Gecarcinucidae Rathbun, 1904

Z, Sameer Kumar Pati, 2025, Taxonomic revision of the freshwater crab genera Travancoriana Bott, 1969, and Vanni Bahir & Yeo, 2007 (Crustacea: Decapoda: Gecarcinucidae), with descriptions of eight new genera and two new species from the Western Ghats, southern India, Zootaxa 5634 (1), pp. 1-77 : 6-10

Family Gecarcinucidae Rathbun, 1904

Genus Travancoriana Bott, 1969

( Figs. 2, 3)

Travancoriana Bott, 1969: 361 .

Travancoriana – Bott 1970b: 40.— Bahir & Yeo 2007: 316.— Ng et al. 2008: 68 (list).— Srivastava 2005: 117 (list); 2009: 29 (list).— Pati & Sharma 2013: 275.— Klaus et al. 2014: 654 (list).— Prabakar 2017: 28 (list).— Rajesh et al. 2017: 134 (list).—Pati 2020: 162 (list).— Pati & Pradhan 2020: 555836 (list).— Pati & Yeo 2022: 2 (list).— Sruthi & Thirunavukkarasu 2022: 460 (list).

Type species. Travancoriana schirnerae Bott, 1969 , by original designation; gender of genus feminine.

Diagnosis. Large sized crabs (maximum CW 55.3 mm). Carapace relatively broad (CW/CL = ca. 1.3–1.5), relatively low ( CH /CW = ca. 0.4), with moderately convex lateral margins; frontal medial triangle incomplete, lateral margins indiscernible; postorbital cristae well-developed, reaching lateral margins of carapace; external orbital angle broadly triangular, with long outer margin, ca. 4 times length of inner margin; epibranchial tooth low, located at same level of postorbital cristae; epistome posterior margin with well-developed, trapezoidal medial tooth and strongly sinuous lateral lobes ( Fig. 2A, B). Maxilliped 3 with well-developed flagellum on exopod (see Bahir & Yeo 2007: fig. 7C). Chelipeds relatively stouter in adult males ( Fig. 2A). Ambulatory legs relatively stout, shorter, glabrous ( Fig. 2A). Male s2/s3 visible as broad groove, not reaching edge of sternum; male s3/s4 visible as shallow, complete groove, reaching edge of sternum ( Fig. 2C). Male sternopleonal cavity relatively short, reaching to imaginary line joining anterior part of cheliped coxae ( Fig. 2C). Male pleon relatively narrow, with strongly concave lateral margins; pleonal somite 6 subquadrate, relatively narrow, proximal width ca. 1.1 times medial length ( Fig. 2C). Male telson longer than broad, medial length ca. 1.2 times proximal width ( Fig. 2C). G1 relatively slender; ultimate article conical, relatively slender, distally gently curved inwards, relatively short, ca. 0.3–0.4 times length of penultimate article; penultimate article moderately stout ( Fig. 3A, B). G2 as long as G1, ca. 1.0 times G1 length; ultimate article long, ca. 0.5–0.6 times length of penultimate article ( Fig. 3C).

Remarks. Bott (1969) established Travancoriana with a new species, Travancoriana schirnerae , as the type species. Subsequently, Bott (1970b) included Paratelphusa ( Barytelphusa) carli Roux, 1931 , Paratelphusa ( Barytelphusa) pollicaris Alcock, 1909 , and Paratelphusa ( Liotelphusa) malabarica Henderson, 1912 , in Travancoriana . Paratelphusa ( Liotelphusa) travancorica Henderson, 1913 , was already added to the genus by Bott (1970a). Bahir & Yeo (2007) revised Travancoriana and recognised five species (including Paratelphusa ( Barytelphusa) pollicaris ) in it, as they have assigned Paratelphusa ( Barytelphusa) carli to Vela Bahir & Yeo, 2007 , and Paratelphusa ( Liotelphusa) malabarica and Paratelphusa ( Liotelphusa) travancorica to Vanni . Pati & Sharma (2013) later described a new species of Travancoriana . Paratelphusa ( Barytelphusa) napaea ( Alcock, 1909) (originally in Potamon Savigny, 1816 ) was included in the checklist of Ng et al. (2008) without explanation. The generic position of Potamon napaeum Alcock, 1909 , was recently clarified by Pati & Yeo (2022) who transferred it to Maydelliathelphusa Bott, 1969 , instead. The following six species are thus known in Travancoriana s. lat.: T. charu Bahir & Yeo, 2007 ; T. convexa ( Roux, 1931) ; T. granulata Pati & Sharma, 2013 ; T. kuleera Bahir & Yeo, 2007 ; T. pollicaris ( Alcock, 1909) ; and T. schirnerae Bott, 1969 ( type species) ( Bahir & Yeo 2007; Pati & Sharma 2013).

All the known species of Travancoriana s. lat. recognised by Bahir & Yeo (2007) and Pati & Sharma (2013) possess a distinctly transverse carapace, well-developed postorbital cristae, a broadly triangular external orbital angle with a long outer margin, and a long ultimate article of the G1 ( Figs. 2A, 3A, 4A, B, E, F, 5A, D, 6A, F, 7A, 8A, 9A, F, 10A, 11A, 12A, B, E, H, 13A). Travancoriana , however, is polyphyletic, with both T. charu and “ T. pollicaris ” [= Palaniana convexa ( Roux, 1931) comb. nov.; see remarks below for Po. pollicaris ( Alcock, 1909) comb. nov. and see remarks of Bahir & Yeo (2007) for T. convexa ] forming separate clades from T. schirnerae in the phylogenetic tree of Klaus et al. (2014: fig. 1). Some species of Vanni also possess the diagnostic characters of Travancoriana sensu Bahir & Yeo (2007) (see remarks section for Vanni ). It is, therefore, necessary to redefine the genus with additional generic suite of characters and also taking into consideration the geographical distribution of the congeners.

Travancoriana charu and T. pollicaris possess a male s3/s4 only visible as two short lateral depressions ( Figs. 4D, H, 6C), with the G1 penultimate article being distinctly slender ( Figs. 5A, B, D, E, 6F, G); in contrast, the male s3/s4 is visible as a complete groove ( Figs. 2C, 7C, 9C, 10D, 12D), and the G1 penultimate article is much stouter in other species of Travancoriana s. lat. ( Figs. 3A, B, 8A, B, 9F, G, 11A, B, 12H, I, 13A, B). These two species can be further distinguished from Travancoriana s. str., which only includes the type species, T. schirnerae , by the trapezoidal and relatively broad male pleonal somite 6, with the proximal width ca. 1.3 times the medial length ( Figs. 4D, H, 6C, E) (versus subquadrate and relatively narrow male pleonal somite 6, with the proximal width ca. 1.1 times the medial length; Fig. 2C). As a result, T. charu and T. pollicaris are hereby transferred to a new genus, Ponmudiana gen. nov., with the former species as the type herein designated. Although Ponmudiana gen. nov. and Travancoriana s. str. are both known from the Western Ghats, Ponmudiana gen. nov. is restricted to the hills of Ponmudi and adjoining areas in the southern Western Ghats (cf. Bahir & Yeo 2007; Rajesh et al. 2017; present study), and Travancoriana s. str. is restricted to the Nilgiri Hills in the central Western Ghats (cf. Rathbun 1905; Bott 1969, 1970a, 1970b; Bahir & Yeo 2007; present study), with the prominent Palghat Gap acting as a geographical barrier between the central and southern Western Ghats ( Fig. 1A).

Travancoriana convexa is separated from Travancoriana s. str. and assigned to Palaniana gen. nov. due to the presence of a relatively broader male pleon, with almost straight lateral margins and a trapezoidal, relatively broad pleonal somite 6 with its proximal width ca. 1.5 times the medial length ( Figs. 7C, 9C, E) (versus male pleon relatively narrower, with strongly concave lateral margins and a subquadrate, relatively narrow pleonal somite 6 with its proximal width ca. 1.1 times the medial length; Fig. 2C), and the relatively stout G1, with the ultimate article being relatively stout, straight, long, ca. 0.5–0.6 times the penultimate article ( Figs. 8A, B, 9F, G) (versus G1 relatively slender, with the ultimate article being relatively slender, inwardly curved, short, ca. 0.3–0.4 times the penultimate article; Fig. 3A, B). The geographical range of Palaniana gen. nov. (southern Western Ghats) does not overlap with that of Travancoriana s. str. (central Western Ghats), with the Palghat Gap acting as a barrier in between those isolated mountains (cf. Rathbun 1905; Roux 1931; Bott 1969, 1970a, 1970b; Bahir & Yeo 2007; Pati et al. 2014; Rajesh et al. 2017; present study) ( Fig. 1A).

Travancoriana granulata can be easily distinguished from Travancoriana s. str. by the relatively slender adult male chelipeds (see Pati & Sharma 2013: figs. 2A–C, 3E) (versus adult male chelipeds relatively stouter; Fig. 2A), the male s2/s3 being distinct as narrow groove reaching the edge of the sternum ( Fig. 10D) (versus male s2/s3 being visible as broad groove not reaching the edge of the sternum; Fig. 2C), the relatively shorter male sternopleonal cavity reaching to the imaginary line joining the medial part of the cheliped coxae ( Fig. 10D) (versus male sternopleonal cavity relatively longer reaching to the imaginary line joining the anterior part of the cheliped coxae; Fig. 2C), the relatively broad male pleonal somite 6 with its proximal width ca. 1.5 times the medial length ( Fig. 10D, E) (versus male pleonal somite 6 relatively narrow with its proximal width ca. 1.1 times the medial length; Fig. 2C), and the outwardly curved and relatively shorter G1 ultimate article, ca. 0.25 times the length of the penultimate article ( Fig. 11A, B) (versus G1 ultimate article inwardly curved and relatively longer, ca. 0.3–0.4 times the length of the penultimate article; Fig. 3A, B). Travancoriana granulata is, therefore, assigned in this study to Anamudiana gen. nov. In addition to the morphological differences, Anamudiana gen. nov. is separable from Travancoriana s. str. geographically. This new genus is limited in distribution to the southern Western Ghats further south of the Palghat Gap, whereas Travancoriana s. str. is precisely known only from the central Western Ghats further north of the Palghat Gap (cf. Rathbun 1905; Bott 1969, 1970a, 1970b; Bahir & Yeo 2007; Pati & Sharma 2013; present study) ( Fig. 1A).

Travancoriana kuleera is assigned to a new genus, Naduganiana gen. nov., because it can be separated from Travancoriana s. str. by its medium size (maximum CW 28.0 mm) (versus large size, maximum CW 55.3 mm), the relatively broader male telson with the medial length ca. 1.0 times the proximal width ( Fig. 12D, G) (versus male telson relatively narrower with the medial length ca. 1.2 times the proximal width; Fig. 2C), and the relatively stouter G1 with the distally distinctly outwardly curved ultimate article ( Figs. 12H, I, 13A, B) (versus G1 relatively slenderer with the distally gently inwardly curved ultimate article; Fig. 3A, B). Although both Naduganiana gen. nov. and Travancoriana s. str. are from the central Western Ghats ( Fig. 1A), members of the new genus dwell at relatively lower elevations ( 651–800 m a.s.l.) (cf. Bahir & Yeo 2007; present study), whereas those of Travancoriana s. str. are so far known only from the higher elevations ( 917–1883 m a.s.l.) (cf. Rathbun 1905; Bott 1969, 1970a, 1970b; Bahir & Yeo 2007).

Travancoriana Bott, 1969 , is thus restricted to its type species, i.e., T. schirnerae Bott, 1969 . Among the gecarcinucid genera of southern India, Travancoriana can be recognised mainly by the following suite of morphological characters: large size (maximum CW 55.3 mm); the relatively broad and low carapace (CW/CL = ca. 1.3–1.5; CH /CW = ca. 0.4) ( Fig. 2A, B); the well-developed postorbital cristae reaching lateral margins of carapace ( Fig. 2A); the broadly triangular external orbital angle with a relatively longer outer margin, ca. 4 times the length of the inner margin ( Fig. 2A); the low epibranchial tooth, located at the same level of the postorbital cristae ( Fig. 2A); the well-developed flagellum on the exopod of the maxilliped 3 (see Bahir & Yeo 2007: fig. 7C); a complete male s3/s4 ( Fig. 2C); the relatively narrow male pleon with the subquadrate and relatively narrow pleonal somite 6 ( Fig. 2C); the relatively narrower male telson ( Fig. 2C); the relatively slender G1 with the distally gently inwardly curved and relatively short ultimate article, ca. 0.3–0.4 times length of penultimate article ( Fig. 3A, B); and the equally long G1 and G2 ( Fig. 3A, C).

Geographical distribution. Travancoriana s. str. is precisely known only from the higher elevations ( 917– 1883 m a.s.l.) of the central Western Ghats in the Tamil Nadu state (Nilgiris district) of southern India ( Rathbun 1905; Bott 1969, 1970a, 1970b; Bahir & Yeo 2007) ( Fig. 1A).