Gomphoneis strelnikovae 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 : 19-20

Gomphoneis strelnikovae Kociolek & Kulikovskiy , sp. nov. ( Figs 316–327 , 412–416 )

Valves lanceolate-clavate, with headpole protracted and apices rounded. Length 12.0– 18.5 µm, breadth 3–5 µm. Axial area narrow, straight, expanded transversely to form a narrow, rectangular central area, bordered by 1–2 shortened striae on either side. Stigmoids wanting. Raphe lateral, with external proximal raphe ends dilated slightly, distal raphe ends deflected onto mantle. Costate striae radiate, except at the headpole where they are parallel to weakly convergent. Striae 19–22/ 10 µm. Apical pore fields absent from valve face. Septa and pseudosepta present at poles.

In the SEM the valve exterior has what appear to be isolated areolae in the central area, of differing sizes. The proximal raphe ends are dilated, and the distal raphe ends are deflected before the valve terminus. Apical pore fields are found on the valve mantle only ( Figs 412–413 ). Internally, the proximal raphe ends are recurved, and helictoglossae are prominent ( Figs 414–416 ). Pseudosepta are small at the valve apex ( Figs 414–416 ).

Type:— RUSSIA: Lake Baikal , Middle Island , Ohlon Gate, 1998, Darwin Initiative sample ( COLO slide for Station 8, number 8.0, holotype designated here (= Fig. 319 ); IBIW slide no. Station 8, number 8.0m, isotype) .

Etymology:— Named in honor of Dr. Nina I. Strelnikova , for her many contributions to the study of diatoms.

Observations:— Gomphoneis strelnikovae differs from G. potapovae by having protracted apices and a valve outline that is more rounded, not angular.

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.