Gomphonema microlaticollum Kulikovskiy, Kociolek & Solak, 2015

Kulikovskiy, Maxim S., Kociolek, John P., Solak, Cüneyt N. & Kuznetsova, Irina, 2015, The diatom genus Gomphonema Ehrenberg in Lake Baikal. II. Revision of taxa from Gomphonema acuminatum and Gomphonema truncatum-capitatum complexes, Phytotaxa 233 (3), pp. 251-272 : 260

Gomphonema microlaticollum Kulikovskiy, Kociolek & Solak , sp. nov. ( Figs 176–190 , 282–288 )

Valves clavate, slightly swollen at the center of the valve, strongly asymmetrical to the transverse axis. Length: 14.0–25.3 μm, breadth: 7.3–8.7 μm. Headpole truncate, broadly rounded and narrower footpole. Axial area is narrow. Central area small, with striae on each side of the central area irregularly longer and shorter. A stigma is present in the central area close to the proximal raphe endings. Striae punctuate, distinctly radiate, 13–14 in 10 μm. SEM: Valves externally with punctate to doubly punctate striae, ending in a single areola at the axial area. Areolae with C - shaped occlusions ( Figs. 282–285 ). Raphe strongly undulate. Proximal raphe ends dilated, while stigma opening is small and round. Internally, there is a narrow pseudoseptum and helicoglossae at the poles ( Figs 286–288 ).

Type: — RUSSIA. Lake Baikal: pool near bay, fouling on tree submerged in water, 52º 27.042’ N, 106º 53.215’ E, M. Kulikovskiy, 14 July 2011 (holotype: IBIW! slide no. 18589 = Fig. 178 ).

Etymology: —Epithet refers to the smaller size but similarity with G. laticollum .

Observations: —This taxon is easily distinguished from G. laticollum by its smaller size and higher number of striae in 10 μm.

Figures

FIGURES 167–186. LM. 167–175.Gomphonema laticollum. 176–190.Gomphonema microlaticollum sp. nov. Fig.178 is of the holotype. Scale bar = 10 μm.

FIGURES 187–227. LM. 191–213. Gomphonema cf. truncatum. 214–227. Gomphonema paracapitatum sp. nov. Fig. 214 is of the holotype. Scale bar = 10 μm.

FIGURES 281–285. SEM. 280–281. Gomphonema laticollum, internal views. 280. Footpole, raphe terminating in helictoglossa. There is a pseudoseptum present.282–285.Gomphonema microlaticollum sp. nov., external views. 282, 284. Whole valve views. 283, 285. Central areas with biseriate striae, round stigma opening and dilated proximal raphe ends evident. Scale bars = 1 μm in Figs 280, 281, 283, 285; 2 μm in Figs 282, 284.

FIGURES 286–291. SEM. 286–288. Gomphonema microlaticollum sp. nov. Internal views. 286.Whole valve view showing outline. 287. Headpole with helictoglossa and narrow pseudoseptum present. 288. Footpole showing offset helictoglossa and pseudoseptum. 289–291. Gomphonema cf. truncatum, external views. 289. Whole valve view. 290. Central area. Biseriate striae become uniseriate near the axial area. Areolae are C-shaped. Dilated proximal raphe ends and small, round stigma opening are evident. Raphe is undulate. 291. Headpole with striae and deflected distal raphe end evident. Scale bars = 5 μm in Figs 286, 289; 1 μm in Fig. 287; 0.5 μm in Fig. 288; 2 μm in Figs 290, 291.