Pilarta Bahir and Yeo, 2007

Pati, S. K., Rajesh, L., Raj, Smrithy, Sheeja, V. U., Kumar, A. Biju & Sureshan, P. M., 2017, Karkata, a new genus of gecarcinucid freshwater crab with two new species, and four new species of Pilarta Bahir and Yeo, 2007 and Cylindrotelphusa Alcock, 1909 (Decapoda: Brachyura) from Kerala, India, Journal of Natural History (J. Nat. Hist.) 51 (23 - 24), pp. 1295-1330 : 1307-1309

Pilarta Bahir and Yeo, 2007

Pilarta Bahir and Yeo 2007: 332

Type species

Pilarta anuka Bahir and Yeo, 2007 , by original designation.

Diagnosis (revised from Bahir and Yeo 2007)

Carapace not very deep, broader than long (cw/cl = ca. 1.3–1.4), sparsely to densely punctate; dorsal surface convex in frontal view; anterolateral and posterolateral margins glabrous or with dense setae; front slightly broad (fw/cw = ca. 0.3); epigastric and postorbital cristae visible, but not well developed; external orbital angle broadly triangular, with long outer margin, ca. 3–4 times length of inner margin; epibranchial tooth very small, blunt, cleft visible; cervical grooves distinct, broad; H-shaped groove shallow to deep; frontal median triangle with dorsal margin only; epistome posterior margin with prominent, rounded or broadly triangular median lobe ( Figures 7 (a,b) and 9(a,b); see Bahir and Yeo 2007, figs 25(a,i) and 26(a,b)). Ambulatory legs with dense setae on external surfaces of dactylus, propodus and carpus ( Figures 7 (f) and 9(f); see Bahir and Yeo 2007, figs 25(e,i) and 26(a)). Sutures between male thoracic sternites s2/s3 and s3/s4 undiscernible as grooves ( Figures 7 (c,g) and 9(c,g); see Bahir and Yeo 2007, figs 25(c) and 26(c)). Male abdomen broadly T-shaped; fifth abdominal somite distinctly broader than long; sixth abdominal somite broader than long, slightly shorter or distinctly longer than telson; telson as long as broad or broader than long ( Figures 7 (c,h) and 9(c,h); see Bahir and Yeo 2007, figs 25(d) and 26(c)). Third maxilliped exopod lacking flagellum ( Figures 7 (i) and 9(i); see Bahir and Yeo 2007, fig. 25(b)). G1 stout, straight, with short or slightly long terminal segment, ca. 0.3–0.4 times length of subterminal segment, tip distinctly narrow; subterminal segment with broad median portion ( Figures 8 (a–c) and 10(a–c); see Bahir and Yeo 2007, fig. 25(f,g)). G2 with long or very long distal segment, ca. 0.4–0.6 times length of basal segment ( Figures 8 (d) and 10(d); see Bahir and Yeo 2007, fig. 25(h)).

Remarks

Pilarta is closely related to Karkata gen. nov., Snaha , Ghatiana , Gubernatoriana and Inglethelphusa mainly due to the absence a flagellum on the third maxilliped exopod and almost straight G1 terminal segment. Pilarta is distinguished from these genera by its densely setose ambulatory legs ( Figures 7 (f) and 9(f); see Bahir and Yeo 2007, fig. 25(e)) (vs sparsely setose ambulatory legs; see Bott 1970, pl. 34, fig. 25 for Inglethelphusa ; Bahir and Yeo 2007, fig. 28(a) for Snaha ; Pati and Sharma 2014, fig. 2(a) for Ghatiana , fig. 6(a) for Gubernatoriana ). In addition, like Ghatiana , Gubernatoriana and Inglethelphusa , Pilarta can be differentiated from Karkata and Snaha by the undiscernible suture between the male thoracic sternites s2/s3 and s3/ s4 ( Figures 7 (g) and 9(g) for Pilarta ; see Bott 1970, pl. 34, fig. 26 for Inglethelphusa ; Bahir and Yeo 2007, fig. 25(c) for Pilarta ; Pati and Sharma 2014, fig. 3(a) for Ghatiana , fig. 7(a) for Gubernatoriana ) (vs prominent suture between the male thoracic sternites s2/s3 and s3/s4, Figures 2 (g) and 4(g) for Karkata ; see Bahir and Yeo 2007, figs 28(c), 29(a) and 30(c) for Snaha ).

Pilarta now includes three species: P. anuka Bahir and Yeo, 2007 , P. aroma sp. nov., and P. punctatissima sp. nov.

Ecological notes

Pilarta punctatissima can be found in rocky crevices along slow-flowing streams in lowlying areas, while P. aroma is found underneath cobblestones in fast-flowing cold

streams in the highlands. Pilarta anuka has been reported from dry streams in highland areas, living under stones in moist soil ( Bahir and Yeo 2007).

Geographic distribution

The genus is known only from the Western Ghats of Kerala at Thattekkad Bird Sanctuary of Ernakulam district, and Ponmudi and Agasthyamala of Thiruvananthapuram district.

Figures

Figure 2. Karkata ghanarakta gen. et sp. nov., holotype male (ZSI, WRC-C.1523). (a) Dorsal view; (b) frontal view; (c) ventral view; (d) right or major cheliped; (e) carpus of major cheliped; (f) right ambulatory leg (p3); (g) anterior thoracic sternites (s1–s4); (h) abdominal somites 5, 6 and telson; (i) left third maxilliped. Scale bars: a–c = 10 mm; d, f = 5 mm; e, g–i = 2 mm.

Figure 7. Pilarta aroma sp. nov., holotype male (ZSI, WRC-C.1529). (a) Dorsal view; (b) frontal view; (c) ventral view; (d) left or major cheliped; (e) carpus of major cheliped; (f) right ambulatory leg (p3); (g) anterior thoracic sternites (s1–s4); (h) abdominal somites 4–6 and telson; (i) left third maxilliped. Scale bars: a–c = 10 mm; d, f = 5 mm; e, g–i = 2 mm.

Figure 8. Pilarta aroma sp. nov., holotype male (ZSI, WRC-C.1529). (a) Dorsal view of left G1; (b) dorsal view of left G1 terminal segment; (c) ventral view of left G1; (d) left G2. Scale bars: a, c, d = 1 mm; b = 0.5 mm.