Vanni nilgiriensis ( Roux, 1931 )

Vanni nilgiriensis ( Roux, 1931) View in CoL

( Fig. 2 View Figure 2 )

Paratelphusa (Liotelphusa) nilgiriensis Roux, 1931: 56 View in CoL .

Gubernatoriana nilgiriensis — Bott, 1970a: 45. — Bott, 1970b: 336. — Srivastava, 2009: 29 (list).

Vanni nilgiriensis View in CoL — Bahir and Yeo, 2007: 341. — Ng et al., 2008: 68 (list). — Dev Roy, 2012: 187 (list).

Material examined. INDIA. Kerala: Wayanad district — 1 male (cw 15.56 mm, cl 11.35 mm, ch 6.56 mm, fw 4.94 mm) and 3 females (cw 14.30–16.78 mm, cl 10.43–12.11mm, ch 5.87–7.11 mm, fw 4.72–5.29 mm), Kambamala (11.869°N, 75.942°E; altitude 816 m), 26 October 2018, coll. P.S. Sujila (ZSI-WRC C.1825); 4 males (cw 13.38–18.34 mm, cl 9.80–12.60 mm, ch 5.83–8.37 mm, fw 4.24–5.46 mm) and 9 females (cw 14.62–19.08 mm, cl 10.55–13.29 mm, ch 6.41–8.10 mm, fw 4.62–5.95 mm), Pilakavu (11.867°N, 75.985°E; altitude 859 m), 9 October 2018, coll. P.S. Sujila (ZSI-WRC C.1826) GoogleMaps .

Comparative material. INDIA. Karnataka: Kodagu district — 1 male (cw 24.42 mm, cl 17.24 mm, ch 9.28 mm, fw 7.99 mm), Ezhilaturn, Thalacauveri Wildlife Sanctuary (12.384°N, 75.494°E; altitude 1185 m), 6 November 2013, coll. P.M. Sureshan (ZSI-WGRC IR/INV/9197) GoogleMaps .

Diagnosis. Carapace broader than long (cw/cl = 1.4–1.5), low (ch/cw = 0.4); epigastric cristae distinct, slightly anterior to postorbital cristae; postorbital cristae rugose, not reaching epibranchial tooth; external orbital angle broadly triangular, with long outer margin, approximately 4–5 times length of inner margin; epibranchial tooth low, blunt; epistomal median lobe lacking median tooth ( Fig. 2A, B View Figure 2 ). Ambulatory legs short, stout ( Fig.2A, C View Figure 2 ). Suture between male thoracic sternites s2/s3visible as narrow groove, reaching lateral margins; suture between male thoracic sternites s3/s4 only visible as 2 short lateral grooves ( Fig. 2C View Figure 2 ). Male pleon moderately broad, almost triangular; pleonal somite 6 trapezoidal, broader than long, slightly shorter than telson ( Fig. 2C View Figure 2 ). Male telson narrow, longer than broad at base, with slightly concave lateral margins ( Fig. 2C View Figure 2 ). Male sternopleonal cavity short, extending up to imaginary line joining submedian part of cheliped coxae ( Fig. 2C View Figure 2 ). G1 moderately stout, almost straight, with inner margin characteristically curved or angled just below juncture between terminal and subterminal segments; terminal segment almost conical, short, approximately 0.3times length of subterminal segment, distal third distinctly narrower than basal two-thirds; subterminal segment moderately stout ( Fig. 2D View Figure 2 ). G2 longer than G1, approximately 1.2–1.4 times length of G1; distal segment long, approximately 0.4–0.5 times length of basal segment ( Fig. 2E View Figure 2 ).

Remarks. The present specimens of V. nilgiriensis from Wayanad district of Kerala are very similar to the male lectotype in carapace morphology. These specimens are relatively smaller (cw 15.56–18.34 mm) than the lectotype (cw 24.70 mm) and the paralectotype (cw 21.00 mm) from Nilgiris of Tamil Nadu. The G2 distal segment in the present specimens, however, is relatively shorter, i.e., approximately 0.4 times the length of the basal segment (vs. relatively long, approximately 0.5 times the length of the basal segment in the lectotype; see Bahir and Yeo, 2007: fig. 35G). In addition, all the present specimens have a relatively shorter G2, approximately 1.2 times the length of the G1 ( Fig. 2D, E View Figure 2 ) (vs. a relatively long G 2 in lectotype, approximately 1.4 times the length of G1; see Bahir and Yeo, 2007: fig. 35C, G). An adult male from Kodagu district of Karnataka (ZSI-WGRC IR/INV/9197) also has a shorter G2 distal segment (approximately 0.4 times the length of the basal segment) like that of the present specimens from Kerala.The lone specimen from Karnataka, however, differs from the present specimens in the length of the G2, which is about 1.3 times the length of the G1. Despite these variations in the G2 of V. nilgiriensis , all the present specimens from Kerala and the material from Karnataka are conspecific with the lectotype from Tamil Nadu due to the similarity in overall carapace physiognomy and G1 structure. Although information on variations in G2 structure is unavailable for V. nilgiriensis and its congeners, some species (e.g., Travancoriana schirnerae Bott, 1969 ) of the morphologically related genus, Travancoriana Bott, 1969 , depict intraspecific variations in the length of the G2 distal segment ( Bahir and Yeo, 2007).

Geographical distribution. Vanni nilgiriensis is currently known from the Western Ghats of Karnataka (Kodagu district), Kerala ( Wayanad district ), and Tamil Nadu ( Nilgiris district ) ( Fig.2F View Figure 2 ).Both the Coorg plateau (the Western Ghats part of Kodagu district ) and Wayanad plateau are connected with each other and the Nilgiri mountains , which all together form a continuous mountain chain with similar zoogeography ( Bhimachar, 1945). Vanni nilgiriensis is probably restricted to these mountain ranges .