Stephanoarcus Genkal, Kulikovskiy, Glushchenko & Tseplik, 2025

Genkal, Sergei, Glushchenko, Anton, Tseplik, Natalia & Kulikovskiy, Maxim, 2025, A reinvestigation of Stephanodiscus triporus (Stephanodiscaceae, Mediophyceae) with the description of Stephanoarcus gen. nov., Phytotaxa 712 (1), pp. 1-17 : 2-3

Stephanoarcus Genkal, Kulikovskiy, Glushchenko & Tseplik gen. nov.

Type species (here designated): Stephanoarcus triporus (Genkal & Kuzmin) Genkal, Kulikovskiy, Glushchenko & Tseplik comb. nov.

Description

Cells low cylindrical to disc-shaped. The valves are circular, flat, convex or concave. Valve structure consisting of radial ribs or hyaline interfascicles and fascicles of areolae between them that consist of single areolae near the center, and 2–4 areolae per fascicle towards the edge of the valve. Fascicles continue onto valve mantle without significant change in structure of areolae. In the center of the valve there is one or several areolae located randomly; rarely the center is hyaline. Areolae are locular, with a foramen on the external surface of the valve, and a domed velum on the inside. Interfascicles usually end in spines or spinules at the junction between valve face and mantle, less often the spines are absent. Valves with a single valve face fultoportula with 2–4 satellite pores. Marginal fultoportulae have 3 satellite pores on the inside of the valve and open on the outside at the edge of the valve with an arch-like structure. A single rimoportula is located in the ring of spines, externally forming a tube and opening as a labiate slit internally.

Etymology: The genus name reflects the presence of arch-like structures at the valve edge as one of the defining features and the similarity between the new genus and Stephanodiscus . This genus name is treated as masculine.