Raorchestes cinerascens ( Stoliczka, 1870 ), 2025

Boruah, Bitupan, Deepak, V. & Das, Abhijit, 2025, Revision of bush frogs, Raorchestes and Philautus (Amphibia: Anura: Rhacophoridae) from the northeast Indian biodiversity hotspot with description of thirteen new species, Vertebrate Zoology 75, pp. 517-625 : 517-625

Raorchestes cinerascens ( Stoliczka, 1870) nov. comb.

Chresonymy.

Ixalus cinerascens Stoliczka, 1870: 275 .

Ixalus cinerascens — Sclater (1892 a): 347; Sclater (1892 b): 20; Annandale (1908): 305.

Rhacophorus ( Philautus) cinerascens — Ahl (1931): 75.

Philautus cinerascens — Broadley (1971): 112; Chanda et al. (2000): 112; Zug (2022): 42.

Philautus ( Philautus) cinerascens — Bossuyt and Dubois (2001): 23.

Comments on taxonomic status.

Philautus cinerascens (Fig. 14 ) was described by Stoliczka (1870) based on specimens collected by W. Theobald from “ Atran River, east of Moulmein ( Tanintharyi Division) ”, Myanmar. Annandale (1913) mentioned the type locality as “ probably the Dawna Hills inland from Moulmein ”. Since its description, there is no further report of this species from the type locality. The original voucher numbers for the specimens were not mentioned in Stoliczka (1870). Stoliczka (1872) mentioned that this species was described based on two specimens from Moulmein. However, Chanda et al. (2000) mentioned that there are four syntypes under the number “ ZSIC 2716 ”. Although this species was described based on multiple specimens ( Bossuyt and Dubois 2001), only a single type specimen is mentioned in the literature (e. g., Anderson 1871; Sclater 1892 a, 1892 b; Annandale 1908, 1913). Sclater (1892 b) gave the voucher number “2716” and called it the “ type of the species ”. We found four specimens (Fig. 14 ) with the same voucher number “ ZSI 2716 ” at ZSI, Kolkata. As these specimens are in a bad state of preservation, only a few characters could be examined. Among the four specimens, the largest specimen ( SVL 16 mm) can be assigned to the genus Raorchestes based on the following morphological characters and geographical distribution of Philautus sensu stricto: 1) vomerine teeth absent, 2) absence of serrated dermal fringe along forearms and tarsus, 3) absence of light coloured dorsolateral stripes along the dorsum, 4) absence of calcar. The original description corresponds to this specimen, where Stoliczka (1870) mentioned the size of this specimen as “ ¾ of an inch ” and as the largest of the specimens. Sclater (1892 a) and Annandale (1913) also mentioned this specimen as “ a true Ixalus ”. However, the other three specimens differ from the “ type ” and no doubt belong to one or more rhacophorid genera but not Raorchestes or Philautus . These three specimens have smooth skin on the dorsal surface of the head, dorsum, and limbs; abdominal skin indistinctly granular; thigh ventrally smooth. Most importantly, these three specimens have much longer hind limbs. One which we measured (Fig. 14 G, H ) has a femur length 60 % of the SVL ( 13.9 mm) and a tibia length of 62 % of SVL. At this stage it is not possible to assign these three specimens to any genus due to the condition of the specimens. We propose to consider the largest type specimen ( ZSI 2716 ) as Raorchestes (Fig. 14 E, F ) which corresponds to the original description, and because Sclater (1892 a) and Annandale (1913) referred to this specimen as the type for the nomen and as a “ true Ixalus ”. Thus, based on the above-mentioned morphological characteristics, we transfer Philautus cinerascens to Raorchestes cinerascens nov. comb. Consequently, we designate this specimen as the lectotype for Raorchestes cinerascens nov. comb. However, the status of the other three specimens will remain pending. To stabilize the taxonomy of this specimen and the other three syntypes, a redescription based on the newly collected material from the type locality is necessary.

Description of lectotype.

Small sized Raorchestes, SVL 16 mm (Fig. 14 E, F ); lower jaw broken anteriorly; both the forelimbs broken at elbow; left hind limb broken at groin and tibiotarsal articulation; right hindlimb broken at knee and toes completely damaged; longitudinal incision on belly. Snout rounded in dorsal and ventral aspect; canthus rostralis indistinct; vomerine ridge or teeth absent; tympanum indistinct; supratympanic fold distinct; finger disc rounded, circummarginal groove present; thigh length slight greater than tibia length ( TBL / TL = 0.98); toe disc rounded, with circummarginal groove; skin on dorsal aspect of head, dorsum and limbs smooth; a few indistinct tubercles on upper eyelids and posterior part of head behind upper eyelids; on ventral aspect, gular region and chest smooth; belly and thigh granular; tibia smooth on ventral aspect.

Colouration in preservative.

Dorsal aspect of head, dorsum and limbs brown, slightly paler towards flank and base of the hindlimb; ventral aspect nearly uniform brown but slightly paler than the dorsal colour. Except slightly dark patch on groin and slightly dark and single broad cross bar on thigh and tibia, other colour pattern such as dark bar on inter-upper eyelids space, stripes on dorsum; bands on forearms, silvery tinge encircling dark patch on groin as mentioned in the original description are not visible now.

Figures

Figure 14. Previous syntypes of Raorchestes cinerascens nov. comb. under the voucher number ZSI 2716. (A) Lectotype, the largest specimen of the three is shown in the inset image and E dorsal view, and F ventral view; the second largest specimen (D) is shown in the inset and G dorsal view, H ventral view. Scale bar = 10 mm.