Naduganiana kuleera ( Bahir & Yeo, 2007 ), 2025

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 : 26-31

Naduganiana kuleera ( Bahir & Yeo, 2007) comb. nov.

[Nadugani crab]

( Figs. 12, 13)

Travancoriana kuleera Bahir & Yeo, 2007: 323 , figs. 14, 15.

Travancoriana kuleera – Rajesh et al. 2017: 145, fig. 24.—Pati 2020: 162 (list).— Pati & Pradhan 2020: 555836 (list).— Sruthi & Thirunavukkarasu 2022: 460.

Type material examined. Holotype: male ( CW 28.0 mm, CL 19.7 mm) ( ZRC 2003.0240 ), India, Kerala State, Malappuram District , “ between Gudalur and Manjery, Tamil Nadu ” [ between Gudalur and Manjeri], 11.42536° N, 76.37961° E, elev. 800 m a.s.l., collector and collection date unknown.

Other material examined. India– Tamil Nadu State: 3 males ( CW 13.6–19.3 mm, CL 10.4–14.6 mm, CH 5.8–8.5 mm, FW 4.6–6.1 mm), 4 females ( CW 11.4–19.3 mm, CL 8.9–14.5 mm, CH 4.7–8.4 mm, FW 3.8–5.9 mm) ( ZSI-WRC C.2470), Nilgiris District , Nilambur-Nadugani road, 11.438° N, 76.393° E, elev. 651 m a.s.l., coll. B. Tripathy et al., 24 November 2023 .

Diagnosis. As for new genus.

Remarks. The records of the species as Travancoriana kuleera by Pati et al. (2014, 2019b) from the Malabar Wildlife Sanctuary of the Kozhikode district of Kerala are a clear case of misidentification; the species appears like a species of Vanni instead (see Pati et al. 2014: pl. 1 figs. 13–15, pl. 3 figs. 10–12; 2019b: pl. 1 fig. 4).

The type locality of Naduganiana kuleera comb. nov. was stated as “between Gudalur and Manjery, Tamil Nadu ” by Bahir & Yeo (2007). Based on the verbatim geographic coordinates provided by Bahir & Yeo (2007), Pati et al. (2014) confirmed that the holotype and male paratypes were originated from the Malappuram district of Kerala, while the female paratypes were from the Nilgiris district of Tamil Nadu. Some specimens of this species have also been collected from a stream that acts as a political boundary between Kerala and Tamil Nadu (see other material examined). The species is thus distributed in the Nadugani Hills on both sides of these two states.

From the above-mentioned stream, crabs of Barytelphusa cunicularis (Westwood in Sykes, 1836) were also collected along with Na. kuleera comb. nov. (see ecological notes below). The subadult crabs (CW < 44 mm) of B. cunicularis superficially resemble the adult crabs of Na. kuleera comb. nov. The male adults/subadults of B. cunicularis can be easily recognised from the male crabs of Na. kuleera comb. nov. (see remarks for Naduganiana gen. nov. on the differences among the new genus and other gecarcinucid genera of southern India). The female subadults of B. cunicularis , however, are likely to be confused with the females of Na. kuleera comb. nov., especially due to the presence of a more or less equally long outer margin of the external orbital angle ( Fig. 12A, E; see Pati & Yeo 2022: fig. 1A). In such cases, the females of Na. kuleera comb. nov. can be differentiated from the subadult females of B. cunicularis by the following non-sexual characteristics: the epibranchial tooth is very low, almost indiscernible, and inseparable from the postorbital crista by the cervical groove ( Fig. 12A, E) (versus epibranchial tooth low but distinct, and separated from the postorbital crista by the deep cervical groove; see Pati & Yeo 2022: fig. 1A); and the epistome posterior margin possesses a trapezoidal medial tooth, and the strongly sinuous lateral lobes ( Fig. 12C) (versus epistome posterior margin possessing a triangular medial tooth, and the concave lateral lobes with the outer parts sloping downwards; see Pati & Yeo 2022: fig. 1B).

Ecological notes. Naduganiana kuleera comb. nov. was reported by Bahir & Yeo (2007) to occur underneath small stones of a very shallow stream in a well-shaded area. The present specimens from the same general area were collected from under small stones and boulders of a stream in an open area. Two other gecarcinucid species, Barytelphusa cunicularis and Vela carli ( Roux, 1931) , were also found to inhabit the same and nearby streams.

Geographical distribution. As for new genus.

Genus Vanni Bahir & Yeo, 2007

( Figs. 14–21)

Vanni Bahir & Yeo, 2007: 336 .

Vanni – Klaus et al. 2014: 654 (list).— Rajesh et al. 2017: 134 (list).— Pati et al. 2019c: e2019006 (list).—Pati 2020: 162 (list).— Pati & Pradhan 2020: 555836 (list).— Sruthi & Thirunavukkarasu 2022: 460 (list).

Type species. Paratelphusa ( Liotelphusa) malabarica var. travancorica Henderson, 1913 , by original designation; gender of genus feminine.

Diagnosis. Medium sized crabs (maximum CW 27.4 mm). Carapace relatively broad (CW/CL = ca. 1.2–1.4), relatively low ( CH /CW = ca. 0.4–0.5), with moderately convex lateral margins; frontal medial triangle incomplete, lateral margins indiscernible; postorbital cristae well-developed, reaching lateral margins of carapace; external orbital angle triangular, with short outer margin, ca. 2–2.5 times length of inner margin; epibranchial tooth indiscernible or low, located at same level of postorbital cristae; epistome posterior margin with well-developed, triangular medial tooth and gently sinuous lateral lobes ( Figs. 14A, B, 16A, B, 18A–C, E, 20A–C, E). Maxilliped 3 with well-developed flagellum on exopod ( Figs. 14D, 16E, 18F, 20F). Chelipeds relatively slender in adult males ( Figs. 14A, 16A, C, F, 18A, E, 20A, E). Ambulatory legs relatively stout, shorter, setose ( Figs. 14A, 16A, C, 18A, E, 20A, E). Male s2/s3 visible as groove, not reaching edge of sternum; male s3/s4 indiscernible ( Figs. 14C, 16C, G, 18D, 20D). Male sternopleonal cavity relatively short, reaching to imaginary line joining anterior part of cheliped coxae ( Figs. 14C, 16C, G, 18D, 20D). Male pleon relatively narrow, with strongly concave lateral margins; pleonal somite 6 subquadrate, relatively narrow, proximal width ca. 1.1–1.2 times medial length ( Figs. 14C, E, 16C, H, 18D, G, 20D, G). G1 relatively slender; ultimate article conical, relatively slender, relatively short, ca. 0.2–0.3 times length of penultimate article; penultimate article slender to moderately stout ( Figs. 15A, B, 17A, B, 18H, I, 19A, B, 20H, I, 21A, B). G2 longer than G1, ca. 1.1–1.2 times G1 length; ultimate article long, ca. 0.4 times length of penultimate article ( Figs. 15C, 17C, 18J, 19C, 20J, 21C). Vulvae relatively widely located from each other (VD/SW = ca. 0.2) ( Figs. 14F, 16J, 18K, 20K).

Remarks. Vanni was recognised as a new genus by Bahir & Yeo (2007), who included seven species: V. ashini Bahir & Yeo, 2007 ; V. deepta Bahir & Yeo, 2007 ; V. giri Bahir & Yeo, 2007 ; V. malabarica ( Henderson, 1912) ; V. nilgiriensis ( Roux, 1931) ; V. pusilla ( Roux, 1931) ; and V. travancorica ( Henderson, 1913) (the type species). Vanni , however, is a polyphyletic genus, with V. nilgiriensis and V. malabarica forming separate clades from the clade comprising V. travancorica and V. deepta in the phylogenetic tree of Klaus et al. (2014: fig. 1). Morphologically, V. nilgiriensis and V. malabarica are also so distinct from Vanni s. str. (which includes the type species V. travancorica , as well as V. ashini , V. deepta , and a new species, V. gracilis sp. nov.) that each of these species requires new generic names as do V. giri and V. pusilla . The key identifying characters used by Bahir & Yeo (2007) to distinguish Vanni s. lat. from the other genera of southern India require amendment, especially since the genus is now known to be polyphyletic ( Klaus et al. 2014).

According to the identification key to the southern Indian freshwater crab genera provided by Bahir & Yeo (2007), Vanni possesses a set of key characters that includes a relatively squarish carapace, usually less strongly developed postorbital cristae, a less broad external orbital angle with a short outer margin (ca. 1.5–2 times the inner margin), and a proportionately shorter G1 ultimate article (ca. 0.2–0.3 times the penultimate article), which differentiates it from Travancoriana that has a distinctly transverse carapace, usually strongly developed postorbital cristae, a distinctly broader external orbital angle with a long outer margin (ca. 3–5 times the inner margin), and a proportionately longer G1 ultimate article (ca. 0.3–0.6 times the penultimate article). This set of key characters does not apply to all species of Vanni s. lat. For instance, the carapace is slightly to distinctly broad (CW/CL = ca. 1.2–1.4) in Vanni s. lat. ( Figs. 14A, 18A, B, E, 20A, B, E, 22A, B, E, F, 23A; see Bahir & Yeo 2007: figs. 32A, 34A, 36A, 38A, 40A, 42A, 44A), which is comparable to that of Travancoriana s. lat. (CW/CL = ca. 1.2–1.4) ( Figs. 2A, 4A, B, E, F, 6A, 7A, 9A, 10A, 12A, B, E). The postorbital cristae are usually less strongly developed only in V. malabarica , V. nilgiriensis , and V. pusilla ( Figs. 22A, B, E, F, 23A; see Bahir & Yeo 2007: figs. 34A, 36A, 38A). The external orbital angle is broadly triangular with a long outer margin (ca. 3.5–5 times the inner margin) in V. pusilla , V. nilgiriensis , and V. giri ( Figs. 22A, B, E, F, 23A; see Bahir & Yeo 2007: figs. 36A, 38A, 44A). The ratios between the ultimate and penultimate articles of the G 1 in the species of Vanni s. lat. (0.2–0.4) ( Figs. 15A, 17A, 18H, 19A, 20H, 21A, 24A; see Bahir & Yeo 2007: figs. 35C, 37D, 43A) overlap with those of Travancoriana s. lat. (0.25–0.4) ( Figs. 3A, 5A, D, 6F, 11A, 12H, 13A) except for Travancoriana convexa ( Figs. 8A, 9F).

Vanni s. str. is thus redefined by the following combination of characters, which separates it from all other gecarcinucid genera of southern India: the carapace is relatively low ( Figs. 14B, 16B, 18C, 20C); the postorbital cristae are well-developed, each reaching the lateral margins of the carapace ( Figs. 14A, 16A, 18A, B, E, 20A, B, E); the external orbital angle is triangular, with a short outer margin, ca. 2–2.5 times the length of the inner margin ( Figs. 14A, 16A, 18A, B, E, 20A, B, E); the epibranchial tooth is indiscernible or low ( Figs. 14A, 16A, 18A, B, E, 20A, B, E); the maxilliped 3 possesses a distinct flagellum on the exopod ( Figs. 14D, 16E, 18F, 20F); the ambulatory legs are relatively stout, shorter, setose ( Figs. 14A, 16A, C, 18A, E, 20A, E); the male s2/s3 is discernible as groove, while the male s3/s4 is indiscernible ( Figs. 14C, 16C, G, 18D, 20D); the male sternopleonal cavity is relatively short, reaching to the imaginary line joining the anterior part of the cheliped coxae ( Figs. 14C, 16C, G, 18D, 20D); the G2 is longer than G1 ( Figs. 15, 17, 18H–J, 19, 20H–J, 21); and the vulvae are relatively widely located from each other (VD/SW = ca. 0.2) ( Figs. 14F, 16J, 18K, 20K).

Vanni s. str. currently includes four species: V. ashini Bahir & Yeo, 2007 ; V. deepta Bahir & Yeo, 2007 ; V. gracilis sp. nov.; and V. travancorica ( Henderson, 1913) ( type species). The generic status of the remaining four species of Vanni s. lat. ( V. malabarica , V. pusilla , V. nilgiriensis , and V. giri ) is discussed below.

Vanni malabarica is morphologically most closely related but distinct from Vanni s. str. because of the posterolaterally weakly developed postorbital cristae, which do not reach the lateral margins of the carapace ( Figs. 22A, B, E, F, 23A) (versus postorbital cristae well-developed reaching the lateral margins; Figs. 14A, 16A, 18A, B, E, 20A, B, E); the low, broadly triangular medial tooth of the epistome posterior margin ( Fig. 22C, G) (versus epistome posterior margin with a well-developed, triangular medial tooth; Figs. 14A, 16A, 18A, B, E, 20A, B, E); the indiscernible male s2/s3 ( Fig. 22D, H) (versus male s2/s3 visible as groove; Figs. 14C, 16C, G, 18D, 20D); the relatively long male sternopleonal cavity, which reaches up to the imaginary line joining the bases of the maxilliped 3 ( Fig. 22D, H) (versus male sternopleonal cavity relatively short, reaching to the imaginary line joining the anterior part of the cheliped coxae; Figs. 14C, 16C, G, 18D, 20D); and the relatively short G2 ultimate article, ca. 0.3 times the length of the penultimate article ( Fig. 24C) (versus G2 ultimate article relatively long, ca. 0.4 times the length of the penultimate article; Figs. 15C, 17C, 18J, 19C, 20J, 21C). In fact, V. malabarica formed a distinct clade from Vanni s. str. in the phylogenetic tree of Klaus et al. (2014: fig. 1). Vanni malabarica is, therefore, assigned to a new genus, Santanusus gen. nov., which is hereby described. Moreover, Vanni s. str. is widely distributed in the central Western Ghats (as far north as Uttara Kannada district of Karnataka) and southern Western Ghats (as far south as Kanyakumari district of Tamil Nadu), at both lower and higher elevations ( 46–1235 m a.s.l.) (cf. Bahir & Yeo 2007; Pati & Sharma 2011, 2014; Pati et al. 2014, 2019b; Rajesh et al. 2017; Pati & Sureshan 2022; present study) ( Fig. 1B). The new genus, Santanusus gen. nov., is also found in the central and southern Western Ghats but restricted only to northern and central Kerala and the Coimbatore district of Tamil Nadu (cf. Henderson 1912; Roux 1931; Bott 1970a, 1970b; Bahir & Yeo 2007; Klaus et al. 2014; Pati et al. 2014, 2019b; Rajesh et al. 2017; present study) ( Fig. 1B).

Vanni pusilla is placed in its own new genus, Pusillosa gen. nov., since it can be differentiated from Vanni s. str. by its small size (maximum CW 12.9 mm) (in contrast to medium sized crabs, maximum CW 27.4 mm) and the following morphological features: the weakly developed postorbital cristae ( Fig. 25A, B; see Bahir & Yeo 2007: figs. 37A, 38A) (versus postorbital cristae well-developed; Figs. 14A, 16A, 18A, B, E, 20A, B, E); the broadly triangular external orbital angle, with a long outer margin, ca. 4 times the length of the inner margin ( Fig. 25A, B; see Bahir & Yeo 2007: figs. 37A, 38A) (versus external orbital angle triangular, with a short outer margin, ca. 2–2.5 times the length of the inner margin; Figs. 14A, 16A, 18A, B, E, 20A, B, E); the relatively slenderer and longer ambulatory legs ( Fig. 25A, H; see Roux 1931: fig. 16) (versus ambulatory legs relatively stouter and shorter; Figs. 14A, 16A, C, 18A, E, 20A, E); the indiscernible male s2/s3 ( Fig. 25D; see Bahir & Yeo 2007: figs. 37B, 38C) (versus male s2/s3 visible as groove; Figs. 14C, 16C, G, 18D, 20D); the relatively broader male pleon, with the trapezoidal and conspicuously broad pleonal somite 6, proximal width ca. 1.5 times the medial length ( Fig. 25D, I; see Bahir & Yeo 2007: figs. 37C, 38C) (versus male pleon relatively narrower, with the subquadrate and conspicuously narrow pleonal somite 6, proximal width ca. 1.1–1.2 times the medial length; Figs. 14C, E, 16C, H, 18D, G, 20D, G); and the relatively stouter G1, with a stout penultimate article ( Fig. 26A, B; see Bahir & Yeo 2007: fig. 37D, E) (versus G1 relatively slenderer, with slender to moderately stout penultimate article; Figs. 15A, B, 17A, B, 18H, I, 19A, B, 20H, I, 21A, B). Pusillosa gen. nov. is endemic to the central Western Ghats and restricted to the higher elevations ( 2100–2315 m a.s.l.) of the Nilgiris district in Tamil Nadu (cf. Roux 1931; Bott 1970a, 1970b; Bahir & Yeo 2007; present study) ( Fig. 1B), whereas Vanni s. str. is a widely distributed genus in both the central and southern Western Ghats, occurring at lower as well as higher elevations (cf. Bahir & Yeo 2007; Pati & Sharma 2011, 2014; Pati et al. 2014, 2019b; Rajesh et al. 2017; Pati & Sureshan 2022; present study) ( Fig. 1B).

Vanni nilgiriensis and a new species, with affinities to it, are transferred to a new genus, Nilgiriana gen. nov., with the following morphological characters separating them from Vanni s. str.: the weakly developed postorbital cristae ( Figs. 27A, B, E, F, 30A) (versus postorbital cristae well-developed; Figs. 14A, 16A, 18A, B, E, 20A, B, E); the broadly triangular external orbital angle, with a long outer margin, ca. 4–5 times the length of the inner margin ( Figs. 27A, B, E, F, 30A) (versus external orbital angle triangular, with a short outer margin, ca. 2–2.5 times the length of the inner margin; Figs. 14A, 16A, 18A, B, E, 20A, B, E); the glabrous ambulatory legs ( Fig. 27A, E) (versus ambulatory legs setose; Figs. 14A, 16A, C, 18A, E, 20A, E); the trapezoidal and relatively broader male pleonal somite 6, proximal width ca. 1.3–1.9 times the medial length ( Figs. 27D, H, 29D) (versus male pleonal somite 6 subquadrate and relatively narrower, proximal width ca. 1.1–1.2 times the medial length; Figs. 14C, E, 16C, H, 18D, G, 20D, G); and the subconical, inverted funnel-shaped, distally suddenly tapered ultimate article of the G1 ( Figs. 28A, B, D, E, 29E, G) (versus G1 ultimate article conical, gradually tapered distally; Figs. 15A, B, 17A, B, 18H, I, 19A, B, 20H, I, 21A, B). Nilgiriana gen. nov. is currently known only from the central Western Ghats of Karnataka, Kerala, and Tamil Nadu (cf. Roux 1931; Bott 1970a, 1970b; Bahir & Yeo 2007; Pati et al. 2019c; present study) ( Fig. 1B), while Vanni s. str. is widely distributed in both the central and southern Western Ghats (cf. Bahir & Yeo 2007; Pati & Sharma 2011, 2014; Pati et al. 2014, 2019b; Rajesh et al. 2017; Pati & Sureshan 2022; present study) ( Fig. 1B).

Vanni giri is also placed in the present study in Idukkiana gen. nov., as the species possesses the following characters differing from Vanni s. str.: the broadly triangular external orbital angle, with a long outer margin, ca. 3.5 times the length of the inner margin ( Fig. 31A) (versus external orbital angle triangular, with a short outer margin, ca. 2–2.5 times the length of the inner margin; Figs. 14A, 16A, 18A, B, E, 20A, B, E); the male s3/s4 visible as the shallow, complete groove, reaching the sternum edge ( Fig. 31C) (versus male s3/s4 indiscernible; Figs. 14C, 16C, G, 18D, 20D); and the straight lateral margins of the male pleonal somite 6 ( Fig. 31C) (versus male pleonal somite 6 with gently to strongly concave lateral margins; Figs. 14C, E, 16C, H, 18D, G, 20D, G). Idukkiana gen. nov. is a high mountain dweller (elevation of 1570 m a.s.l.) and is currently restricted only to the Idukki district of Kerala in the southern Western Ghats (cf. Bahir & Yeo 2007) ( Fig. 1B). In contrast, Vanni s. str. has a wider distribution, occurring at both lower and higher elevations of the central and southern Western Ghats (cf. Bahir & Yeo 2007; Pati & Sharma 2011, 2014; Pati et al. 2014, 2019b; Rajesh et al. 2017; Pati & Sureshan 2022; present study) ( Fig. 1B).

Geographical distribution. Vanni s. str. is certainly known from both lower and higher elevations ( 46–1235 m a.s.l.) of the southern Western Ghats in Kerala (Ernakulam, Idukki, Kollam, Pathanamthitta, and Thiruvananthapuram districts) and Tamil Nadu (Kanyakumari and Tirunelveli districts), southern India ( Bahir & Yeo 2007; Rajesh et al. 2017; Pati & Sureshan 2022; present study) ( Fig. 1B). Vanni s. str. is also known from the central Western Ghats of Kerala (including Kozhikode, Palakkad, and Wayanad districts) and Karnataka (as far north as Uttara Kannada district) (cf. Pati & Sharma 2011, 2014; Pati et al. 2014, 2019b) ( Fig. 1B).