Gomphoneis capitata Kociolek & Kuliovskiy, 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 : 20

Gomphoneis capitata Kociolek & Kuliovskiy , sp. nov. ( Figs 335–352 , 392–395 )

Valves lanceolate-clavate, with headpole protracted, nearly rostrate, footpole protracted, rounded. Length 15– 19 µm, breadth 3–4 µm. Axial area very narrow, straight, expanded transversely to form a rectangular central area bordered on each side near the margin by a shortened stria. Stigmoids indistinct in the central area, sometimes only 2 stigmoids evident. Raphe barely lateral, straight, with external proximal raphe ends dilated slightly. Striae costate, radiate to nearly parallel in the center, parallel to nearly convergent towards the poles. Striae 15–18/ 10 µm. Apical pore field indistinct. Septa and pseudosepta small at both poles.

Internally, valves of G. capitata appear to express only two of the isolated stigmoids ( Figs 393, 394 ). Other features of the valve interior include proximal raphe ends recurved in the same direction, helictoglossae aligned with the axis of the raphe, and pseudosepta at the apices ( Figs 392–394 ). Externally, the raphe has prominently dilated proximal ends and distal ends that are barely deflected onto the mantle ( Fig. 396 ). Striae are doubly-punctate and terminate near the axial area with one or two areolae. The apical pore fields look like they are condensed striae ( Fig. 396 ).

Type:— RUSSIA: Lake Baikal , Middle Island , Ohlon Gate, 1998, Darwin Initiative sample ( COLO slide for Station 8, number 8.1, holotype designated here (= Fig. 336 ); IBIW slide no. Station 8, number 8.1m, isotype) .

Observations:— This species is more linear, narrower, and has more protracted apices than G. fourtanierae .

Figures

PLATE 8: LM. Figs 283–286: Gomphoneis baicaliana sp. nov. Fig. 285 is of the holotype. Figs 287–304: G. fourtanierae sp. nov. Fig. 288 is of the holotype. Figs 305–315: G. potapovae sp. nov. Fig. 307 is of the holotype. Figs 316–327: G.strelnikovae sp. nov. Fig. 319 is of the holotype. Figs 328–334: G. minuscula sp. nov. Fig. 333 is of the holotype. Figs 335–352: G. capitata sp. nov. Fig. 336 is of the holotype. Scale bar = 10 µm for all figures.

PLATE 14: SEM. Gomphoneis metzeltinii. Figs 389–391: Extenal valve views. Figs 389, 390: Whole valve views should fine striae and indistinct stigmoids. Proximal raphe ends are dilated slightly. Fig. 391. Footpole shows the rounded porelli of the apical pore field appear as condensed striae. G. capitata. Figs 392–396: Figs 392–395: Internal valve views. Figs 392–394: Entire valve views. Fig. 392: Specimen with girdle bands shows septa at the poles, wide, rectangular central area and central nodule with recurved proximal raphe ends. Fig. 393: Specimen lacking girdle bands revealing the smaller pseudosepta at the poles. The helictoglossae are evident also. Only two stigmoid openings are evident around the central nodule. Fig. 394: Specimen without girdle bands, showing pseudosepta, recurved proximal raphe ends on small central nodule, and helictoglossae at the poles. Fig. 395: Internal valve view showing only two prominent stigmoidal opening. The appear simple, without occlusions. Fig. 396: External valve view. The valve has proximal raphe ends that are prominently dilated, and has 2 types of stigmoidal openings, one larger and one smaller.