Nupelaceae, TSEPLIK & GLUSHCHENKO & MALTSEV & GENKAL & NERGUI & KULIKOVSKIY, 2025

TSEPLIK, NATALIA, GLUSHCHENKO, ANTON, MALTSEV, YEVHEN, GENKAL, SERGEY, NERGUI, SONINKHISHIG & KULIKOVSKIY, MAXIM, 2025, Molecular investigation of Nupela mongolica sp. nov. (Bacillariophyceae) with the description of the family Nupelaceae fam. nov., Phytotaxa 681 (2), pp. 186-198 : 193

Nupelaceae fam. nov.

The modern system of families in diatoms was established by Round et al. (1990). Since then, many new genera have been described; these genera were either assigned to families that were set in Round et al. or noted as having uncertain taxonomic position. With the development of molecular methods, they were also used to determine the position of some genera ( Kulikovskiy et al. 2019, 2020; Schimani et al. 2024). The exact position of Nupela was undetermined since its description due to its unique combination of features. Cox (2015) placed this genus in the family Brachysiraceae , even though Nupela does not conform to the description of the family and does not share many features with Brachysira (Kulikovskiy et al. 2020) . The structure of pore occlusions in Nupela and Brachysira is somewhat similar because in both genera the hymenes cover the areolae fully and extend beyond the bounds of individual areolae, forming a continuous belt (coalescing hymenes according to Potapova 2011). However, Brachysira is characterised by internal hymenes that are transapically elongated (as shown in Round et al. 1990), while in Nupela the hymenes are external, more kidney-shaped, covering the crater-like areolae and extending onto the valve face ( Potapova 2011; Kulikovskiy et al. 2020). Later, Kulikovskiy et al. (2016) suggested Nupelaceae as a provisional name, which was based on the crater-like areolae with external hymenes being characteristic only for Nupela and not present in any other pennate diatoms. Molecular data supports this idea, since it demonstrated that Nupela forms a completely separate evolutionary lineage (Kulikovskiy et al. 2020); the positioning of Nupela within the Brachysiraceae was disproved by this study, because on the phylogenetic tree these two genera are positioned quite far from each other. In our study we have added a new strain of Nupela to the analysis, and it confirmed the results from previously conducted research. With both morphological and molecular data demonstrating the separate position of Nupela , we suggest a new family Nupelaceae fam. nov. to include this genus.