Oricymba sagarensi, C.Radhakrishnan, Kociolek & B.Karthick, 2018

Radhakrishnan, Cheran, Kulikovskiy, Maxim, Glushchenko, Anton, Kuznetsova, Irina, Kociolek, Patrick & Karthick, Balasubramanian, 2018, Oricymba sagarensis (Gandhi) comb. nov., an endemic diatom from the Western Ghats, India, Phytotaxa 382 (3), pp. 267-274 : 269

Oricymba sagarensi s (Gandhi) C.Radhakrishnan, Kociolek & B.Karthick, comb. nov. (Figs 2–21)

Basionym: Cymbella sagarensis in Gandhi 1959, The Journal of Indian Botanical Societ y, p. 322, figs 24–25 (Gandhi H.P., 1959. FreshWater Diatoms from Sagar in Mysore State, The Journal of Indian Botanical Societ y, Vol XXXVIII, No 3, 305–331).

Synonym: Cymbella sagarensis f. gracilis in H.P. Gandhi 1959. ‘’ The Journal of Indian Botanical Societ y, p. 323, fig 44 (Gandhi H.P., 1959. Fresh-Water Diatoms from Sagar in Mysore State, The Journal of Indian Botanical Societ y, Vol XXXVIII, No 3, 305–331).

Lectotype (designated here):— [illustration] Fig 24–25 in Plate II in Gandhi (1959).

Epitype (designated here):— sample and slide “Sr-123 Rivulet pools in the rocky bed with Podostamads encrustations 12-1-1955 ”. The sample was collected by H.P. Gandhi from the Sharavathi River, near Sagar, in Karnataka (then Mysore) State, India, 12 January 1955. Epilithic material deposited in Diatom Collection at AHMA, Agharkar Research Institute, Pune, India

ORIGINAL DESCRIPTION: Valves 19–38 µm long and 8–10 µm broad, subsymmetrical dorsal side slightly more convex than the ventral, somewhat straight in the middle with abruptly narrowed shortly rostrate, acutely rounded ends, fairly wide linear central area on ventral side dilated with distinct stigma. Striae 8–9 in 10 µm slightly radiate and distinctly lineate ( Gandhi 1959).

LM (Figs 2–11): Valve lanceolate, slightly dorsiventral with acute apices. Dorsal margin more arched than the ventral margin. Length 20.5–34.0 µm, width 9–11 µm. Raphe lateral, externally raphe curved towards the ventral side and proximal raphe ends slightly ventrally deflected. External distal ends hooked towards dorsal side. Axial area lanceolate, central area rhomboid in shape with 1 short stria on the dorsal side and 3–5 short striae on the ventral side. Isolated stigma is located on the ventral side. Striae slightly radiate throughout the valve, 9–10 in 10 µm. Striae lineolate and areolae clearly visible, 30–35 in 10 µm.

SEM Figs (12–21): In external view, marginal ridge of silica prominent to indistinct. Valve surface flat, lacking any depression-like structures. External proximal raphe ends expanded and slightly deflected to the ventral side, distal raphe ends deflected to the dorsal side of the valve (Figs 12). Striae uniseriate, extending to the mantle (Fig. 15). Areola openings rectangular in shape and curved areolae located near the axial area (Fig. 15). Apical pore fields present on both apices (Figs 12, 17, 19). A small row of poroids present on the girdle bands. A distinct isolated stigma present on the ventral side. Internally, central raphe endings covered by an over-growth of silica; distinct separate ends not observed. Distal raphe ends terminate as small helictoglossae (Figs 17, 19, 21). Central area with two narrow stigma openings on the ventral side of the valve (Figs 17, 18). Stigma with fine ingrowths from the perimeter. Internal areolae openings also with fine ingrowths along the margin. Internal opening of apical pore field prominent.