Gomphoneis cf. reichardtii, 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 : 17

Gomphoneis cf. reichardtii ( Figs 261–282 , 420–421 )

Valves linear-elliptical clavate, tumid at center, with headpole barely protracted and rounded, footpole narrowly rounded. Length 7–24 µm, breadth 3–5 µm. Axial area narrow, expanded laterally to form a rectangular to bow-tie shaped central area that is usually asymmetrical, with one side of the central area being slightly larger than the other, bordered by 1–2 shortened striae that are more coarsely arranged than the other striae. 4 stigmoids occur around central area, positioned at ends of striae. Raphe is broadly lateral, undulate, with external proximal raphe ends rounded. External distal raphe ends extend straight onto the valve mantle at both apices. Costate striae radiate, except at headpole where they become nearly parallel. Striae 13–17/ 10 µm. Apical pore field small. Septa and pseudosepta at the poles, indistinct.

This species has a valve interior with a small central nodule and relatively large helictoglossae ( Fig. 420 ). Stigmoidal opening are simple and round. The proximal raphe ends are deflected in the same direction. Pseudosepta are present at the apices ( Fig. 420 ). The exterior of the valve has indistinct stigmoids, small, round, slightly dilated proximal raphe ends ( Fig. 421 ). The apical pore field is located on the mantle ( Fig. 421 ).

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.

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.