Type species: Nicholsonella ponderosa Ulrich, 1890
This genus includes the species:
| Nicholsonella acanthobscura | McKinney, 1971 | Ordovician Caradoc=Sandbian-Katian | USA Alabama |
| Nicholsonella adumbrata | Modzalevskaya, 1977 | Ordovician Ashgill=Katian-Hirnantian | Russia Tuva |
| Nicholsonella amplexa | Kopajevich, 1984 | Ordovician Ashgill=Katian-Hirnantian | Mongolia |
| Nicholsonella antiqua | Yabe & Hayasaka, 1920 | Ordovician | China |
| Nicholsonella divulgata | Ernst & Key, 2007 | Ordovician Caradoc-Ashgill=Sandbian-Katian | France |
| Nicholsonella genuina | Astrova, 1965 | Early Ordovician Tremadocian-Floian | Russia Novaya Zemlaya |
| Nicholsonella houi | Yang, 1957 | Ordovician Arenig=Floian-Dapingian | China |
| Nicholsonella inflecta | McKinney, 1971 | Ordovician Caradoc=Sandbian-Katian | USA Alabama |
| Nicholsonella irregularis | Loeblich, 1942 | Ordovician Caradoc=Sandbian-Katian | USA Oklahoma |
| Nicholsonella laminata | Ulrich, 1893 | Ordovician Caradoc=Sandbian-Katian | USA Minnesota |
| Nicholsonella mariae | Astrova, 1965 | Ordovician Caradoc=Sandbian-Katian | Russia Siberia |
| Nicholsonella mariae orientalis | Rozman et al., 1970 | Late Ordovician | Russia |
| Nicholsonella moniliformis | Loeblich, 1942 | Ordovician Caradoc=Sandbian-Katian | USA Oklahoma |
| Nicholsonella nelidovi | Nekhorosheva, 1965 | Early Ordovician | Russia Novaya Zemlaya |
| Nicholsonella ottawaensis | Wilson, 1921 | Ordovician Caradoc=Sandbian-Katian | Canada Ontario |
| Nicholsonella parafrondifera | McKinney, 1971 | Ordovician Caradoc=Sandbian-Katian | USA Alabama |
| Nicholsonella parva | Owen, 1965 | Silurian Wenlock | England |
| Nicholsonella parvula | Bassler, 1928 | Ordovician Ashgill=Katian-Hirnantian | Canada Quebec Anticosti Is. |
| Nicholsonella peculiara | Yaroshinskaya, 1984 | Late Ordovician | Mongolia |
| Nicholsonella peculiaris | Cumings & Galloway, 1913 | Ordovician Ashgill=Katian-Hirnantian | USA Indiana |
| Nicholsonella petaloides | Astrova, 1965 | Middle Ordovician | Russia Siberia |
| Nicholsonella polaris | Modzalevskaya in Modzalevskaya & Nekhoroshev, 1955 | Late Ordovician Sandbian | Russia Siberia |
| Nicholsonella polymorpha | Kopajevich, 1984 | Ordovician Ashgill=Katian-Hirnantian | Mongolia |
| Nicholsonella ponderosa | (Ulrich, 1890) | Ordovician | USA Illinois |
| Nicholsonella pseudopulchra | Modzalevskaya, 1977 | Ordovician Caradoc=Sandbian-Katian | Russia Tuva |
| Nicholsonella pulchra | Ulrich, 1893 | Ordovician Caradoc=Sandbian-Katian | USA Tennessee |
| Nicholsonella recta | Ernst & Key, 2007 | Ordovician Caradoc-Ashgill=Sandbian-Katian | France |
| Nicholsonella ringuebergi | Bassler, 1906 | Silurian Wenlock | USA New York |
| Nicholsonella vaupeli | (Ulrich, 1883) | Ordovician Caradoc=Sandbian-Katian | USA Ohio |
| Nicholsonella vaupeliformis | Modzalevskaya in Modzalevskaya & Nekhoroshev, 1955 | Middle-Late Ordovician | Russia |
| Nicholsonella wilsonae | Fritz, 1957 | Ordovician Caradoc=Sandbian-Katian | Canada Ontario |
Nicholsonella at University of Georgia.
Nicholsonella from Nashville region: at University of Georgia.
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