Gomphoneis potapovae Kociolek & Kulikovskiy, 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 : 18

Gomphoneis potapovae Kociolek & Kulikovskiy , sp. nov. ( Figs 305–315 , 417–419 )

Valves lanceolate-clavate with apices rounded. Length 13–28 µm, breadth 4.0–6.0 µm. Axial area narrow, expanded to form a small X-shaped central area, bordered by 2–3 shortened striae on either side near the margin. Stigmoids wanting. Raphe weakly lateral, with external proximal raphe ends dilated, distal raphe ends deflected onto valve mantle. Costate striae radiate, except parallel towards the headpole. Striae 16–20/ 10 µm. Apical pore fields barely visible. Septa and pseudosepta present at poles.

In the SEM the central area appears to bear isolated areolae externally ( Figs 417, 418 ), but those are not visible internally ( Fig. 419 ). The external proximal raphe ends are dilated slightly, and the apical pore fields are positioned almost entirely on the valve mantle ( Fig. 417, 418 ). Internally there are prominent septa, and the recurved proximal raphe ends are evident ( Fig. 419 ).

Type:— RUSSIA: Lake Baikal , Middle Island , Ohlon Gate, 1998, Darwin Initiative sample ( COLO slide for Station 8, collection 8.0, holotype designated here (= Fig. 307 ); IBIW slide no. Station 8, collection 8.0m, isotype) .

Etymology:— Named in honor of our friend and colleague, Dr. Marina Potapova (Philadelphia) , for her many contributions to the study of diatoms.

Observations:— Differs from G. strelnikovae by the larger valves and rounded not protracted headpole.

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 17: SEM. Gomphoneis strelnikovae. Figs 412–416: Figs 412, 413: External valve views showing the raph brach with dilated proximal raphe ends. Even though the striae around the central area terminate with a single areolae, there are not stigmoids internally. The apical pore field is positioned entirely on the valve mantle, porelli do not extend onto the valve face. Figs 414–416: Internal views. The central nodule is not well distinguished from the rest of the central area, and bears the proximal raphe ends that recurved in the same direction. Helictoglossae and pseudosepta are present at the poles. G. potapovae. Figs 417–419: Figs 417–418: External valve views showing straight raphe with slightly dilated proximal ends. The doubly punctate striae end in single areolae; those around the central area appear larger than others. Porelli are located on the valve mantle. Fig. 4192: Internal valve view with septa evident at the poles, along with helictoglossae. The central nodule is raised internally, and bears the proximal raphe ends recurved in the same direction. G. sp. cf. reichardtii. Figs 420–421: Fig. 420: Internal valve view with 4 isolated stigmoids evident. Their openings are simple. The central nodule is small, and bears recurved proximal raphe ends. The poles have helictoglossae and pseudosepta. Fig. 421: External view showing the apical pore field restricted to the valve mantle. The raphe is slightly undulate, and the proximal raphe ends are dilated.