Geissleria baicalosimilis Kulikovskiy, Gusev, Andreeva & Annenkova, 2014

Kulikovskiy, Maxim, Gusev, Evgeniy, Andreeva, Svetlana & Annenkova, Natalia, 2014, Phylogenetic position of the diatom genus Geissleria Lange-Bertalot & Metzeltin and description of two new species from Siberian mountain lakes, Phytotaxa 177 (5), pp. 249-260 : 252

Geissleria baicalosimilis Kulikovskiy, Gusev, Andreeva & Annenkova sp. nov. Figs 2–19

LM, live cells (12–14): One large chloroplast with two lobes.

LM ( Figs 2–11 ): Valves elliptic, ends protracted and capitate. Length 14.0–15.6 µm, breadth 5–6 µm. Raphe filiform, axial area narrow, central area small and irregularly bordered. One isolated pore near the middle of central nodule, on primary part of valve. Striae weakly radiate, 16–17 in 10 µm.

SEM, external view ( Figs 15, 16, 18 ): The raphe slit is straight without visible sternum. One isolated pore near central nodule. Central raphe ends straight. Terminal raphe ends deflected towards the secondary side of valve and continue onto mantle. Striae uniseriate throughout. Areolae present as short slits, 65–70 in 10 µm of stria. Annulus presents as two rows of larger then in stria areolae, apically elongated. In every row from 3 to 4 apically elongated areolae are present.

SEM, internal view ( Figs 17, 19 ): Raphe slit lying in internal sternum.Central raphe endings straight, terminal ends terminate in small helictoglossae. Elongated subpolar areolae (annulus) with warty outgrowths. Internally no hymens or occlusions are observed on the areolae.

Type:— RUSSIA: Lake Baikal , pool near Bay, fouling on tree submerged in water, at 8 km from Enkhaluk village, N 52027.042 E 106053.215, 14.07.2011, leg. M. Kulikovskiy ( IBIW slide no. 18589/B088, holotype designated here (= Fig. 3 )), COLO slide 18589/B088p is isotype .

Etymology: —Epithet refers to the similarity with Geissleria similis (Krasske) Lange-Bertalot & Metzeltin (1996: 68) and the type locality.

Observations: This species is very similar to G. similis . However it is easy distinguish this species by both quantitative and qualitative features. G. baicalosimilis sp. nov. has finer striae in 10 µm (16–17, not 15) and more finer areolae in 10 µm of stria (65–70, not 60) than in G. similis . Striae in the central area of G. similis are long and almost reach central nodule. Additionally, only two elongate pores (one in each stria) at the end of valve present in G. similis . G. baicalosimilis sp. nov. possesses six or more elongated pores.

Figures

FIGURES 2–19. Geissleria baicalosimilis sp. nov. Figs 2–19: Figs 2–10: Valve view. Fig. 11: Frustule view of girdle. Figs 12–14: Live cells with chloroplast structure, explanation in the text. Figs 15, 16: External valve view, note isolated pore in fig. 16 (arrow).Fig. 17: Internal valve view, note isolated pore structure (arrow). Fig. 18 External view of valve end, note structure of elongated subpolar pores (annulus). Fig. 19. Internal view of valve end, note annulus structure with warty outgrowths (2–14: LM; 15–19: SEM). Scale bar for LM: 10 μm.