Gliwiczia tenuis Kulikovskiy, Lange-Bertalot & Witkowski, 2013

Kulikovskiy, Maxim, Lange-Bertalot, Horst & Witkowski, Andrzej, 2013, Gliwiczia gen. nov. a new monoraphid diatom genus from Lake Baikal with a description of four species new for science, Phytotaxa 109 (1), pp. 1-16 : 6-8

Gliwiczia tenuis Kulikovskiy, Lange-Bertalot & Witkowski sp. nov. Figs 43–66

Frustules with a horse shoe-like internal cavum at both raphid and rapheless valve as characteristic of the genus. Valves broadly elliptical with broadly rounded ends. Length 7–13 µm, breadth 4.6–8 µm.

LM, raphe valve ( Figs 56–58 ): Raphe filiform, straight central ends slightly expanded, distal ends indistinct. Axial area narrow, linear. Central area forming a narrow, ca. 0.5 µ m broad stauros at both sides but unilaterally obscured by the elliptical cavum. Striae radiate throughout, becoming progressively stronger radiate to the ends, 28–33 in 10 µm. Areolae not discernible.

LM, rapheless valve ( Figs 43–55 ): Axial and central area merging into a wide elliptical space, striae therefore restricted to a marginal zone. No stauros interrupts the striae opposite to the side with the cavum. Striae 21–24 in 10 µm. Areolae not discernible.

SEM, raphless valve, internal view ( Figs 59–64 ): Sternum with raphe vestiges visible as a shallow elevation above the central axial area. The cavum is comparatively short, restricted to the marginal zone. A stauros is barely or indistinctly developed. A gap between the striae opposite to the cavum is lacking regularly. Areolae 50–60 in 10 µm.

SEM, raphe valve, internal view ( Fig. 65 ): Central raphe ends deflected clearly to opposite sides. The stauros together with the raphe sternum is strongly elevated above the internal valve surface. Cavum present extended from the centre nodule to the valve margin. Areolae uniseriate, small, approximately circular.

SEM, raphe valve, external view ( Fig. 66 ): Raphe with small central pores and more or less distinctly to opposite sides deflected distal ends that may be pore-like expanded at junction between valve face and mantle. The central area in a form of stauros appears clearly asymmetrical becoming expanded towards the margin at that side where the cavum occurs internally. Areola foramina are circular and open.

Type: slide no. 15645m (holotypus here designated see Fig. 46 ) in collection Maxim Kulikovskiy, I.D. Papanin Institute for Biology of Inland Waters , Russian Academy of Sciences ( IBIW) 20.07.1965, leg. A.P. Skabitschewsky.

Isotype: slide no. 15645a in collection Andrzej Witkowski, Institute of Marine Sciences, University of Szczecin (SZCZ).

Distribution: As yet known from the Lake Baikal.

Etymology: tenuis in Latin means smaller one.

Figures

FIGURES 43–62: Gliwiczia tenuis sp. nov. Figs 43–66: Figs 43–55: Valve view of rapheless valves. Fig. 43: arrow indicates presence of cavum in sternum valve. Figs 56–58: Valve view of raphe valves. Fig. 58: arrow indicates presence of cavum in raphe valve. Figs 59: Internal valve view of rapheless valve. Fig. 60 Internal view of valve part with cavum. Figs 61, 62. Internal view of areolae covered by circular foramina, come off from areolae in fig. 61 (43–58: LM; 59–62: SEM). Scale bar: 10 µm.

FIGURES 63–66: Gliwiczia tenuis sp. nov. Figs 63–66: Fig. 63–64: Internal view of rapheless valves note shorter striae in central part of valve opposite cavum. Fig. 65. Internal view of raphe valve note presence of cavum. Fig. 66: External view of raphe valve. It is questionable whether this valve belongs to G. tenuis sp. nov. (SEM).