Adlafia kociolekii C.Radhakrishnan, Sudipta K.Das, C.E.Wetzel & B.Karthick, 2023

Se. Wetzel & Karthick, Balasubramanian, 2023, Adlafia kociolekii sp. nov. (Bacillariophyceae): a new naviculoid diatom from the Eastern Himalayas, India, Phytotaxa 595 (1), pp. 62-72 : 64-66

Adlafia kociolekii C.Radhakrishnan, Sudipta K.Das, C.E.Wetzel & B.Karthick sp. nov. ( Figs 2–43 )

Description: —LM ( Figs 2–28 ): Valves lanceolate to linear-lanceolate, elliptical, with acute apices: valve length 16– 53.5 μm, width 6–10.5 μm (n=25). Raphe slightly lateral and straight, inflated proximal ends, very slightly deflected to primary side, distal ends deflected in opposite direction. Striae uniseriate, 26–30 in 10 μm, composed of round areolae, radiate at centre, parallel to convergent near apices. Valves with narrow axial area [sternum], central area broad and elliptical in large valves, narrow, straight in smaller ones. Voigt discontinuity is clearly discernible towards both poles.

SEM ( Figs 29–43 ): Externally, the raphe system is narrow and not prominent ( Figs 29–30 ). Proximal raphe ends slightly dilated and teardrop-like ( Figs 34–35 ). Hook-like distal ends bend in the opposite direction ( Figs 30–33 ). Uniseriate striae, areolae mostly covered with hymenes, clearly visible only when thoroughly oxidized ( Figs 29–31 ). The shape of the areolae is round to oval near mantle and oval to elongate near axial area. Areolae more regularly arranged on primary side; less regular on secondary side ( Fig. 29 ). Areolae more elongate near the central area ( Fig. 34 ).

Internally, raphe is thin and almost straight and the sternum more elevated ( Figs 36–37 ). Distal raphe ends slightly bent, with long raised helictoglossae ( Figs 38, 40–41 ). Proximal raphe ends are deflected in the opposite direction to the distal ends ( Fig. 36 ). Striae form round to elliptical areolae opening on entire valve ( Figs. 42–43 ). Mantle is deep, a rows of areolae is present near to distal ends and terminating with helictoglossae ( Fig. 40 ).

Type locality: Panchgotey , Kyongnosla Alpine Sanctuary , Sikkim, India, 27.3197° N, 88.5455° E, 3888 m a.s.l.; attached to moss (epibryophytic) patches on rocks ( Agharkar Herbarium of Maharashtra Association ( AHMA) #2421, holotype, an example illustrated in Figure 2 ; Central National Herbarium ( CAL), Isotype no. CAL /ALG.60) .

Etymology: The species name is in the honour of eminent diatomologist Dr John Patrick Kociolek from CU Museum of Natural History, the University of Colorado at Boulder, USA.

Ecology and distribution: The type material was aerial in occurrence. The species was also found epilithic in freshwater and in subaerophytic habitats in northeast India. A small population of the taxon was found epipsammic habitat of a stream near Khamrang, Mizoram. Rare occurrences of the taxa were also noted on wet walls in Angori (Meghalaya) and Keitum (Mizoram). The details of the distributions of the taxon in various parts of northeast India, along with the other diatoms growing in consortium, are presented in Table 1 .

Figures

FIGURES 2–28. Light microscopic images of Adlafia kociolekii sp. nov. Valve show the size diminution series and Voigt discontinuity (arrowhead). Figs 2–18. Valves sampled from Sikkim (AHMA Acc. 2421). Figs 19–23. Valves sampled from Mizoram (AHMA Acc. 2547). Fig. 24. Valves sampled from Mizoram (Acc. 2624). Figs. 25–28. Valves sampled from Meghalaya (AHMA Acc. 2812). (Scale bar 10 μm).

FIGURES 29–35. SEM of Adlafia kociolekii sp. nov. Figs 29–31. Showing the whole view of the external valve, raphe structure, areolae patterns, girdle structure and Voigt discontinuity (arrowhead). Figs 32–33. Valve apices show distal raphe deflection along with round areolae patterns. Figs 34–35. The central part of the valve shows the proximal raphe ending and hymenated areolae. Scale bars 2 μm (29–35).

FIGURES 36–43. SEM of Adlafia kociolekii sp. nov. Figs 36–37. Showing the whole view of the internal valve, proximal (arrow), distal raphe deflection, and internal areolae opening. Figs 38, 40–41. Apices of the internal valve showing the distal raphe ends with helictoglossae. Fig. 39. The central view of the internal valve shows the proximal raphe ending (arrow). Figs 42–43. Internal view showing the areolae patterns and transapical areolae structure. Scale bars 2 μm (36–43).