Stauroneis lacuspowaiensis Wadmare & B.Karthick nom. nov., stat. nov. (Figs 1–18, Fig. 4 represents the lectotype)

Basionym: — Stauroneis phoenicenteron f. capitata in Gonzalves & Gandhi 1953, The Journal of Indian Botanical Societ y, p. 256, fig. 92 (here reproduced as Fig. 1)

Heterotypic synonym: — Stauroneis nobilis f. capitata H.Kobayasi (in Kobayasi & Ando 1977)

Type:— INDIA. Mumbai (then Bombay), Maharashtra. Powai Lake pavements having encrustations with dead vegetable matter, 19°7’37.2” N, 72°54’14.4” E, Mr. H. P. Gandhi on 6 th March 1945.

Lectotype (designated here):—Agharkar Research Institute (AHMA) Gandhi Collection! Slide- Sr 5, here illustrated as Fig. 4.

Description:—LM (Figs 1–8): Valves narrowly linear-lanceolate, having large, capitate apices with slight undulate sides (Fig. 5, arrow). Length 98.5–103.0 µm, breadth 16.5–18.0 µm. Axial area broad widening near centre. Stauros slightly broad, rectangular. Raphe thick with straight central raphe ends, and sickle-shaped terminal raphe fissures with bifurcation (Fig. 7, arrowhead). Striae parallel at centre and radiate towards apices, 18–23/10 µm. Areolae irregularly punctate (Fig. 4, double arrowheads), discernible in LM. (n= 21).

SEM (Figs 9–18): Externally (Figs 9–14), central raphe ends terminating on stauros (Figs 9, 10, 12). Raphe filiform (Fig. 12). Terminal raphe fissures sickle-shaped, continuing onto mantle (Figs 11, 13). Striae uniseriate, composed of irregularly placed, transapically elongated, slit-like areolae (Fig. 14, double arrowheads). Internally (Figs 15–18), stauros small, thickened and elevated with tunnel gap (Figs 15, 17, arrowheads). Terminal raphe fissures terminating onto helictoglossae (Figs 15, 16, 18). Areolae rounded to transapically elongated, 16–20 in 10 µm (Fig. 17, double arrowheads).

Remarks:—Valve dimensions of the specimens examined in the current study have a smaller size range than the dimensions given by H. P. Gandhi in the original description length 113.4–120.0 µm; width 21.6 µm (see Table 1). In addition, previous studies based on Gandhi’s material observed certain morphometry discrepancies (Karthick & Kociolek 2012, Kale et al. 2017).

Etymology:—The specific epithet “ lacuspowaiensis ” refers to the type locality Powai Lake, Mumbai, where H. P. Gandhi originally collected the sample.