Crenotia tibetia Liu & Kociolek, 2024

Na, Xinyuan, Liu, Jiaming, Zhang, Ying, Kociolek, John Patrick, Kulikovskiy, Maxim, Lu, Xinxin, Sui, Fengyang, Zhu, Huan, Liu, Guoxiang, Fan, Yawen & Liu, Yan, 2024, A new species of genus Crenotia (Bacillariophyta) from Tibet, China, PhytoKeys 237, pp. 23-35 : 23

Crenotia tibetia Liu & Kociolek sp. nov.

Figs 1 , 2 , 3 , 4 , 5

Holotype.

Slide THXZ2021BYQX1-4#, the holotype specimen circled on the slide, illustrated here as Fig. 1A and 1A '; isotype, slide QX1-4#, illustrated here as Fig. 1C and 1C '.

Type locality.

China. Tibet, Anduo County, Nagqu City, hot spring, periphyton, 31°41'51.24"N, 91°51'20.52"E, 4570 m a.s.l., collected by Huan Zhu, 31 January 2021.

Description.

LM (Fig. 1 ). Frustule slightly bent along the transapical axis ( “V” shaped), monoraphid, with raphe valve concave, rapheless valve convex. Valve lanceolate with slightly protracted ends, slightly asymmetrical to the apical axis, apices nearly capitate. Length 11.8-19.7 μm, breadth 4.1-5.3 μm (n = 30). Raphe valve: straight raphe positioned in the middle of the valve, axial area lanceolate, with asymmetrical, rectangular to rhombic central area. Striae slightly radiating in the centre, becoming parallel towards the apices. Rapheless valve: Axial area lanceolate, central area expanded unilaterally to the margin. Striae 19-21 per 10 μm on both valves.

SEM (Figs 2 - 5 ). Raphe valve: Externally, raphe straight, proximal raphe ends slightly deflected to the same side, with distal raphe ends curved to the other side. Axial area lanceolate, nearly 1/3 of the valve width, formed by short striae along the margin. The 3 - 4 striae near the apices are biseriate and become uniseriate towards the valve centre. Areolae openings round to elongate, to irregularly-shaped externally. Internally, proximal raphe ends slightly bent to opposite side, helictoglossae slightly elongated. Areolae covered by hymens, forming two rows of “C” -shaped openings for each stria. Along the axial area, at the end of each stria, there is one horseshoe-shaped structure, open with fine radiating slit-like openings. One developing valve was observed; all the striae were biseriate.

Rapheless valve: Internally, axial area lanceolate, narrow at the apices and becoming wider towards the centre, centre area enlarged unilaterally and reaching the margin. Striae uniseriate to biseriate, mostly biseriate at the apices and becoming uniseriate at the centre. Areolae openings round to irregular in shape. Mantle and girdle bands without ornamentation.

Internally, the axial area is lanceolate, wide in the centre and enlarged at one side extending to the margin. Areolae were occluded by hymens with double rows of “C” -shaped openings; at the end of each stria, there is horseshoe-shaped structure, with fine slit-like openings. A developing valve was observed, all the striae were biseriate, with a "C- shaped structure at the end of each stria.

Etymology.

Named after the type locality from which it was found.

Figures

Figure 1. Crenotia tibetia sp. nov., LM. Raphe and rapheless valves from the type population. A, A' illustrations of the holotype. " = " means the raphe valve and rapheless valve are from the same frustule. Scale bar: 10 μm.

Figure 2. Crenotia tibetia sp. nov. SEM, external view of the raphe valve A external view of the whole valve B, C apices of the valve D magnification of areolae E central area of the valve F girdle view of the valve. Scale bar: 1 μm (A, B, C, E, F); 500 nm (D).

Figure 3. Crenotia tibetia sp. nov. SEM internal view of the raphe valve A internal view of the whole view B, C apices of the valve D central area of the valve internally E magnification of the areolae, showing the horseshoes areola at the end of striae F internal view of a developing valve. Scale bar: 1 μm (A, B, C, D, F); 500 nm (E).

Figure 4. Crenotia tibetia sp. nov. SEM external view of the rapheless valve A, B external view of whole valve C, D apices of the valve, showing the areolae. Scale bar: 1 μm.

Figure 5. Crenotia tibetia sp. nov. SEM internal view of the rapheless valve A internal view of the whole valve B apex of the developing valve C apex of the valve D magnification of the areolae, showing the horseshoe-shaped structure at the end of the areolae. Scale bar: 1 μm.