Gomphoneis cf. subcapitata, Kociolek, Kulikovskiy & Solak, 2013

Kociolek, John P., Kulikovskiy, Maxim S. & Solak, Cüneyt N., 2013, The diatom genus Gomphoneis Cleve (Bacillariophyceae) from Lake Baikal, Russia, Phytotaxa 154 (1), pp. 1-37 : 14

Gomphoneis cf. subcapitata ( Figs 175–192 , 406)

Valves small, lanceolate to nearly elliptical-clavate, headpole rounded, footpole narrowly rounded. Length 8.0– 15.5 µm, breadth 2.5–3.5 µm. Axial area narrow, straight, expanded to form a wide rectangular central area extending to the margin with1–2 shortened striae. 4 stigmoids positioned at the end of striae occur around the central area. Raphe barely lateral, more or less straight. Striae costate, slightly radiate, 13–16/ 10 µm. Apical pore field indistrinct. Septa and pseudosepta at the poles, small.

In the SEM the valve interior of this small diatom has a rather prominent central nodule, with recurved proximal raphe ends, and surrounded by 4 stigmoids. The stigmoid openings are more or less rounded. Large helictoglossae are present at the poles, and there is a small pseudoseptum at each end of the valve (Fig. 406).

Observations:— We will continue to examine specimens of this relatively common species before deciding whether to include all similar specimens within a concept of G. subcapitata , or to segregate them into a separate species. Valve shape with respect to how developed the protracted headpole might be (less protracted in these specimens) differentiates this group from G. subcapitata .

Figures

PLATE 7: LM. Figs 169–174: Gomphoneis metzeltinii sp. nov. Fig. 169 is of the holotype. Figs 175–192: G. cf. subcapitata. Figs 193– 200: G. subcapitata sp. nov. Fig. 200 is of the holotype. Figs 201–214: G. inconspicua sp. nov. Fig. 201 is of the holotype. Figs 215– 222: G sp. cf. subcapitata. Figs 223–228: G. reichardtii sp. nov. Fig. 223 is of the holotype. Figs 229–237: G. sp. cf. skabitchevskii. Figs 238–250: G.sp. cf. skabitchevskii. Figs 251–260: G. skabitchevskii sp. nov. Fig. 258 is of the holotype. Figs 261–282: G.sp. cf. reichardtii. Scale bar = 10 µm for all figures.