm are met more rarely. They are constructed of nonstructural, semi-transparent calcium phosphate. Such pipes from Ordovician of Poland and the Ukraine and from glacial erratics are sometimes interpreted as remains of problematic organisms placed in the genus Labyrinthotuba (Gorka 1969; Ginda 1986). However, our findings of meandering phosphatic pipes in small zoaria of trepostomids allows us to identify them as phosphatized fragments of zooecia with hemiphragms. Such an interpretation is confirmed by data from other regions (Conti & Serpagli 1984, 1988). The process of phosphatization of "brown bodies" and zooecial walls took place during life before the biological and diagenetic destruction of the carbonate matter in the skeleton.
This work has been supported by Grant 9-3.1-5 from the National Committee of Science and Higher Education of the Russian Federation.
Ernest H. Gilmour, Department of Geology, Eastern Washington University, Cheney, WA 99004, USA; and I.P. Morozova, Paleontological Institute, Russian Academy of Sciences, 117647 Moscow,Russia
Based on our compilation, there are 101 genera with more than 600 species of Late Permian bryozoans belonging to 28 families and seven orders. Forty-one genera are present in the Roadian, 82 genera in the Ufimian (Wordian ), 84 in the Kazanian (Capitanian), 35 genera in the Dzulfian (Wuchiapingian) and 12 genera in the Dorashamian (Changsingian). The majority of species are usually restricted to a single stage. Most of the genera and families cross the Lower-Upper Permian boundary and survive in the Late Permian seas. Only 20 genera are restricted to a single stage. Late Permian bryozoans differ from those in the Early Permian by the increase in provincialism and by increase in differentiation between Tethyan and Boreal bryozoan assemblages. Late Permian time is characterized by the occurrence of endemic genera from the various families of the order Trepostomida, and by the entry and worldwide distribution of the genera from the family Girtyporidae (suborder Timanodictyina, order Cryptostomida). It was also a time when cosmopolitan genera, such as Dyscritella, Dyscritellina, Pseudobatostomella, Stenopora, Polypora, and Polyporella flourished. The maximum generic diversity of Late Permian bryozoans occurred during the Ufimian and Kazanian, by the end of which more than half of the genera and families had died out. By the beginning of the Dorashamian, the number of bryozoans extant was greatly reduced. During the Dorashamian, only impoverished associations of bryozoans continued to exist in the tropical and subtropical seas. And finally, only four genera survived the Permian/Triassic boundary and existed during the Triassic. Therefore, the decrease in number of Late Permian genera and families beginning with the end of the Kazanian, and continuing to the end of the Dorashamian, was not a sudden phenomenon. Analysis of Late Permian bryozoans has shown that these animals from the Tethyan regions were not as diverse taxonomically in comparison to the boreal associations as was previously believed. One exception would be the northern Tethys where more than 50 genera were present in the Ussurian Province. This may have been a major center for bryozoan diversification during Ufimian time.
V. I. Gontar, Laboratory of Marine Research, Zoological Institute of RAS, University Quay, 1, St Petersburg, 199034, Russia
Many marine invertebrates include bryozoans in their diets. New data about trophic relationships, including the degree of predation, concerns representatives of the family Caprellidae. Metacaprella horrida (G. O. Sars) and Aeginia longicornis (Kroyer) have been found on Eucratea loricata (L.) and Scrupocellaria minor Kluge. Caprella sp.(juv.) has been encountered on Dendrobeania fruticosa (Packard). These caprellids are not obligatory predators and may feed on detritus. If detritus is absent, they may use algae, hydroids and probably bryozoans as food.
V. I. Gontar, Laboratory of Marine Research, Zoological Institute of RAS, University Quay, 1, St Petersburg, 199034, Russia
More than 20 species and subspecies of cyclostomids have been determined from collections made in the region of the Northern and Middle Kuril Islands by the ship "Krylatka" during 1969-1971 on expeditions of the IBS and TINRO. Species were collected from 81 stations, and the 121 samples were made by divers at depths of about 0-40 m. Kluge, Androsova and Gostilovskaia (1959, 1961), Gontar (1978), and Kusakin (1974) previously recorded 11 species and 2 subspecies of cyclostomids in the region of the South Kuril Islands. Kusakin (1974) mentioned one undetermined species for the region of the Middle Kuril Islands (Simushir). In the region investigated for the current study all of the collected species are new for the fauna. The total cyclostomid fauna for the entire Kuril Islands now consists of more than 30 species and subspecies. Five species and 2 subspecies are distributed along the upper shelf of the Kuril Islands. Five species (Stomatopora subrotunda Gontar sp. nov., Tubulipora duplicatocrenata Gontar sp. nov., Crisiella chirpoea Gontar sp. nov., Heteropora urupae Gontar sp. nov.), one genus (Pulvinatopora Gontar gen. nov.) and one family (Pulvinatoporidae Gontar fam. nov.) are new. The biogeographic composition of the cyclostomid fauna in the investigated region includes Boreal-Arctic, Amphiboreal widespread, Asian widespread and High Boreal species and subspecies. The most widely distributed species were Crisia eburnea (L.), recorded at 38 stations, and Disporella buskiana (Canu & Bassler), recorded at 33 stations. The greatest number of species was collected at depths from 15 to 20 metres (12 species and subspecies), and from 20 to 25 metres (16 species and subspecies). Cyclostomids of the upper shelf of the Kuril Islands inhabited hard grounds such as rocks and stones. Many species were found as epibionts of cheilostomids, ctenostomids and hydroids.
R. V. Goryunova, Paleontological Institute, Russian Academy of Sciences, 117647 Moscow, Russia
The autozooid of stenolaemates terminates in two openings, aperture and orifice. These openings are different in structure and frequently in morphology, although they serve the same function - tentacle eversion. In fossil bryozoans, orifices are very rarely preserved, whereas the apertures of the Paleozoic bryozoans are preserved and have been extensively studied. Based on widely known data and the latest discoveries in the morphology of fossil and modern bryozoans, the following conclusions are possible: (1) Paleozoic bryozoans possessed three different types of apertures: rounded, polygonal, and oval. Of these three, the rounded apertures, which were apparently the earliest, were dominant.(2) The evolution of Paleozoic bryozoans shows two trends in aperture morphology: a change from the less accurately rounded apertures(Cystoporida) through the polygonal-rounded (Trepostomida) to the long-oval (Rhabdomesida); and from the rounded(Cystoporida) to the rounded-oval (Cryptostomida) and then to the accurately rounded small apertures (Fenestellida). (3) Aperture morphology is dependent on the shape of autozooecia. (4) Changes in the rounded apertures of Cystoporida were accompanied by the emergence of lunaria and by an increase in the distances between their centres. (5) A trend towards regularly arranged apertures from chaotic (Cystoporida, Trepostomida), to those arranged in strictly regular longitudinal rows and diagonals, emerged at the beginning of the Middle Ordovician. This trend is displayed only by the oval and accurately rounded apertures. (6) Regular arrangement of the apertures is a consequence of the constant position of the locus of budding, which defines the type of colony: spiral (Rhabdomesida), bifoliate (Cryptostomida), and bilateral (Fenestellida). (7) A strictly regular orientation of lophophores and tentacles certainly increased the efficiency and coordination of functions, reduced the disturbances of micro-flows resulting from the movements of millions of cilia, and increased the efficiency of feeding in these sedentary organisms.
R. V. Gorjunova and A. V. Markov, Paleontological Institute, Russian Academy of Sciences, Moscow, 117647, Russia
The research is based on morphofunctional analysis (Gorjunova 1992) and the analysis of quantitative parameters (Markov & Naimark 1995). The early history of bryozoans is characterized by rapid taxonomic and morphological radiation in the Ordovician, beginning in the Arenig. During the Ordovician almost all bryozoan orders and suborders originated, and most morphological characters appeared, occurring only in different combinations in later periods. The attached mode of life and colonial nature strongly limited the possibilities for bryozoan adaptation; nevertheless, bryozoans were able to survive through a number of ecological crises of different scales. The first big reorganization of the bryozoan biota took place in the Silurian. At the Ordovician/Silurian boundary the first wave of the bryozoan evolution, the so-called inadaptive taxa (Ceramoporina, Halloporina, Paleotubuliporina, Cryptostomida, Phylloporinida), which were predominant during the Ordovician, were replaced by the second wave of "euadaptive" groups (Fistuliporina, Hexagonellina, Amplexoporina, Rhabdomesida, Fenestellida), which were comparatively rare during Ordovician. These two groups of bryozoan taxa are characterized by different morphogenetic strategies and, especially, by a different chronology of phylogenetic phases (extensive divergence, acme and decline). Starting in the Silurian, some taxa (Fistuliporina and Hexagonellina) increased their ecological tolerance by simplifying their morphological structure and developing vesicular tissue. In the Amplexoporina ecological tolerance increased because of the development of polymorphism and the loss of diaphragms and cystiphragms. The rhabdomesids demonstrate the most peculiar morphogenetic strategy: the size of all colonial structures decreased, the budding locus became stable, and complicated polymorphism developed; the latter event coincided with the phase of acme of the order. The most rapid extensive divergence during the Silurian took place in the order Fenestellida. This group became predominant because of its unique morphological characters. The large-scale change of the dominant bryozoan groups can be explained with the help of the hypothesis (Markov & Naimark 1994) that internal competition is more severe in dominating groups, and therefore that ecological specialization is more likely here than in the secondary groups.
Andrei V. Grischenko, Department of Hydrobiology and Ichthyology, Faculty of Biology and Soil Sciences, St-Petersburg State University, 16 Liniya 29, St-Petersburg, 199178, Russia; and Alexander V. Martynov, Institute of Marine Biology FEB RAS, Paluchevskogo str. 17, Vladivostok, 690041, Russia
Bryozoa are not common food items for other animals. However, species of several taxonomic groups can eat them: sea spiders (Wyer & King 1973), turbellarians (Kluge 1962), sea urchins (Ryland & Hayward 1977), sea stars, ophiuroids, molluscs (Gordon 1972), fishes and eider ducks (Osburn 1921). Nudibranch molluscs prefer Cnidaria and Spongia, with Bryozoa in third place. Diets of more than 100 species of nudibranchs include bryozoans (McDonald & Nybakken 1991). Among the Doridacea there are two main strategies for feeding on Bryozoa: sucking zooids in encrusting species, and biting off parts of erect branching colonies. Molluscs belonging to the genera Colga and Triopha feed in the second manner exceptionally. The diets of Colga (C. pacifica, Colga n. sp.) and Triopha catalinae, which inhabit different regions of the North Pacific (Alaska Gulf, Commodore Islands, Eastern Kamchatka, Kuril Islands, Sakhalin Island, Moneron Island, North-Western Japan Sea), include only cheilostome and cyclostome Bryozoa. The feeding-spectrum and the proportion of different bryozoan species taken varies in the different regions. Fixed-erect branching and foliaceous bryozoans (Bugula, Caberea, Corynoporella, Crisia, Eucratea, Tricellaria, Scrupocellaria and Dendrobeania) are predominant in the diets of the molluscs in all studied areas. The proportions of erect bryozoans depends on the specific distributions of these bryozoan species. Colga abildgaardi from the Barents Sea was observed by us to have a similar dietary properties. Erect forms of Bryozoa are also prevailed in the diet of Triopha catalinae from Californian coastal waters (McDonald & Nybakken 1978). The depths inhabited by these dorids partly overlap: bryozoans were eaten by Triopha catalinae and Colga n. sp. at depths of 5-69 m, and by Colga pacifica on the outer shelf and in the bathyal at depths of 50-1070 m.
Alexey V. Gryshankov, Department of Invertebrate Zoology,St-Petersburg State University, Russia
Research was carried out in Solovetskiy Bay, a small shallow part of Onega Bay (White Sea) with strong water currents and a prevalence of hard grounds. The macrobenthos includes 407 species of animals, of which 78 are Bryozoa, more than any other group of animals. The substratum distribution of 51 bryozoan species was studied. The commoner substrata (some species of algae, erect hydrozoans and bryozoans, the bivalves Chlamys and Modiolus, stones, and shells of dead molluscs) were analysed. Most of the bryozoans seem to be relatively stenotopic, i.e. they are recorded on particular types of substrata with significantly greater frequency and/or abundance. This allows the investigated species to be divided into five groups associated with: (1) algae; (2) erect hydrozoans and bryozoans; (3) any flexible substratum; (4) any hard substratum; and (5) species showing no preferences. The latter group contains the smallest number of species. The patterns of distribution are likely to result from differences in abiotic conditions at the sites of sampling as well as features of the substrata themselves. Substratum features are more significant for the majority of the studied bryozoan species, as shown by multifactor Analysis of Variance. The role of Bryozoa on various substrata is different. On flexible substrata species of bryozoans prevail numerically and in their area of attachment. Dominance usually does not occur. Competition is probably not important, although cases of overgrowth of colonies by one another are quite frequent. Communities on stones and shells are strongly dominated by barnacles, which monopolise a lot of space, while Bryozoa play a secondary role. Bryozoan abundance is determined not only by properties of the substrata but also by some abiotic factors such as depth, silting and local hydrodynamic regime.
Steven J. Hageman, Department of Geology, Field Museum of Natural History, Roosevelt Road at Lakeshore Drive, Chicago, Illinois 60105, USA; and Micha M. Bayer and Christopher D. Todd, Gatty Marine Laboratory, School of Biological and Medical Sciences, University of St. Andrews, St. Andrews, Fife KY16 8LB, Scotland, U.K.
The significance of species based on hard part morphology alone has been along-standing question in biology and paleontology. How much morphologic variation in a population is due to genetic control and how much is a response to environmental conditions? Using colonial organism such as Bryozoa, morphologic variation can be partitioned into: within colony (same genome) and among colony components. We have performed experiments using live bryozoans grown under controlled environmental conditions, with known genetic and environmental factors. Three colonies (genomes) of Electra pilosa were cloned, with one segment of each of the three genomes grown in one aquarium, and the other three in a second aquarium under identical environmental conditions. Six morphometric skeletal characters were used in cluster analysis, principal component analysis and in a series of analysis of variance tests in order to compare the morphology of individual zooids within and among genomes, and treatments (different but nearly identical environments). Numerical analyses demonstrate a strong genetic control over zooid morphology and minor treatment effects. Treatment (ecophenotypic) effects are manifested differentially depending on the genome (genome* treatment interaction). Ecophenotypic effects can change morphological characteristics within the same genome (parent vs daughters grown in different treatments) in the following ways: (1) group means can differ; (2) group variance can increase or decrease; or (3) change can be coordinated (uniform directional change of all members) or independent (mixed response depending on genome).
Numerous other morphometric studies by other workers on modern and fossil bryozoan species (anascan cheilostomes, ascophoran cheilostomes, Paleozoic fenestrates and rhabdomesids), demonstrate that individual zooids can be assigned to the colony segments (genome) from which they were measured. In addition, the morphology of separate species are generally discrete. Therefore, well documented morphologic taxa have biological significance and analysis of subspecific morphologic variation is possible in fossil bryozoan taxa.
Konstantin V. Khalturin, Department of Invertebrate Zoology, St Petersburg State University, St Petersburg, Russia
The encrusting bryozoan Electra pilosa forms extremely dense settlements on the fronds of Laminaria saccharina and L. digitata at Kandalaksha Bay in the White Sea. Colonies of this species are star-shaped with many beam-like rows of zooids. Distribution of the colonies along the blades, measurement and estimation of colony form asymmetry and analysis of astogenetic models of Electra pilosa were the main aims of investigations carried out during 1995-96 at the Marine Biological Station of St Petersburg State University (Middle Island). Computer programs were specially designed for the purpose of this research. It was found that the ancestrulae of E. pilosa are orientated mainly parallel to the longitudinal axis of the fronds. In addition a directed growth pattern is typical for E. pilosa - colonies tend to bud new zooids "distally" (towards the end of the frond) with a higher frequency than in other directions. Hence, the form of the colony is usually asymmetrical. The main growth direction of the colony depends neither on its location on the frond, nor on the orientation (direction) of the ancestrula. According to preliminary results, the mechanism causing directed growth in E. pilosa is a modification of the astogenetic model depending on the gradients of environmental factors which are present along the frond of the seaweed. The computer analysis of mapped colonies revealed a few types of stable dependence between the early astogenetic model (budding processes in the first 5-7 generations) and the orientation of the ancestrula relative to the longitudinal axis of the frond. This supports the inference that E. pilosa has the ability to regulate and choose its direction of growth.
V.Kvatchko, St.-Petersburg State University, 7/9 Universitetskaya nab., 199034 St.-Petersburg, Russia
The genus Volviflustrellaria was introduced by Brydone in 1936 for Membranipora taverensis from the Upper Campanian of England, whose colonies, in his opinion, were rather meagre, both in the number of individuals and in their size. Brydone included Volviflustrellaria in the group of Membraniporidae, distinguishing the very exceptional zoarial structure. Whereas Voigt (1975) included V. taverensis in the Lunulitidae, Cook and Chimonides (1986) excluded Volviflustrellaria from this family but included it in a group of cheilostome genera with flabellate zoaria - Reptolunulites d'Orbigny, 1852 and Pavolunulites d'Orbigny, 1852. Unfortunately, Cook and Chimonides did not indicate the family in which these genera should be placed.
Volviflustrellaria has globular or spindle-shaped colonies. At the earliest stages of their growth, like zoaria of lunulitiform bryozoans such as Lunulites or Cupuladria, colonies apparently encrust a small substratum. This may comprise a small grain of sand or a foraminiferan, although Cook and Chimonides supposed that the substratum may have been an alga or a hydroid. Subsequently, colonies rapidly overgrow the substratum and continued to grow using the earlier generations of their own zooids as a substratum. As a result, colonies have a distinctive globular or spindle-shape, the exact shape possibly depending on the length of the growing edge of the colony. These zoaria may possibly have rested motionless on the sea bottom, stabilized by their vibracula, or have rolled. The second option is considered more likely because in colonies with a globular or spindle shape it would be very difficult to maintain a stable position on the sea bottom supported by the vibracular setae, in contrast with lunulitiform bryozoans which have more stable discoidal or domed zoaria. On the basis of the morphology of the colonies and their relationship with the substratum, Volviflustrellaria cannot be included in the lunulitiform bryozoans.
Vera Kvachko, St.-Petersburg State University, 7/9 Universitetskaya nab., 199034 St.-Petersburg, Russia; and Eckart Håkansson, Geological Institute, Öster Voldgade 10, DK-1350, Copenhagen K, Denmark.
Free-living bryozoans are conspicuous members of many cheilostome faunas from Late Cretaceous to the present. Following a prominent diversity high comprising several free-living clades in the latest Cretaceous, Maastrichtian chalk sea of northern and eastern Europe, this highly specialized group of bryozoans experienced a severe crisis at the Cretaceous -Tertiary boundary, when the prolonged stability of the chalk sea environment was disrupted. As a result, most free-living clades had vanished by the earliest Paleogene (Danian). During the Paleogene a number of new free-living clades evolved, and thus far only taxa with strong ties to the Lunulites clade have been recorded to survive the boundary. In Danian sediments such probable survivors are restricted to the very same region where the clade flourished in the Maastrichtian, whereas free-living cheilostomes of other clades are present in Danian sediments on several continents.
The most central taxon in the Paleogene recovery of the Lunulites clade appears to be Lunulites saltholmensis Berthelsen, 1962, which is presently known from the Danian of Denmark, Crimea (Ukraine),and Mangyshlak (Kazakhstan). While this species is very rare in Denmark, it occurs abundantly in both Crimea and Mangyshlak, where it is also associated with other, mainly closely related species of Lunulites. In this presentation we reconsider the taxonomy of the Danian Lunulites, and discuss the relations between the Danian and Maastrichtian members of the Lunulites clade.
V. D. Lavrentjeva. Paleontological Institute, Russian Academy of Sciences, 117647 Moscow, Russia
Transcaucasia is one of a few world areas where continuous marine sediments from the Emsian to the Visean are exposed, which are characterized by abundant bryozoans represented by five orders, 12 families, 49 genera and 105 species. The oldest Emsian/Eifelian assemblage consists of 17 species belonging to 16 genera, which are characteristic also of coeval deposits in Altai, Kazakhstan, Kuzbas, Mongolia and China. Discovery of the genus Utropora, an endemic for the Pragian (Lower Devonian) of the Czech Republic and France, is interesting. Eifelian bryozoans are represented by three associations confined to three brachiopod zones. They are scarce in the lower zone, but their taxonomic diversity gradually increases and attains its maximum in the upper part of the Eifelian, owing mainly to the increase in number of cosmopolitan genera. 36 genera and 50 species of Eifelian bryozoans include some new species, a new rhabdomesid genus and a new Fenestrapora species characterized by avicularia, and believed to be an endemic of the American Devonian. Taxonomic composition of Late Eifelian bryozoans shows that the latter lived in most favourable conditions, and that marine basins were widely connected at that time (Transcaucasia and several regions of Asia, Europe, America). Givetian bryozoans are represented by two strongly impoverished associations corresponding to two brachiopod zones. They include 12 genera, 10 of which are common with the Eifelian, and 16 species (one new), the other known from the Givetian of Kuzbas and Gorny Altai. Two Frasnian assemblages are recognized, corresponding to two brachiopod zones. Six genera survived from the Givetian. In total, 16 genera and about 30 species (several new) are identified, which are known from the Frasnian of Asia, Poland, Kanada. Four brachiopod zones are recognized in the Famennian, only three of them being characterized by bryozoans. The latter include 22 species in 17 genera, four of which survived from the Frasnian. Several species are new, the majority of the others being known from the Famennian elsewhere. In the Early Tournaisian the taxonomic composition of bryozoans is totally renewed (except for two genera).
D. V. Lysitsyn, Paleontological Institute, Russian Academy of Sciences, 117647 Moscow, Russia
Hederellids are a poorly studied group established by R. S. Bassler (1939) as a suborder of uncertain affinities within the phylum Bryozoa. Representatives are known from the Silurian, Devonian and Carboniferous of North America, Eurasia and Australia. Only two species belonging to the most widespread genus Hederella have been described in Carboniferous rocks: H. chesteriensis Bassler and H. carbonaria Condra and Elias (Bassler 1939; Condra and Elias 1944; Bancroft 1986). In 1989 I found five colony fragments of the genus Hederella in the Lower Permian (Sakmarian) reefal massif on the right bank of the Ayi River (Ufa River basin, northern Bashkiria). They were recovered from the lower part of the reef. The associated fauna consists of abundant bryozoans of the orders Cystoporida, Trepostomida, Rhabdomesida and Fenestrida described by V. B.Trizna (1950), and brachiopods, bivalves and ammonoids. The colonies of Hederella consist of several dichotomizing branches expanding across the substratum in different directions. They attain a size of 50 mm or a little more. The branches are composed of elongated, gently sinuous cylindrical stolozooecia. Gently sinuous, cylindrical autozooecia are budded from the stolozooecia, alternating on either side of them, at angles of 20-50° and closely spaced intervals (up to 2 mm ). Their proximal parts are in contact with stolozooecia or with neighbouring autozooecia for some distance, rarely along all their entire length, or alternatively they are free. In longitudinal section, zooecial walls have a wavy profile, especially from the external side, a fact which seems to indicate the presence of transverse ridges. Zooecial apertures are not preserved. Rarely, thin and slightly concave diaphragms can be observed. The specimens studied belong to the species Hederella carbonaria Condra and Elias, 1944, widespread in the Upper Carboniferous (Lower and Middle Pennsylvanian) of North America (Condra and Elias 1944) and is also found in Lower Carboniferous deposits of Great Britain (Bancroft 1986). Uralian specimens are closely similar in their wall thickness, zooecial length and diameter to North American and British forms. This is the first finding of H. carbonaria outside North America and Great Britain, and extends the stratigraphic range of this species (and consequently that of the genus and the suborder) to the Lower Permian.
O. P. Mesentseva, Department of Physical Geography, Pedagogical Institute, Pionersk Prospekt, 7, Novokuznetsk, 654027,Russia
The dynamics of the development of the Trepostomida in the Altai-Sayan region during the Devonian period has not been considered previously because of poor knowledge of Emsian and Eifelian complexes. Research on the Emsian deposits of Salair and Gorny Altai has resulted in the discovery of 47 species and 4 subspecies, 35 of which turn out to be new. A comparison of the Emsian complex of Trepostomida and Late Givetian trepostomids shows that they have no species in common. It is conjectured that during Eifelian/Early Givetian time Trepostomida of the Altai-Sayan region experienced a major renewal of species like that also apparent at the Pragian/Emsian boundary. The study of collections made from strata along the continuous section of the Emsian in the Gurievsk area revealed two biostratigraphic boundaries characterised by large changes in the specific composition of the Trepostomida. The first boundary, coinciding with the Limit of the Middle and Upper Salairka subhorizons (probably part of the gronbergi Zone), is characterized by the disappearance of 10 species and the appearance of 4 new species. The second boundary, corresponding to the limit of the Middle and Upper Shanda subhorizons (lower part of the partitus Zone), shows the disappearance of two and appearance of 10 species and subspecies. These changes are probably not bound up with facies changes because coeval Emsian deposits in Salair with different facies do not differ significantly in species composition. The presence of phases of intensive change in species composition reflects the staged character of the development of Trepostomida during Early/Middle Devonian time. These findings contribute to our knowledge of trepostomid development on a global scale.
O. P. Mesentseva, Department of Physical Geography, Pedagogical Institute, Pionersk Prospekt, 7, Novokuznetsk, 654027, Russia; and M. F. Gabova and V. R. Savitsky, Paleontological Laboratory, West-Siberia Experimental Centre, Novokuznetsk, 654011, Russia
Study of the intraspecific variability of Palaeozoic Bryozoa, a necessary element of population analysis, is considerably simplified if, instead of repeated survey of ground ends under a microscope, their magnified imprints are analysed. Mass photography of ground ends is very expensive. We studied the magnified imprints of liquid-covered ground ends using a computer system comprising a "Uniscan" projector scanner , a 386 DX-40 computer and an "Optra R" printer with 1200 dpi output. Five to 10 x magnification was provided by the scanner. For 10 to 50 x magnifications an MBI-3 microscope with a skimocular part and object glasses 8 and 10 was used. Computer editing of the captured images was made using the program Photo Styler. With the memory of the printer 2 Mb, the area of the hardcopy output is limited to 28-30 square cm. With an increase of printer memory to 4 Mb the maximum area of the output increases to 300 square cm. A printer memory of 8 Mb allows output on A4. In clarity and content the output does not match conventional photographs but it is possible to adjust levels brightness caused by differences in original ground ends.
I.P. Morozova, Paleontological Institute, Russian Academy of Sciences, 117647 Moscow, Russia
M. K. Elias and G. E. Condra (1957), the authors of the order Fenestrida, thought that the 'colonial plexus' distinguished by them in the wall structure of these bryozoans was homologous with the 'common bud', or 'colonial bud', in Cyclostomida, and on this basis referred the new order to the class Stenolaemata. Though these authors, like many others (Ulrich 1890; Cumings 1904; Levinsen 1925; Marcus 1925; Shulga-Nesterenko 1949) noticed a great similarity between fenestelloid and cheilostomatous bryozoans, and assumed Fenestrata to be ancestral to Cheilostomata, modern authors traditionally include Fenestrida in the class Stenolaemata. However, a comparative analysis of morphological characters of Fenestrida and those of the bryozoans of the classes Stenolaemata and Eurystomata shows that the Fenestrida should be assigned to Eurystomata. The main characters distinguishing Fenestrida from Stenolaemata are as follows:(1) type of ancestrula and the pattern of arrangement of the first generation buds which are close to those of Eurystomata; (2) structure of autozooidal chambers; (3) external type of budding; (4) differentiation of walls in autozooids, particularly expressed in strong thickening of the basal parts of the chambers; (5) presence of ovicells morphologically close to those of cheilostomatous bryozoans; (6) presence of avicularian chambers in the colonies of some genera, the morphology of which and their arrangement are similar to avicularian chambers of ascophoran bryozoans (Morozova and Lavrentjeva, in press); and (7) peculiar colonial architecture with wide variations of their vital forms, more complex than in Stenolaemata. Therefore, the many features shared by bryozoans of the Paleozoic order Fenestrida and Mesozoic Eurystomata separated by a large time interval cannot be explained by the phenomena of homeomorphy or heterochronous parallelisms. The main obstacles to an unconditional inclusion of Fenestrida in Eurystomata are the absence of transitional forms and phylogenetic discontinuity between these two bryozoan groups. One can only assume that the reason for this might be connected with the large gaps in the paleontological record due to the global events at the boundary of the Paleozoic and Mesozoic eras.
Hans Arne Nakrem, Paleontological Muséum, University of Oslo, Sars' gt. 1, N-0562 Oslo, Norway
During the "IKU Petroleum Research Shallow Drilling Programme" in the Norwegian part of the Barents Sea, close to 50 shallow cores have been drilled. Carboniferous and Permian strata have been penetrated at the Svalis Dome (Nilsson et al. 1996, Norsk Geologisk Tidsskrift 76 (3), 127-146) and the East Finnmark Platform from where fusulinids and palynomorphs have been published recently (Bugge et al. 1995, Norsk Geologisk Tidsskrift 75 (1), 3-30). These rocks contain abundant bryozoan faunas which have been compared to, and correlated with contemporaneous faunas from adjacent areas, mainly Svalbard, northern Greenland, Timan-Pechora and Novaya Zemlya.
Drilling site 7129/10-u-1 penetrated Triassic through Artinskian rocks (palynomorph and fusulinid dating). The "middle" and late Permian succession contains the richest bryozoan faunas, with species in common with the Tempelfjorden Group of Svalbard. Taxa include Cyclotrypa distincta Morozova, C. eximia Morozova, Ramipora hochstetteri Toula, several trepostomes (Tabulipora, Rhombotrypella and Dyscritella), Primorella polita Romanchuk & Kiselëva, Clausotrypa monticola (Eichwald), Timanodictya nikiforovae Morozova and abundant fenestrates. The uppermost part contains bryozoans unknown from Svalbard, e.g. Hinganella improvisa Morozova, a species of Neoeridotrypella (of possible Kazanian affinity as compared with Novaya Zemlya) and other undetermined trepostomes. The Artinskian succession contains taxa occurring in the Gipsdalen Group of Svalbard, e.g. indeterminate species of Goniocladia, Penniretepora, Rhabdomeson and Archimedes. More age diagnostic species (e.g. Coscinium cyclops Keyserling, Ascoporaster litamakensis Nikiforova, Ascoporella cf. grandis Morozova and Timanodictya dichotoma (Stuckenberg)) provide a better biostratigraphic correlation with the Tyrrellfjellet Member of the Nordenskiöldbreen Formation at Spitsbergen.
Drilling site 7129/10-u-2 penetrated rocks of latest Gzhelian through earliest Artinskian age (fusulinid dating). The bryozoan fauna in this core is easily correlated with the lower part of core 7129/10-u-1, having species in common with the Tyrrellfjellet Member of the Nordenskiöldbreen Formation at Spitsbergen (see above), and the Hambergfjellet Formation of Bjørnøya, e.g. Timanodictya dichotoma (Stuckenberg).
Although many bryozoans in the investigated cores have a wide stratigraphic distribution, it was possible to perform a local correlation between these cores as well.
L. V. Nekhorosheva, Department of Stratigraphy of VNII Okeanologia, St Petersburg, 199034, Russia
Bryozoans from Palaeozoic deposits of the Severnaya Zemlya archipelago were collected for the first time in the 1970's during geological surveys and special studies. Ordovician bryozoans were found in sections of the Ozerninskaya Formation of the Middle Ordovician on Oktyabrskaya Revolyutsia Island. Devonian bryozoans, represented only by fistuliporids, were found in the Rusanovskaya Formation on Pioner Island and bear some similarity to bryozoans of the Lower Devonian of Central Taimyr. Permian bryozoans were found on Komsomomolets Island, in the lower part of the Zhuravlevskaya layer which palynological evidence correlates with the Kungurian Stage. Bryozoans of the Zhuravlevskaya layer are represented by dyscritellids.
E. Nikulina, Biological Faculty of Moscow State University, Moscow, 119899, Russia
In the study of polymorphism there is a problem of non-accordance in the selection of polymorph attributes. Some authors consider particulars of skeletal morphology as the main criterion (convenient for palaeontologists), whereas others apply a functional separation. The term sexual polymorphism is often used. Such uncertainty can be avoided by separating three aspects of polymorphism: morphologic, functional and sexual. In many papers astogenetic changes, as well as the spatial arrangement of polymorphs, are neglected.
The spatial-polymorphic structure of the encrusting cheilostome bryozoan Cribrilina annulata (Fabricius, 1870) was studied using an original method based on independent examination of morphological, functional and sexual colony structure and patterns of development. I. Morphologic structure is represented by three types of zooids: 1, zooids of early generations; 2, ovicellate zooids; 3, adventitious dwarf zooids. II. Sexual structure is represented by four types of zooids: 1, infertile zooids (ancestrula and partly I.1); 2, male zooids (majority of I.1); 3, bisexual zooids (I.2); 4, female zooids (I.3). III. Functional structure is represented by three groups of zooids, united by execution of the same function: 1, feeding zooids (ancestrula, II.1); 2, zooids combining feeding and reproduction (II.2, II.3); 3, zooids specialized for reproduction (non-feeding) (II.4). Each of these structural groups has its own strategy of development which are not correlated with the others. As a result we observe a complex situation with differences in polymorph number and disagreements in polymorph interpretation.
Andrew N. Ostrovsky, Department of Invertebrate Zoology, Faculty of Biology & Soil Science, St. Petersburg State University, Universitetskaja nab. 7/9, St. Petersburg, 199034, Russia
During a study of idmidroniform bryozoans collected in different parts of the Antarctic in the course of the 34th and 36th Soviet (Russian) Antarctic Expeditions, many variations of ooeciostome morphology and position were encountered. More than 550 fertile colonies and fragments with ooeciostomes belonging to seven species (Exidmonea arcuata Ostrovsky and Taylor, Idmidronea hula Borg, I. antarctica Borg, I. pseudocrisina Borg, I. obtecta Borg, I. pellucida Ostrovsky and Taylor, and I. fraudulenta Ostrovsky and Taylor) were studied. All characters examined (size and shape of ooeciostome and ooeciopore, ooeciostome position, orientation of ooeciopore) exhibit variability. Although every species is characterized by a distinct shape and position of the ooeciostome that allows its use (together with other features) as dependable characters in taxonomy, deviations from the "normal" morphology of the ooeciostome are too common and considerable to be ignored. Therefore, ooeciostome characters may be characterized as useful rather than diagnostic taxonomic characters.
Recent idmidroniform bryozoans can be arranged in a morphoseries reflecting possible stages in the evolution of the ooeciostome. Possible trends include loss of terminal position, length decrease, increased curvature and flattening. A reason supposed for these modifications might be connected with the "passive defence" of the ooeciostome from breakage and destruction.
Vladimir P. Ozhgibesov, Perm State University, Bukireva str., 15, Perm, 614600, Russia
In a joint article with R. J. Cuffey, the author of the present abstract introduced the term 'The Main Permian Basin' (Ozhgibesov & Cuffey 1996). The term is derived by analogy with the concepts of the 'Permian Basin' of North America and 'The Main Permian Field' (Gorskiy 1988) of the globe.
The character of faunal change in various Permian Basins of sedimentation differs, a fact which follows from the presence of endemic taxa. The estimated rate of generic evolution in the Main Permian Basin (MPB)is of special interest as it is here that the Permian System was first established. Identification of standard geological sections for the Permian in marine deposits is a logical way of devising a common time-scale. In contrast, allocation of three different stratotypes for divisions of the Permian System in three different basins is a not a good procedure. Divisions of the system should be linked with major events which are reflected in biological groups of ecological (and palaeoecological) significance, including bryozoans. Bryozoans overcame palaeogeographical barriers inaccessible for more stenohaline groups. Rates of change of bryozoan generic diversity in the MPB have been investigated. For this purpose I have used K-Ar dating for Permian geochronological intervals of the standard MPB stages (a; s; ar; k/u; k; t), and data on the numbers of genera present in the MPB. I have calculated the following rates of change in generic diversity (number of genera per one million years). Rates of generic addition: 1.5; 1.0; 0.7; 0.2-0.3.2; 3.2; (2). Rates of generic elimination: 0.3; 0.2; 4.4; 0.1/3.2; 12.1; (1) (Ozhgibesov 1995, 1997). 'Coefficients of relative increase of rates' reveal the existence of two crises (Artinskian and Kazanian) in Permian bryozoan communities from the MPB: 5; 5; 0.2; 2/1; 0.3; (2). Coefficient of 'relative' increase of rate is dimensionless.
E. M. Partaly, Flat 59, Stroitelei Prospekt 62, 314025, Mariupol', Ukraine
Three species of Bryozoa exist in the fouling communities of the Asov sea: Bowerbankia imbricata, Victorella pavida and Conopeum seurati. Settlement of larvae occurs from May to September at temperatures of 12-25°C for the two ctenostomatid species, and 18-26°C for C. seurati. On artificial substrata, the number of zooids which formed during 10 days was 70 in B. imbricata, 460 in V. pavida, and 390 in C. seurati. After a month of development 14,000 zooids fill an area 10 x 10 cm in size. Larvae prefer substrata with a slimy surface. When settlement of balanoids and mytilids was lacking, bryozoans formed the first layer of the fouling community with, during the summer months, ctenostomatid species occupying 2-51% of the area of the artificial substrata, and C. seurati 3-21%. Ctenostomatid species occupied 2-30% of the area of artificial substrata between 2 and 6 months, and C. seurati 3-10%. Bryozoans were found to settle on other fouling species such as balanoids and mytilids when more prolonged observations were made. Bryozoa developing on shells of Balanus improvisus may occupy the following vertical layers in the fouling community: layers I-II during the first month and between months 2 and 6; layers I-III after 8 months; layers III-VIII after 12 months; and layers I-VIII after 3-5 years. Bryozoan larvae may settle on stolons of the hydroid Bougainvillia megas and occupy layers I-IV in the vertical structure. These bryozoans lead to a reduction in the stolons. Bryozoa found on shells of Mytilus galloprovincialis occupy layers I-III of the fouling community. On Balanus shells the estimated density of bryozoan zooids after one month reached 34-118 per square cm for the ctenostomatid species, and 269 per square cm for C. seurati. The number of zooids estimated to be present in one square cm of hydroid stolon reached 3-5, equivalent to 7200 -9900 zooids of the ctenostomatid species per gm of hydroid colony, and 5100 zooids of C. seurati per gm of hydroid colony. The weight of hydroid colonies encrusted by C. seurati reached 160 to 2300 gms on the 10 cm x 10 cm artificial substrata. Seven zooids of B. imbricata occurred on Mytilus shells 6 mm in size, and 300 zooids of C. seurati on Mytilus shells 7 mm in size.
A. G. Plamenskaya, Apt #10, str. Shevchenko 115, 480059, Almaty, Kazakhstan
Bryozoa are distributed unevenly in the Carboniferous of Kazakhstan. They are most numerous and heterogeneous in the Lower Visean of central and south Kazakhstan. Bryozoa are less abundant in the Upper Visean and Serpuchov stage of these regions and in east Kazakhstan. Middle Carboniferous Bryozoa have an insignificant spread in the Jungaro-Balchash Region. Among many cosmopolitan species and genera there are some uncommon bryozoan taxa. One group of genera are seldom found in the Carboniferous of Kazakhstan but are well-known in the other regions of the world. A second group of genera, well-known in Upper Paleozoic sediments elsewhere, are recorded for the first time in the Lower Carboniferous of Kazakhstan. The third group comprises endemic genera. Most of these uncommon genera have not been described previously from Kazakhstan, and therefore the facts below may be of interest with regard to stratigraphical and geographic distributions, mechanisms of migration and possibly identifying the centres of first appearance of some bryozoan genera. Genera in the first group comprise Syringoclemis Girty, originally described from the Upper Mississipian of North America (Clt 2 Betpakdala, south Kazakhstan), and Minoclema Sakagami, originally described from the Middle Visean Akioshi Limestone Group of Japan (C 2tl m. Karatau). In C1V1 of Kazakhstan are found Cheilotrypa Ulrich (S-P), Anisotrypa Ulrich and Callocladia Girty, genera originally described from the upper Mississippian of North America. In CIS of southern Kazakhstan occur Parastenodiscus Kiseleva (Cl-P of other regions) and Fistuliramus Astrova (S-P of other countries). In the second group are recorded: in Clt2, Fistulicladia Bassler, a genus from Indonesia; in C1V1 of south Kazakhstan and C1V3 of east Kazakhstan, Chianodictyon Foerste known in C2 of the Russian platform and in the Upper Palaeozoic of North America; in C1V2 of Middle Asia and south Kazakhstan, Matheropora Bassler from the Upper Palaeozoic of North America. The third group of endemic genera consists of: Eulyra Plamenskaya (C1V1 of Kazakhstan), Admiratella Plamenskaja (C1V1 of Middle Asia and Kazakhstan), Betpacdanella gen. nov. (CIS of south Kazakhstan), and Kararchimedes Plamenskaja (C1V3 of east Kazakhstan).
Liudmila I. Popeko, Institute of Tectonic and Geophysics,65, Kim Yu Chen Street, 680063 Khabarovsk, Russia
Continuous Devonian and Carboniferous sequences occur in the Aginsky zone of the Mongol-Okhotsk fold system, in the Argun Massif (Transbaikal area) and, most probably, in Upper Priamure. They are characterized by shelf carbonate-terrigenous deposits. The section in the area between the Kotikha and Bystraya rivers in the Argun Massif contains the most abundant and well-preserved bryozoans. In the Aginsky zone (Onon River), bryozoans from the transitional strata are rare and not well-preserved. In both areas, in the Upper Devonian they are accompanied by brachiopods that typify the Sphenospira julii Zone (including the index species), corresponding to the Etroeungt Beds of France and Belgium. The existence of transitional deposits in Upper Priamurie can be suggested from the presence of Nikiforovella bytchokensis Trizna and Laxifenestella juxtaserratula (Trizna), characteristic of the Kuzbasabyshev Horizon, and also the Early Tournaisian Fenestella kassini Nekheroshev. Trepostomida are dominant in the Etroeungt bryozoan assemblage, with Rhabdomesida as subdominants, Cryptostomida present and Fenestellida unimportant. Some trepostome genera range into the Lower Tournasian, where their species diversity increases. The generic composition of the Rhabdomesida remains stable with new species appearing. Fenestellida become dominant and diverse. Reteporina and Semicoscinium are especially abundant, and Minilya, Arborocladia and Reteporidra, which are unknown in the Etroegngt Beds, appear. The upper part of the Lower Tournaisian is characterized by the appearance of Septopora, Polyporella, Polypora and Alternifenestella. The Devonian-Carboniferous transitional deposits from Transbaikalia contain a large number of species identical or similar to bryozoans from the Brachiopod and Reteporina series of the Tarkhansky Suite in Rudny Altai. The general changes in systematic composition are similar too.
Alexander A.Protasov, Institute of Hydrobiology, 254210 Kiev, Ukraine
The Konin Lakes situated in Wielkopolskie Lakeland consist of several basins - Goslawskie, Patnowskie, Lichenskie and Wasosko-Mikorzynskie - connected by canals. They belong to the Oder-Warta river system. The "Konin" power plant takes water from Lake Patnowskie and discharges heated effluents via canals directly or through an initial cooling reservoir to Lakes Lichenskie, Patnowskie and Wasosko-Mikorzynskie. The temperature in discharge canals reaches 34 °C. In the discharge canal of the Konin power plant the most abundant invertebrate species on solid substrates was Plumatella emarginata . Biomass reached 938.8 g/m³ at a depth 1m, and was more then 1 kg/m³ (1152.0 g) at 2 m deep. In periphytic communities dominated by bryozoans, Nematoda, Ostracoda and Oligochaeta reached high numbers. Colonies of P. emarginata were found in discharge canal on unusual substrates: sandy bottoms. Bryozoan communities were stable summer components of discharge canal ecosystems, but were found also in intake canals where the temperature was 29.5 °C. Here two species of Bryozoa - Plumatella fungosa and P. emarginata - commonly formed communities, making up 33% and 43% of total community biomass respectively. Therefore, the maximum development of bryozoans was reached in the lotic, high temperature conditions of discharge canals. Bryozoans were almost absent in lakes.
There is little information about the spreading of the North American freshwater kamptozoan Urnatella gracilis in European waters. After a first finding in Belgium, this species was reported in the rivers Danube, Dnieper, Dniester and Don. The first finding of U. gracilis in Poland was from the Konin Lakes in the summer of 1993, during our investigations of periphytic communities in discharge canals. In the summer of 1994, the number of two-stolon colonies reached 90,000 per m³, and biomass was 37.2 g/m³. The height of colonies with 2-9 calices was 2.5-3.0 mm. Young spreading (creeping propagation) colonies on substrates were very numerous. According to our observations, P. emarginata and U. gracilis may live together. In this connection it will be very important to investigate biocenotic interrelations between these species and their functional roles in thermophilic periphytic communities.
V. Pushkin, Belorussian Geological Prospecting Research Institute, Staroborisovsky tract, 14, Minsk, 220114, Republic of Belarus.
Early and Middle Ordovician (Arenig-Llandeilo) bryozoans of the Leningrad region (Ingria) were studied from the localities of Volkhov, Lynna, Lava, Popovka, Lopukhinka River, Putilovo, and Babino quarries, and also from some boreholes. The earliest (Early Arenig) bryozoans were found in the upper part of the Latorp Horizon (Billingenian) where a Revalotrypa-Phragmopora Community is recognized (Volkhov, Lava, Putilovo; Popovka-Pushkin and Popov, in press). Small (2-10 mm), nodular (rarely hemispherical) trepostomid colonies belonging to 6 species are present: Revalotrypa eugeniae Gorjunova, R.? arborea (Modzalevskaya), Phragmopora sp. nov., Esthoniopora? lessnikowae (Modzalevskaya), Dianulites helenae(Modzalevskaya), and Hemiphragma sp. nov. In the overlying Volkov (Upper Arenig) and Kunda Horizons (Early Llanvirn), larger (10-30 mm), hemispherical (rarely nodular) trepostomid colonies predominate. These form the Dianulites Community (Pushkin 1987) in which Dianulites helenae (Modzalevskaya), D. multimesoporicus Modzalevskaya, Revalotrypa gibbosa (Bassler) and Dybowskites annulatus (Eichwald) are dominant. Whereas in Latorp time bryozoans populated a narrow (5-15 km wide) part of the basin, extending along the Baltic-Ladoga Glint only in the Leningrad region, in Volkhov and Kunda times this zone widened considerably (40-50 km), and bryozoans populated many shallow basin parts such as in the North Prebaltic (Leningrad region, Estonia) and in the South Prebaltic (Belarus, Lithuania).
The Dianulites Community (mainly hemispherical trepostomids) continued to exist in Azeri and Lasnamyagi times but the systematic composition of this community changed considerably, with Dianulites janischewski Modzalevskaya, D. fastigiatus (Eichwald), D. petropolitanus (Pander), D. apiculatus (Eichwald), Mesotrypa excentrica Modzalevskaya, and Orbipora distincta (Eichwald) predominant. The Llandeilo (Uhaku and Kukruse Horizons) is marked by rapid progressive development of shallow benthos in the Baltic basin, and the area inhabited by bryozoans was considerably widened to about 60-80 km. In most shallow parts of this zone the Mesotrypa Community was developed, containing Mesotrypa excentrica Modzalevskaya, M. pyriformis (Eichwald), Diplotrypa petropolitana (Nicholson), D. bicornis (Eichwald), Esthoniopora communis Bassler, and Dianulites apiculatus (Eichwald). This community changed with increasing basin depth to the Nematotrypa Community in which thin ramose colonies of Nematotrypa gracilis Bassler (Rhabdomesonida), ramose colonies of Batostoma, Hallopora, Hemiphragma and Dybowskites (Trepostomida), and bifoliate colonies of Graptodictya and Pachydictya (Cryptostomida) dominated.
N. P. Schastlivtseva, Paleontological Institute, RAS, 117647 Moscow, Russia
K. F. Mather (1915) established the new Carboniferous genus Dictyocladia from the Morrow Formation of the USA with the following diagnosis: "Zoaria poriferous on the one side only, pinnate or loosely fenestrated expansions consisting of primary branches with numerous lateral branches; lateral branches united at intervals by the union of non-poriferous pinnae from adjacent branches. Zooecia in three or more rows along primary and internal branches; reverse or non-poriferous side with scattered dimorphic pores." Later R. S. Bassler (1953) discovered that the name Dictyocladia was pre-occupied and replaced it with Matheropora. Without any investigation of the internal structure of the colonies, following Mather, he included this genus in the family Acanthocladiidae and published the following short revised diagnosis: "like Acanthocladia, but main stems have 4 or 5 rows of zooecia and side branches partly joined by dissepiments." Investigations of replicas of tangential and transverse sections of the holotype colony of the type species of this genus sent to the bryozoan laboratory of PIN by Professor F. K. McKinney (Department of Geology, Appalachian State University) have allowed the recognition of important new characters of the genus Matheropora. The new characters include the structure of the zooecial chambers, presence and arrangement of cyclozooecia on both sides of the colony, and absence of ridges and nodes dividing the rows of zooecial apertures. These characters supplement Mather's diagnosis of the genus and prove that it belongs to the family Septoporidae. Analysis of all other bryozoan species assigned to the genera Dictyocladia and Matheropora (Trizna 1939; Shulga-Nesterenko 1941; Nekhoroshev 1956; Balakin 1975) show that none belong to this genus. Thus the genus Matheropora is monotypic.
Sergey D. Scherbak, Institute of Hydrobiology of Academy of Sciences, Heroev Stalingrada ave., 12, Kiev, 254210, Ukraine; and Natalia V.Karaeva, Independent Environmental Safety Services, P.O. Box 836, Kiev, 252086, Ukraine
During periods of mass development of bryozoans, floatoblasts could affect the structural and functional characteristics of planktonic communities. As a constituent of the zooplankton, statoblasts are one of the food components of numerous fish species. A total of 240 intestines of carp (Cyprynus carpio L.) and goldfish (Carassius carassius (L.)) from four ponds in the Kiev region of the Ukraine were studied for evaluation of the trophic value and role of statoblasts in fish diets. Samples were collected from April to September. Floatoblasts of two species of phylactolaemate bryozoans -Plumatella fungosa (Pallas, 1768) and P. repens (L., 1758) -were recorded in the food bolus of carp and goldfish. The maximum of volume of floatoblasts (67%) in the intestines of goldfish feeding basically on planktonic crustaceans was found in July-August coinciding with the time of mass development of Plumatella. Most of the floatoblasts are not destroyed during passage through the fish intestine. An average of 85% (78%-91%) of floatoblasts retain their structure in the end part of the intestine, and only 15% are digested. Statoblasts should be considered as a facultative ingredient of fish foodstuffs. Given that statoblasts can pass through fish intestines and still remain viable, the introduction of fish may be one way of establishing bryozoan populations in water bodies where they were not previously found.
Tatiana A. Sharapova, Institute of Northern Development, Tyumen, Russia; and Alexander A. Protasov, Institute of Hydrobiology, Kiev, Ukraine
Bryozoans are a little-known group in the reservoirs of Western-Siberia. In zooperiphyton samples collected from different reservoirs in 1982-1996, we found five species: Paludicella articulata (Ehrenberg), Cristatella mucedo Cuvier, Plumatella fungosa (Pallas), P. repens (L.) and Fredericella sultana (Blumenbach). Plumatella fungosa was the most commonly encountered species. It was found in rivers (Ob, Irtysh, Tobol), channels and lakes, fouling wood, stones and shells of the living mollusc Anadonta. Plumatella repens was found less often, occurring in tributaries of the Ob and Irtysh rivers. Cristatella mucedo colonies were collected from ponds, and its statoblasts were constantly to be found in floodplain lakes from the south of Western-Siberia to the polar regions. Colonies of Paludicella articulata were found in the rivers Ob and Taz, their tributaries, and in the system of Tarmansky lakes. The species Fredericella sultana was rarely met in Western-Siberia: however, it was found in the north-west, in the lake belonging to the river Taz basin, and in the south-west, in the Shaitanskoje and Kopanetz lakes of the Tarmansky lake-bog system. This system is of particular interest. It consists of three lakes connected to each other by channels and surrounded by bogs. All five species of bryozoans were found there. The most abundant were settlements of Paludicella articulata (up to 6.1 grams per square metre), covering the submerged branches of willow and rhizomes of the previous year's generation. Bryozoan settlement began in spring at the end of May or the beginning of June. Colonies of Plumatella fungosa in lakes began developing later, at higher temperatures. Although rarer, settlements were larger, up to 32.7 grams per square metre. The northern boundary of distribution of Plumatella fungosa, Paludicella articulata and Fredericella sultana is presently situated at a latitude of about 67°N.
Natalya N. Shunatova, Department of Invertebrate Zoology, St Petersburg State University, St Petersburg, Russia
Observations on colonies of Schizomavella auriculata var. lineata were made during the summers of 1995-96 at the Marine Biological Station of St Petersburg State University in the White Sea (Chupa Inlet, Kandalaksha Bay). Colonies contained about 150-200 zooids and had several monticules formed by frontal budding. Passive chimneys situated in depressions between monticules were observed for the first time. On the summits of the monticules were situated feeding polypides with equi-tentacled lophophores, and on the sides of the monticules polypides with obliquely truncate lophophores having their longest tentacles directed towards the intermonticular depressions. After passing through the tentacle crowns, water moved down towards the depressions where there were no feeding polypides and where excurrent water outlets could be observed. This observation is contrary to previous research which has assumed that passive chimneys are located on the tops of the monticules. In addition a colony with passive chimneys situated in the depressions as well as on the tops of monticules was found. The proposed explanation for these observations is as follows. Water currents within the colony are connected with colony age and polypide degeneration-regeneration cycles. When colony reaches a particular age and size frontal budding commences. By this time the polypides on the monticules are just formed and feed actively. At the same time polypide degeneration begins in the depressions. Thus inhalent currents are observed on monticules and passive chimneys develop in the depressions between monticules. During the next stage of the polypide degeneration-regeneration cycle, newly regenerated polypides start to feed in the depressions. Simultaneously, polypide degeneration takes place on the monticules leaving no feeding polypides in these areas. Now the monticules function as exhalent chimneys, similar to those reported in other bryozoans. Thus colony-wide water current patterns in Schizomavella auriculata var. lineata depend on colony age and size.
Olga Sinitsina, Institute of Hydrobiology, Kiev, 254210, Ukraine
Hydroecological investigations in the Konin Lakes system (Poland) were carried out during 1994-1996. Due to the presence of discharge (warm) and inflow (cold) channels of the "Konin" and "Patnow" power plants and channels between five lakes, it is possible to regulate the water temperature in the whole system, especially in the case of very warm summers. Bryozoan communities occurred within the temperature range 24-35 °C. Of the two species of Bryozoa found in the bottom fauna and in the periphyton of channels, Plumatella fungosa was present only in the inflow channels. Total destruction of organic matter in communities with P. fungosa was 0.26-1.81 kJ/m³.h. At least 8-20% of the total destruction was represented by P. fungosa in the benthos and 33% in the periphyton. Rate of destruction in discharge channels was higher. The majority of the energy was transformed in the periphyton by Plumatella emarginata - 97-98.6% of the total oxygen use - 0.23-3.42 kJ/m³.h . Destruction in benthic communities by P. emarginata was 0.03 kJ/m³.h. Average energy flow through P. emarginata communities in discharge channels, considering the entire flooded area, was 66,300,000 kJ/day (1.33 tons C/day). Basic processes of production and energy dispersal by P. emarginata in the zoobenthos was 73%, and 6% in the periphyton, compared with 3-11% by bivalves (Dreissena polymorpha and Anodonta sp.). This data shows that the role of P. emarginata in the self-purification of the Konin Lakes is greater than that of bivalve communities; however, the two groups have different life strategies (P. emarginata has a short life-cycle and is an r-strategist).When P. emarginata decomposes up to the 144 kg C (1994 data) may be transferred to the water lake bed. Therefore, when developing measures for the management of water quality, the utilization of bryozoans must be taken into consideration.
Edward M. Snyder, Department of Physical Science, Sheperd College, Sheperdstown, WV 25443, USA; and Ernest M. Gilmour, Department of Geology, Eastern Washington University, Cheney, WA 99004, USA
A diverse and abundant assemblage of fenestrate Bryozoa characterizes the Guadalupian (Kazanian) Gerster Formation of northeastern Nevada. Comprehensive analysis of Gerster fenestrate Bryozoa was undertaken employing techniques which distinguish zoarial from zooecial characters both quantitatively and descriptively, and through three-dimensional reconstruction of the zooecial chamber shape and size. Further, unusual preservation in which zooecial chambers were selectively preserved allowed extremely accurate reconstruction of chamber shape and dimensions. Zooecial characters exhibit a lower intraspecies variation than zoarial characters, and are heavily relied upon in taxonomy.
A total of ten fenestrate species were identified in the Gerster Formation; of these Rectifenestella microretiformis Morozova, 1970; Wjatkella permiana Morozova, 1970; W. wjakensis (Netschajew, 1893); and Polypora soyanensis Morozova, 1970 are all described from Permian age materials in Russia, with most more specifically from the Russian platform. Rectifenestella microretiformis also occurs in Primor'e Province. All the above species are confined to the Lower Kazanian, except Wjatkella wjatkensis and also Polypora kasanensis Morozova, 1970, which occur throughout the Kazanian. Four new species (Rectifenestella n. sp. A, Wjatkella n. sp. A, Reteporidra n. sp. A, and Penniretepora n. sp. A) are recognized and have proven useful in biostratigraphic zonation.
The pronounced similarity between the Nevadan and Russian fenestrate Bryozoa suggests possible continuity of seaways between these now distant regions. Lack of similarity of Nevadan materials with those of similar age from West Texas suggests lack of a seaway connection between these areas.
Mary E. Spencer Jones, Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, U.K.
(POSTER)
Charles Darwin's voyage on H.M.S. Beagle and the subsequent publication of "Origin of Species" is regarded as a pivotal moment in science. Bryozoan specimens from this historic trip were passed to George Busk, who described several of them in the "Catalogues of Marine Polyzoa in the collection of the British Museum" (1852, 1854, 1875). More material was also received in 1899, after Busk's death, when his daughters presented his entire collection to The Natural History Museum in London. This study draws together all known records of bryozoan material collected by Charles Darwin and reviews their status.
Nils Spjeldnaes, Department of Geology, University of Oslo, P.O. Box 1047, Blindernm N-0316 Oslo, Norway
The geographical and stratigraphical distributions of Scandinavian Ordovician bryozoan faunas show some peculiar features, which - when properly explained - may throw light both on the development and biology of the bryozoans, and on the paleoenvironment, especially sedimentation, and climatic history. Some areas, such as Vestergötland in the Early and Middle Ordovician, are almost devoid of bryozoans, even if they are well represented in areas close by, like Öland, Dalarne and the Oslo Region. In the basal Middle Ordovician, the sparse fauna in the Oslo Region shows a relation to Britain (South Wales), and no other areas. In the Late Caradoc, there are two entirely different faunas in the Oslo Region, which both have many (but different) species in common with coeval Estonian faunas. This is remarkable as the Estonian faunas (of the Vasalemma and Rakvere Beds) are from a slowly sedimented carbonate platform, whereas the Norwegian faunas are found in rapidly sedimented basins - in dark shales in the Oslo-Asker Area, and clastic carbonates in the Mjøsa District. The most diverse bryozoan faunas are also found in the comparatively short time slots where the faunal exchange with North America was strongest. There is also a remarkable increase of "American" species from south to north in the Oslo Region. For at least some of these questions tentative solutions can be suggested, but others must wait for more detailed studies.
Tsuyoshi Suwa, Hiromi Ikezawa and Shunsuke F. Mawatari, Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060, Japan
Up to now, approximately 35 species of the genus Microporella (Microporellidae, Cheilostomata) have been described from many parts of the world. In Japan, Microporella ciliata and four other taxa of the genus, namely M. ciliata var. vibraculifera, M. dimidiata, M. echinata and M. orientalis, have been described so far (Ortmann 1890; Okada 1929, 1934; Okada and Mawatari 1937, 1938; Mawatari and Mawatari 1981; Mawatari et al. 1991). Based on the idea that the long coastal line of Japan must harbour more species of the genus, we conducted a faunal survey of Microporella along the coasts of Japan. As a result, Microporella echinata, M. neocribroides and eight new species were collected. Specimens were examined in particular relation with such new suites of characters as: (1) the skeletal parts of minute immature colonies and the ancestrula; (2) the morphology of uncleaned mature colonies examined using scanning electron microscopy; and (3) the cuticular mandibles of avicularia and opercula of orifices studied by light microscopy. Some of these, namely features of the ancestrulae, opercula and mandibles, were useful in discriminating species. The shapes of basal windows and the bottoms of frontal pores found in mature zooids are also new taxonomic characters utilized to give a standard style of description for species of Microporella.
Paul D. Taylor, Department of Palaeontology, The Natural History Museum, London SW7 5BD, U.K.; and Peter Allison, Department of Geology, Imperial College, Prince Consort Road, London SW7 2BP, U.K.
Although diverse bryozoan communities can be found today at many different latitudes, from the tropics to the poles, bryozoan skeletons are a significant component of carbonate sediments only in non-tropical regions. Therefore, incipient bryozoan limestones typify temperate or polar regions, and contrast in character with the coral and algal dominated limestones forming in the tropics. Sedimentologists and stratigraphers have used the occurrence of bryozoan limestones throughout the Phanerozoic to indicate a non-tropical regime, without considering whether the modern distribution of bryozoan-rich deposits has been true for the entire geological history of the phylum. A new database of bryozoan-rich deposits (bryozoan limestones, bryozoan marls etc) through geological time has been compiled to address this question. Individual occurrences have been mapped onto the best available palaeogeographical maps to infer the palaeolatitude of formation. Preliminary results of this analysis show that post-Palaeozoic bryozoan-rich deposits are invariably non-tropical, whereas Palaeozoic examples seem to have formed at a wider range of palaeolatitudes, including the tropics. The apparent post-Palaeozoic latitudinal restriction of sediment-producing bryozoans parallels the well-known and profound taxonomic changes seen in bryozoans between the Palaeozoic and post-Palaeozoic. It is suggested that a major shift in bryozoan macroecology may have occurred at this time, with the diversifying post-Palaeozoic bryozoan clades failing to repopulate the tropics to the same extent as the Palaeozoic clades that had become extinct.
Paul D. Taylor and Neale Monks, Department of Palaeontology, The Natural History Museum, London SW7 5BD, U.K.
The great majority of bryozoans are benthic. The genus Jellyella Taylor & Monks, 1997, provides an exception in that colonies usually foul floating objects and lead a pseudoplanktonic existence. One species, J. eburnea (Hincks), is most often encountered encrusting internal shells of the cephalopod Spirula spirula onto which it recruited after the death of the host. This bryozoan is very widespread geographically, particularly in the Indo-West Pacific, and has been recorded from Florida, South Africa, East Africa, Madagascar, Mauritius, Fiji, Australia, New Caledonia and New Zealand. With the exception of one colony of Electra, it is the only bryozoan found attached to Spirula shells in the museum collections available for study. Jellyella eburnea can also be found as an epibiont of living individuals of the floating snail Janthina. The second species assigned to Jellyella is the well-known Gulf-weed bryozoan 'Membranipora' tuberculata which typically fouls floating Sargassum. Jellyella has a twinned ancestrula and belongs to the Membraniporidae but differs in skeletal morphology, mineralogy and ultrastructure from both Membranipora and Biflustra. The existence of a long-lived planktotrophic larvae (cyphonautes) may be important in the success of Jellyella as a pseudoplanktonic animal, especially its ability to exploit substrata such as floating Spirula shells whose availability in time and space may be highly unpredictable.
Jonathan A. Todd, Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, U.K.
The ctenostomes are a major group (traditionally an Order) of primitive yet extant, unmineralized, marine bryozoans. Their existence has been consistently ignored in palaeoecological and phylogenetic studies despite their having a known range from the Early Ordovician. This is in large part due to the Palaeozoic taxa (and, until recently, the majority of Mesozoic taxa) being known solely from a limited diversity of borings. Nevertheless the borings are morphologically highly informative and are an untapped source of systematic information. When combined with a cladistic (PAUP) analysis of Recent ctenostome superfamilies they show that almost all of these may have originated by the Ordovician, implying vast ghost lineages. Fortunately such unmineralized encrusters may be systematically collected in large numbers, preserved by bioimmuration (organic overgrowth by a neighbouring skeletonized encruster).
Snapshots of Mesozoic marine hard substrate communities with their full complement of mineralized and unmineralized denizens, are routinely provided by bioimmuration. Many of these communities contained, and sometimes were dominated by, members of a single, highly diverse family of extant encrusting ctenostomes: the Arachnidiidae. Apart from revolutionising our knowledge of such communities, the apparent ubiquity of this clade in Mesozoic shelf seas forces a re-evaluation of the ecological importance of ctenostomes throughout much of the Phanerozoic. Preserved with submicron-scale fidelity, and sometimes with soft parts, many taxa are more completely known than their Recent counterparts. Stem-group members of this family, in particular, provide previously inaccessible information which necessitates a revision of current notions of bryozoan phylogeny and classification. Indeed, phylogenetic (PAUP) analysis reveals that the dominant and most speciose group of bryozoans today - the cheilostomes - nest amongst, and were derived from, probable stem-group arachnidiids.
Despite an often rich suite of characters, high-level cladistic analysis of post-Palaeozoic Bryozoa is still in its infancy. Study of bioimmurations has largely removed the taphonomic calcification barrier which had previously prevented a clear view of the inter-relationship of ctenostomes and cheilostomes, two of the three major extant groups of bryozoans.
Norbert Vavra, Institut für Palaeontologie, Geozentrum, Althanstrasse 14, A-1090 Wien, Austria
A well-preserved fauna from the Early Miocene (Eggenburgian) of Lower Austria offers opportunities for detailed taxonomic and ecological studies. Among the main faunal elements are most of those genera which are known to be typical components of the coralligenous biocoenosis. This richest circumlittoral Mediterranean community includes (together with special algae, serpulids, gorgonians and various corals) the following bryozoan genera: Adeonella, Frondipora, Myriapora, Pentapora, Sertella and Smittina. Of these only Pentapora is missing in the Austrian Miocene. In the Early Miocene Onychocella demarcqi shows a zoarial type comparable with Pentapora and may also have been important to some extent as a substratum for other bryozoans, very much like Pentapora in Recent faunas. This species of Onychocella is not only remarkable because of its type of zoarium but offers also information in respect to the reconstruction of ancient seaways connecting the Paratethys with the Western Mediterranean. Distinct indications for a symbiosis of Smittina cervicornis with a sponge (Halisarca? - see Harmelin et al. 1994) have been found in the Early Miocene too. Schizoporella geminipora - being very common in the Early Miocene of Austria - is discussed in connection with questions concerning phytal communities; the first appearance of Posidonia "meadows" is suggested for the Middle Miocene of the Central Paratethys on the basis of these bryozoan studies. By means of these and similar examples, general questions concerning possibilities and limits for palaeoecological conclusions and reconstructions are discussed.
(Studies supported by the "Fonds zur Foerderung der wissenschaftlichen Forschung, project P09561-GEO")
A. V. Vinogradov, Biology Department, Samara State University, Akademik Pavlov Street, 1, Samara, 443011, Russia
The Phylactolaemata have been known to science for 250 years ago. The taxonomic rank and structure of phylactolaemates is uncertain. Most investigators regard them as a class. However, it is the proposed to elevate them to the rank of superclass within the Bryozoa. The group Tentaculata, in which are included Bryozoa, Phoronida and Brachiopoda, is considered to be an anachronism. One opinion unites the Phylactolaemata, Gymnolaemata and Stenolaemata (the last two sometimes grouped together as Gymnolaemata) and Phoronida as a group. It has also been proposed to unite the Phylactolaemata and Inarticulata (Brachiopoda) in a subgroup together with fossil Hyolitha, Hyolithelmintida and some other forms. However, there are insufficient reasons for this grouping.
It is considered here that the Phylactolaemata may be divided into three orders, two of which are new. Some bryozoologists recognise two orders only. Family-level systematics is better understood, but the description of new families should continue. However, the existing genera of Phylactolaemata need verification. The description of new genera is continuing, including a check on the validity of earlier synonyms. A major problem concerns the choice of generic characters. The best features for determination of genera are morphometrical characters of the statoblasts and the ultramicrosculpture of their surfaces. True subspecies in both modern and fossil Phylactolaemata are unknown. Some old subspecies of Fredericella are now are determined as species. In conclusion, revision of the Phylactolaemata is needed.
L. A. Viskova, Paleontological Institute, Russian Academy of Science, 117647 Moscow, Russia
Traditionally all post-Paleozoic Stenolaemata have been included in one order, the Cyclostomata (=Tubuliporata). Our research (Viskova and Morozova 1988; Viskova 1992) has shown that they belong to at least three separate orders: Tubuliporida (cylindrical zooecial tubes; frontal walls; subcircular apertures; polymorphism - nanozooecia, gonozooecia), Cerioporida (cylindrical and prismatic zooecial tubes; frontal walls lacking; internal walls thick in exozone; subcircular apertures; polymorphism - exilazooecia, metazooecia, tergozooecia, alveoli, gonocysts, pores of different kinds), Melicerititida (club-shaped zooecial tubes; frontal walls as facets; subcircular, semicircular, rhomboidal apertures placed in the distal half of the facets; operculum-like formations; polymorphism - demizooecia, rostrozooecia, trifolizooecia, gonozooecia). In our opinion, each of these three orders represents an independent trend in the evolution of post-Paleozoic Stenolaemata, morphological differences among them being of no less degree than those among Paleozoic orders. For instance, nobody doubts that Paleozoic Cyclostomata and Trepostomida represent separate orders. Nevertheless, the post-Paleozoic suborder Cerioporina, close to Trepostomida, is placed by many workers in the order Cyclostomata together with Tubuliporina, despite the fact that in the process of the evolution they acquired several morphological innovations, such as brood chambers, etc., in addition to the differences inherited by them from their ancestors. No matter whether the Cerioporina originated from the Trepostomida (Borg 1944; Boardman 1984; Viskova 1992), or from the Tubuliporina (Brood 1976; Taylor 1996), we believe that it would not be reasonable to combine cerioporids and tubuliporids into one order Cyclostomata. As to the Melicerititida, its ordinal rank is emphasized by the extraordinary structure of the zooids.
L. A.Viskova and A. Yu. Ivantsov, Paleontological Institute, Russian Academy of Sciences, 117647 Moscow, Russia
A. M. Obut (1953) described some slightly plicated, ring-like flattened structures and their fragments built up from an amorphous coaly substance in Lower Kunda (Arenig-Llanvirn) rocks in the vicinity of Saint-Petersburg as Syringothenia bystrowi. The coaly substance contains flattened and regularly spaced calcite structures. These structures represent chambers filled with secondary calcite which could be the cavities of zooids of a colonial organism. We suggest that this organism may be referred to bryozoans with non-mineralized skeletons, whereas the coaly substance may represent the chitinous layer which formed a component of the outer and inner walls of the zooids. The calcite moulds most resemble the zooids of the extant bryozoan genus Alcyonidium. As in Alcyonidium they are rhomboid or rounded-hexagonal in shape. From the upper frontal side the zooid moulds are convex and possess mammilate processes (extant bryozoans possess the openings of zooids on the upper terminations of such processes). The lower basal side of the moulds is weakly convex, flat or slightly concave. The contacting zooid moulds with distinct boundaries are arranged in quincunx and form a single layer. Occasionally the line of the diagonal is disturbed by the intercalation (budding) of daughter chambers, and in some places by the closely-spaced zooids. In the latter case zooid moulds become sack-shaped and slightly erect or vertical. The colonies of these fossil non-mineralized bryozoans apparently grew through the distal and lateral budding of zooids, in a similar way to extant Alcyonidium. Dimensions of zooid moulds are similar to the average size of zooids of extant Alcyonidium. We suggest that this find, despite its early geological age, may be referred to Alcyonidium Lamouroux, 1813, the extant genus of non-mineralized bryozoans.
O. B. Weiss and L. A. Viskova, Paleontological Institute,Russian Academy of Sciences, 117647 Moscow, Russia
Stenolaemata belonging to the genera Multifascigera Orbigny, Cyrtopora Hagenow, Clinopora Marsson and Claviclausa Orbigny have been discovered in Danian and Montian deposits of Kazakhstan. These genera have traditionally been regarded as being Cretaceous in Western Europe. Branching colonies of Clinopora and club-like colonies of Claviclausa are represented by single specimens but features of their colonies and developmental patterns of their dimorphic zooecia are clearly expressed. The details of some colonial structures noticeably distinguish Paleocene species of these two genera from Cretaceous species. Bryozoa belonging to Multifascigera are characterised by composite multilayered colonies. Every layer is built of fungus-shaped subcolonies with isolated disk-like heads. Autozooecia are gathered into triangular fascicles diverging radially from the centre of the disc. The fascicles of preceding subcolonies are transformed into the stems of subcolonies of the following layer. Unlike Paleocene species, the Cretaceous Multifascigera subcolonies are formed by plates of irregular shape and their fascicles are arranged in oblique and alternating rows. Species of Multifascigera, Clinopora and Claviclausa are reported for the first time from the Paleocene, but bryozoans of Cyrtopora are previously known from the Danian of Mangyshlak (Viskova and Endelmann 1971) and the Crimea (Viskova 1972). The new finding differs from known Cyrtopora species in having a typically vertical arrangement of the autozooecial fascicles (pinnules). It should be added that previous finds in the Danian of the Crimea include stenolaemates of such "Cretaceous" genera as Cavarinella Marsson, Hemicellaria Orbigny, Filicea Orbigny, with Cavarinella and Desmepora Lonsdale in Mangyshlak (Viskova and Endelmann 1971; Viskova 1972). The Crimean species of Cavarinella has been found also in the Montian of Belgium (Voigt 1987). However, all of these genera are represented in the Paleocene by single species. They do not change the common picture of reduction in stenolaemate diversity after the global crisis at the Cretaceous-Paleogene boundary.
Eugene L. Yakovis, Laboratory of Marine Benthic Ecology, Department of Invertebrate Zoology, St Petersburg State University, StPetersburg, Russia
Fifty-nine bryozoan species, representing about half of the total species diversity, were found during an analysis of the structure of the fouling community associated with Balanus crenatus clusters. The investigation was carried out during the summers of 1993-96 in Solovetskiy Gulf (Onezhskiy Gulf, White Sea). Substratum type and the attachment site were documented for each epibiont. Populations of living and dead barnacle shells were analysed separately. The majority of bryozoan species found preferred the rostral and lateral plates of the barnacle shells. This may be caused simply by a preference for bottom surfaces of substrata since barnacles mostly orientate with their carinal plates upwards. Among the abundant bryozoan species only Scrupocellaria arctica is found slightly more often on the carina than on the rostrum. Seven bryozoan species (Dendrobeania fruticosa, Hippoporina propinqua, Porella smitti, Rhamphostomella bilaminata, R. ovata, Schizomavella auriculata lineata and Scrupocellaria arctica) are significantly more frequent on B. crenatus shells than on other types of substrata. Two of these (Dendrobeania fruticosa, Hippoporina propinqua), and also Smittina majuscula, prefer to inhabit the shells of living barnacles and are less abundant on dead shells. The improvement of bryozoan feeding or of colony cleaning by water flow induced by the feeding barnacle may explain this phenomenon. Tricellaria peachi and Escharella sp. are more abundant on dead barnacle shells. Escharella sp. may probably cause the death of young B. crenatus individuals by overgrowing them completely.
M. A. Zavjalov, Moscow State University, 117234 Moscow, Russia
The presence of the following stenolaemate bryozoans has been established in the Valanginian-Lower Hauterivian deposits of the Crimea: Filisparsa neocomiensis d'Orbigny, 1853; Heteropora arborea (Roemer, 1839); Cardioecia neocomiensis (d'Orbigny, 1853); Lichenopora pocillum d'Orbigny, 1850 and Meliceritites dendroidea (Keeping, 1883). The first three species have been recorded before by Favorskaya(1983), but M. dendroidea and L. pocillum are recognized for the first time. F. neocomiensis and M. dendroidea are the most interesting. The first species shows a regularity in the disposition of pseudopores in diametrical parallel rows. As for M. dendroidea, the most ancient examples of this species have been known until now from the Barremian (Pitt & Taylor 1990). The finding of M. dendroidea in the Valanginian-Lower Hauterivian of the Crimea may attest to an earlier appearance of the genus Meliceritites. All of the above mentioned species, except M. dendroidea, are known from Valanginian and Hauterivian deposits in France and Switzerland (Canu & Bassler 1926; d'Orbigny 1853; Walter 1972), and also from Lower Hauterivian deposits of north-western Germany (Hillmer 1971). Similarities between the Early Cretaceous bryozoans of the Crimea and contemporary bryozoans from western Europe provides evidence about links between basins of these distant regions.