Cymbella pavanaensis A.Vigneshwaran, Kulikovskiy, Kociolek & B.Karthick, 2019

Vigneshwaran, Anbukkarasu, Kulikovskiy, Maxim S., Glushchenko, Anton, Kociolek, John Patrick & Karthick, Balasubramanian, 2019, A new species of Cymbella (Bacillariophyceae, Cymbellaceae) from the Pavana River, Western Ghats, India, Phytotaxa 395 (3), pp. 209-218 : 211-212

Cymbella pavanaensis A.Vigneshwaran, Kulikovskiy, Kociolek & B.Karthick sp. nov. ( Figs 1–36 )

LM ( Figs 1–28 ): Valve outline elliptic-lanceolate, slightly asymmetric to apical axis. Dorsal margin distinctly convex. Ventral margin slightly convex, with broadly rounded to narrowly rounded apices. Length 18–22 μm, breadth 5–6 μm. Length to breadth ratio 3.6–3.7 (n=70). Axial area narrow, straight, following curvature of raphe branches, not forming central area. Raphe lateral to filiform positioned near middle valve, arched, proximal ends deflected ventrally. Striae nearly parallel, becoming radiate near to apices, ventral striae 12–14 in 10 μm at middle, at ends 14–16 striae in 10 μm. One stigma present at ventral side.

SEM external valve views ( Figs 29–32 ): Striae extend to valve face towards mantle on both dorsal and ventral margins. Striae comprised of apically-elongate, lineolate areolae. Length of areolae decreases towards valve margin to center near central striae. One small elliptical stigma opening present at central area differentiated slightly to apicallyelongated areolae. Raphe undulated, with proximal ends dilated and deflected towards dorsal side ( Fig. 31 ). Distal raphe ends deflected towards dorsal margin ( Fig. 29 ), not bisecting apical pore fields. Apical pore fields present on both sides of valve ( Fig. 29 ). Porelli similar in structure to areolae.

SEM internal valve views ( Figs 33–36 ): Uniseriate striae appear as areolate alveoli. One small stigma opening present at ventral side ( Fig. 35 ). The margins of stigma alveolus have small, tooth-like projections. Internally proximal raphe endings hidden by overgrowth of silica ( Fig. 35 ). Distal raphe terminates in small visible helictoglossae ( Figs 34, 36 ). Helictoglossae slightly offset towards dorsal side. Small apical pore fields present in each valve apex, Porelli appearing rounded internally and differentiated from areolae ( Fig. 34 ).

Type (designated here): — INDIA. Pavana River, Pimpri-Chinchwad, Pune , Maharashtra, India (18°38’25.1”N, 73°44’52.2”E). Samples collected by Mr. Samadhan Pardhi on 01 July 2017. (Holotype AHMA! 1414 = Fig. 6 ; Isotype CAL! CAL /ALG. 057) .

Habitat: —Epilithic. Environmental measurements include a pH of 7.64, a total phosphorus ( TP) of 0.44 mg /L, a total nitrogen ( TN) 0.01 mg /L; dissolved oxygen: 4.92 mg /L; conductivity: 140 μS/cm; water temperature: 32.1°C.

Etymology: —Species epithet refers to the name of the river from which this new taxon is identified.

Figures

FIGURES 1–28. Cymbella pavanaensis sp. nov., LM (DIC). Figs 1–25. Valve views, showing the valve variability of the holotype population. Scale bar = 10 μm. Fig 6. Micrograph of holotype specimen. Fig. 26, 27. Showing the proximal raphe ends in LM. Fig. 28. Girdle view of the frustule.

FIGURES 29–32. Cymbella pavanaensis sp. nov., SEM, external views. Scale bars = 1 μm. Fig 29. External view showing the general morphology, raphe, lineolate areolae. Fig. 30, 32. Pole with dorsally deflected raphe fissure and apical pore field. Fig. 31. Central area with dorsally deflected raphe endings and stigma.

FIGURES 33–36. Cymbella pavanaensis sp. nov., SEM, internal views. Scale bars = 1 μm. Fig 33. Internal view of a whole valve. Fig 35. Internal view of the valve center showing internal stigma openings. Fig 34, 36. Internal view of valve ends with dorsally curved, knob-like helictoglossae.