Raorchestes asakgrensis Naveen, Chandramouli & Babu, 2024

Naveen, R. S., Chandramouli, S. R., Babu, S., Ryndongsngi, A. M., Karunakaran, P. V. & Kumara, Honnavalli N., 2024, Rediscovery and redescription of Ixalus garo Boulenger, 1919, and Ixalus kempiae Boulenger, 1919, with a reassessment of the taxonomic status of Raorchestes cangyuanensis Wu, Suwannapoom, Xu, Murphy & Che, 2019 and the description of a new species from the Garo Hills of Meghalaya, Herpetozoa 37, pp. 359-372 : 359-372

Raorchestes asakgrensis Naveen, Chandramouli & Babu sp. nov.

Material studied.

Holotype: An adult female, SACON VA 805 (Fig. 6 ) from Eman Asakgre Community Reserve (25.36788 ° N, 90.54344 ° E, 174 m), Meghalaya, India, collected by RSN on August 15 th, 2023.

Paratypes: Three adult males, SACON VA 339 , 340, and VA 343 , from Eman Asakgre Community Reserve (25.36788 ° N, 90.54344 ° E, 174 m), Meghalaya, India, collected by RSN on August 15 th, 2023 .

Diagnosis.

Raorchestes asakgrensis sp. nov. is placed in the genus Raorchestes due to the combination of the following characters: small body size, vomerine teeth absent, single translucent external subgular vocal sac present, and tips of all fingers and toes expanded into discs with circum-marginal grooves (see Biju et al. 2010). The species can be distinguished from congeners in the Indo-China region by the following combination of characters: A small-sized (mean SVL 20.49 mm) arboreal species with an obtusely pointed snout; tympanum fairly visible with a visible supra-tympanic, relatively weakly developed; vomerine teeth absent; single semi-transparent gular vocal sac; tongue without papilla; ventral aspect of the hind limb uniform white as the venter; finger and toe discs well developed; toe webbing I 1-2 II 2 - 2 III 2 - 1 IV 1 - 2 V. Phylogenetically, R. asakgrensis forms a well-supported clade ( BS: 100) consisting of two more Genbank sequences from ‘ India’ ( JX 092712.1 ) and Nongkhyllem, Meghalaya ( MN 524578.1 ).

Description of the holotype.

A small-sized Raorchestes (SVL 22.8 mm), dorsal and lateral skin smooth, venter granulated. Head wider than long (HL: HW 0.82); large (HL: SVL 0.28). A short snout (ED: ES 0.9), obtusely pointed in dorsal view. Canthus rostralis evident and rounded; loreal region concave. Trunk short (AG: SVL 0.43) and less gracile (AG: BW 0.95); eyes large (ED: HL 0.42); nostrils rounded, situated closer to the snout tip than to the eyes (EN: ES 0.53), directed laterally with no visible rim. Tympanum fairly visible, rounded in shape (TYD 1.92 mm); Supra-tympanic fold relatively weakly developed; Inter-orbital space broader than inter-narial space (IO: IN 1.14). Upper arms short (UAL: SVL 0.18), shorter than lower arms (UAL: LAL 0.79); palm shorter than the upper arms (UAL: PAL 0.75); relative finger lengths III> IV> II> I. Subarticular tubercles distinct in both palmar and plantar surfaces, rounded; Supernumerary tubercles present in the palm; no webbing between fingers; fingers with well-developed rounded discs. Thighs short, nearly half as long as the body (FEL: SVL 0.48), slightly shorter than the tibia (FEL: TBL 0.89). Foot slightly shorter than the thigh (FEL: FOL 1.12), toes, short with well-developed rounded discs and partial webbing, webbing formula I 1-2 II 2 - 2 III 2 - 1 IV 1 - 2 V. In life dorsum uniformly brown with a faint “) - (“ mark; loreal yellowish brown; iris golden brown. Venter uniformly white, pale white eggs visible through ventral surface. Forearm and hindlimbs with dark brown bands (Fig. 7 ).

Variation.

Measurement of the paratypes presented in Table 4 . Variations noted during examination of preserved specimens and live individuals observed in the field. The single known female (Holotype VA 805) is larger (SVL 22.8 mm) than all the male specimens examined during this study (range 18.68–21.5 mm; mean SVL 19.72 mm). One of the male paratypes (VA 340) with a thin yellow line passing dorsally from the tip of the snout to the cloaca and extending through the thighs and shank (Fig. 7 ). Dorsal coloration pale to dark brown with or without a faint or dark hourglass pattern, “) (“.

Comparisons.

Raorchestes asakgrensis sp. nov. is genetically divergent (5.8–10.8 %) from congeners, with the closest species being R. shillongensis with a divergence of 5.8 %. On the phylogenetic tree, it clusters with a clade comprising R. garo and R. shillongensis , with a moderate node support (79). From species occurring in the Indo-China region, it can be distinguished by: having an obtusely pointed snout (vs. truncate and scarcely projecting in R. garo , rounded in R. kempiae , R. menglaensis , R. hillisi , R. hekouensis , R. malipoensis , R. longchuanensis , R. dulongensis , and R. huanglianshan and sharply projecting in R. annandalii and R. yadongensis ), a fairly visible tympanum (vs. not externally visible in R. kempiae , R. shillongensis , R. rezakhani , R. menglaensis , and R. parvulus ); and the presence of supernumerary tubercles on the palmar surface (vs. absent in R. dulongensis , R. yadongensis , and R. hekouensis ). Ventral aspect of the hind limb uniformly creamy white in color (vs. dark orange in R. garo and R. annandalii , yellow with brown to black blotches in R. kempiae , and pale brown with white flecks in R. parvulus ); toe webbing formula I 1-2 II 2-2 III 2-1 IV 1-2 V (vs. I 1-1 II 1-1 III 3-3 IV 3-2.5 V in R. garo , I 1-2 II 2 - 1 III 1 - 1 IV 1 - 2 V in R. kempiae , I 2–2 II 2–2 III 2–3 IV 3–2 V in R. malipoensis , II 1–2 III 1–2.5 IV 2.5–1 V in R. menglaensis , II 1–2 III 1–2.5 IV 2.5–1 V in R. hillisi , II 1–2 III 1–2 – IV 2–1 V in R. huanglianshan , I 2‒2 II 1.5 ‒ 3.25 III 2 ‒ 3.5 IV 3.25 ‒ 2 V in R. parvulus and I 2–2 II 1.75–2 III 1.5–3 IV 2.75–2 V in R. rezakhani ).

Remarks.

The new species is clearly differentiated by a distinct set of morphological characters, particularly the presence of an externally visible tympanum and snout shape (see Fig. 7 ). Boruah et al. (2018) reported a Raorchestes sp. from regions north of the Khasi Hills, and it is likely that this could be R. asakgrenesis , as we also recorded this species from near Nongkhyllem Wildlife Sanctuary.

Natural history and distribution.

The frogs were seen calling at dusk from bushes in and around the Eman Asakgre Community Reserve. A single amplecting pair was recorded at around 19: 30 h perched on a bush 1.5 m above the ground during the pre-monsoon season following the first shower in May. The sequence generated during the current study also matches closely with a sequence from Nongkhyllem ( MN 524577.1 ), foothills of Khasi hills (about 150 km away from the type locality) in Meghalaya. In addition to this, during this study this species was also recorded from various locations across Garo hills (Sasatgre, Oragitok, and Dangkipara) and low-elevation regions of Khasi hills (Umling and Nongpoh). We calculated the extent of occurrence of this species with the current data from this study, and it was estimated to be 1,625 km 2 across an elevational range of 150 m asl to 950 m asl; however, further surveys are required to robustly estimate the distribution range of this species.

Etymology.

The species is named after the type locality, Eman Asakgre Community Reserve, to honor the residents who greatly supported the surveys during which the type specimens were collected.

Figures

Figure 6. Adult female holotype (SACON VA 805) and adult male paratype (SACON VA 343) of Raorchestes asakgrensis sp. nov. in preservative, A. dorsal; C. ventral of holotype, and B. dorsal; D. ventral of paratype. Scale bars: 10 mm.

Figure 7. Raorchestes asakgrensis sp. nov. holotype, SACON VA 805, an adult female dorso-lateral view in life (above); paratype, SACON VA 340, an adult male dorso-lateral view in life (below).