Luticola goeppertiana

Valves are lanceolate, with rounded and slightly protracted apices. In larger cells, the valve margins are less elliptic and the apices are less protracted, and in some specimens, are narrowly rounded. The axial area is narrow, linear, and expands near the central area. The central area is a bowtie shape. The central area is bordered by 2-4 single areolae on each valve margin. The striae are punctate and radiate throughout. A single, isolated, slit-like, transapically elongated stigma is located in the central area halfway between the valve center and the margin. Raphe branches are straight. The proximal raphe ends deflect to the side opposite of the stigma. The distal raphe ends are hooked and deflected toward the same side as the proximal raphe ends, then hooked towards the opposite side onto the valve mantle.

There has been nomenclatural confusion surrounding Luticola goeppertiana. The basionym is Stauroneis goeppertiana (Bleisch ex Rabenhorst) 1861, which was later transferred to Navicula, as Navicula goeppertiana (Bleisch) H.L. Smith 1876. However, as noted by Patrick and Reimer (1966), Stauroneis goeppertiana and Navicula mutica var. goeppertiana were both synonyms of Navicula mutica. The type specimens of L. goeppertiana and L. mutica differ in morphology (Levkov et al. 2013). Luticola mutica is more linear, whereas L. goeppertiana is more lanceolate. Striae on L. goeppertiana are more dense than on L. mutica. Furthermore, the stigma of L. mutica is an elliptic shape, while L. goeppertiana has a transapically elongated stigma.

Until recently (Rarick et al. 2017), L. goeppertiana was invalid because Round et al. (1990) did not provide a full and direct citation of the basionym when transferring N. mutica var. goeppertiana to L. goeppertiana. The valid transfer of Stauroneis goeppertiana to Luticola goeppertiana (Bleisch) D.G.Mann ex J.Rarick, S.Wu, S.S.Lee and Edlund 2017 was made, so the name is now valid as L. goeppertiana (Rarick et al. 2017).