Nasutixalus jerdonii ( Günther, 1876 )

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

Nasutixalus jerdonii ( Günther, 1876)

Figures 7 , 8; Tables S 10, S 11

Synonymy and chresonymy.

Polypedates jerdonii Günther, 1876: 571 .

Rhacophorus jerdonii — Boulenger (1882): 80; Das and Dutta (1998): 67.

Rhacophorus ( Rhacophorus) jerdonii — Ahl (1931): 114; Dutta (1997): 101.

Rhacophorus ( Rhacophorus) buergeri jerdonii — Wolf (1936): 172.

Philautus ( Kirtixalus) jerdonii — Dubois (1987): 73.

Philautus ( Philautus) jerdonii — Bossuyt and Dubois (2001): 25.

Philautus sahai Sarkar & Ray, 2006: 303 .

Pseudophilautus sahai — Li et al. (2009): 519.

Philautus sahai — Ahmed et al. (2009): 16.

Raorchestes sahai — Biju et al. (2010): 1120.

Frankixalus jerdonii — Biju et al. (2016): 6 –13.

Nasutixalus jerdonii — Sivongxay et al. (2016): 439–440.

Comments on taxonomic status.

Raorchestes sahai (Fig. 7 ) was originally described as Philautus sahai by Sarkar and Ray (2006) based on two specimens collected by S. S. Saha on 29 February 1988 from 10 km north of Gandhigram, Changlang District, Arunachal Pradesh, India. After Biju et al. (2010), this species was placed under Raorchestes by implication ( Frost 2025). Since its description, this species has not been reported from the type locality and no attempt has been made to study the types or compare them with other species in Raorchestes or other genera of small rhacophorids. We examined the type series ( ZSIA 8500 and ZSIA 8501 ) available at the Zoological Survey of India, Kolkata. Our examination of the types revealed some characteristics that contradict the original description of the species by Sarkar and Ray (2006), such as vomerine teeth present in both types although underdeveloped (vs. vomerine teeth absent in original description) (Fig. 7 ); snout truncated in dorsal and lateral view, rounded in ventral view (vs. snout rounded in original description); rudimentary webbing present on hand (vs. not mentioned in original description). Thus, presence of vomerine teeth in the type specimens suggest that this species does not belong to the nominal genus Raorchestes . Between the years 2022 and 2023, we collected three rhacophorid specimens from Gandhigram that morphologically correspond to the type specimens of R. sahai based on the following set of characters such as truncated snout, protruding eyes, vomerine teeth present, tympanum distinct, rudimentary webbing present on hand, webbing well developed on foot, disc on fingers and toes, abdomen and thigh granular (Figs 7 and 8 ).

Furthermore, in our phylogenetic analysis ( ML) based on the 16 S mitochondrial gene, the newly collected samples (of both subadult and adult) formed a clade with Nasutixalus jerdonii ( Günther, 1876) from northeast India (Fig. 8 A ). The uncorrected p distance between the newly collected samples and available sequences of N. jerdonii from India included in this study are 0.0–0.2 % in the 16 S gene (Table S 10).

We also examined the type specimens of N. jerdonii at the Natural History Museum, London collection ( BMNH 1947.2.7.84 and BMNH 1947.2.7.85 ). Our topotypes agreed with the N. jerdonii types based on the following set of morphological characters: 1) snout rounded or almost truncate in dorsal view and nearly vertical in lateral view; 2) tympanum distinct; 3) small webbing present on hand; 4) circum-marginal groove present on finger and toe disc; 5) toe webbing moderate; 6) granular belly and ventral aspect of thigh; 7) dark patch covering posterior part of head on dorsal aspect, continuing to dorsum and posteriorly bifurcate. The following exceptions or variations were observed in the newly collected material and previously published descriptions. Biju et al. (2016) mentioned that vomerine ridges present in two oblique series without teeth. However, the original description mentioned that vomerine teeth are present. Based on our specimens collected from different parts of northeast India ( Meghalaya, Mizoram, and Arunachal Pradesh), most of the specimens of N. jerdonii have blunt vomerine teeth on two oblique series. In some other specimens (for example WII-ADA 3240 ) which is genetically similar, vomerine ridge is present without teeth. Additionally, Jiang et al. (2016) mentioned that vomerine teeth are present in N. medogensis Jiang, Wang, Yan & Che, 2016 , while Yang and Chan (2018) mentioned vomerine ridge present without teeth in N. yingjiangensis Yang & Chan, 2018 . Thus, this character is not consistent within the genus and species. Biju et al. (2016) mentioned that metacarpal tubercles are absent. However, metacarpal tubercles are visible in the types as well as in our newly collected specimens. Based on the morphological similarity of the topotypes to the holotype and paratype and the phylogenetically close position of the topotypes to N. jerdonii , we consider “ R. sahai ” to be a junior subjective synonym of N. jerdonii . However, none of the available DNA sequences of N. jerdonii by Biju et al. (2016) and Muansanga et al. (2022) are from the type locality in Darjeeling. Those available sequences are from the hill ranges of the southern slope of the Brahmaputra Valley. Therefore, topotypic samples are needed to determine whether N. jerdonii sensu stricto from Darjeeling and the populations from south of Brahmaputra Valley currently referred to as N. jerdonii belong to the same species or represent different species.

Sarkar and Ray (2006) placed this species in the genus Philautus probably because of the small body size of the collected material. Although Sarkar and Ray (2006) referred to the type series as adults, we confirmed that the types are subadults based on the newly collected subadult and adult specimens from the type locality at Gandhigram. Additionally, this species was never compared with N. jerdonii in the past probably because both the species were placed in different genera. For taxonomic stability, we provide here an expanded description of N. jerdonii based on the newly collected material from the type locality of “ R. sahai ”.

Materials examined.

A subadult female ( WII-ADA 1770 ) and an adult male ( WII-ADA 1773 ) collected by BB, AD and NGP on 16 September 2022 at Gandhigram ( 27.265139°N, 96.937041°E, elevation 1120 m a. s. l.), Changlang District, Arunachal Pradesh ; an adult male ( WII-ADA 3240 ) collected from same locality by AD, SD, RNV and JDG on 23 May 2023 .

Description of newly collected male specimen ( WII-ADA 1773 ; Fig. 8 B – H).

Medium sized rhacophorid frog, SVL 41 mm; head slightly wider than long ( HW / HL = 0.98); snout rounded in dorsal and semicircular in ventral view, vertical in lateral view; snout length smaller than eye length ( SL / EL = 0.9); canthus rostralis indistinct, oblique; loreal concave; nostrils oval, laterally positioned and obliquely oriented; nostril closer to snout tip than eye; snout anteriorly depressed at internarial space; internarial space equal to inter-upper eyelid width and upper eyelid width; eyes protruding, moderate in size, less than half of head length ( EL / HL = 0.42); tympanum distinct, round, nearly half of eye length ( HTYD / EL = 0.47); tongue posteriorly notched; choanae round; vomerine teeth present between choanae and angular to body axis; a pair of internal vocal sac openings on lower jaw; habitus stout, its length nearly half of snout-vent length ( AG / SVL = 0.47).

Forelimbs slender; forearm length smaller than hand length ( FAL / HAL = 0.71); third finger longest; fingers with rounded disc; disc on third and fourth finger nearly equal to tympanic diameter; circum-marginal groove present on disc; subarticular tubercles rounded and distinct; supernumerary tubercles present; palmar tubercles distinct, oval shaped; rudimentary webbing present between fingers; nuptial pad not visible.

Hindlimbs comparatively stout; thigh length and tibia length equal, less than half of snout-vent length ( TL / SVL = 0.43); foot length greater than thigh and tibia length ( TL / FOL = 0.96); fourth toe longest; toes with rounded discs; toe discs width slightly smaller than that of fingers; circum-marginal groove present on discs; subarticular tubercles distinct and rounded; supernumerary tubercles absent; inner metatarsal tubercle present; outer metatarsal tubercle absent; webbing moderate, reaching first subarticular tubercle on fourth toe.

Skin on dorsal aspect of snout and head smooth with numerous enlarged, distinct spinules including on upper eyelids; similar spinules on loreal region, below eyes, and on mandibular region; skin on dorsum smooth with numerous spinules, which decrease in number posteriorly; flank with flat granular tubercles; ventrum of head and chest smooth; abdomen granular; granules on thigh indistinct; flat tubercles below vent; forelimbs, tibia, and tarsus smooth.

Colouration in life (based on specimen WII-ADA 1773 ; Fig. 8 F).

Top and lateral sides of head brown; tip of snout with enlarged olive-brown patch to below nostrils and vertical pale yellow line at tip of snout; a similarly coloured spot in front of interorbital space; olive-brown stripe on loreal region below canthus rostralis; a similarly coloured patch below eyes, bordered with pale yellow; dark brown iris with irregular golden patches; olive-brown streak along anterior part of supratympanic fold and a few irregular spots on tympanum; dorsum pale yellowish brown with enlarged olive brown hourglass shaped patch, starting from interorbital space and covering posterior half of upper eyelids, posteriorly bifurcating in middle of dorsum, directing towards groin as gradually diffusing; two pale yellowish brown spots on dark patch, one on back of head and another elongated one on anterior part of back; flank pale brown with some irregular small olive-brown spots; dorsum of forelimb pale yellowish brown; broad olive-brown band on forearm; similar patch on base of hands and dorsal aspect of fingers; hindlimbs pale yellowish brown on top with three broad olive-brown, irregular bands on each thigh and tibia; small patch of similar colour on knees; similar bands on tarsus, base of foot, and on dorsal aspect of toes; ventrum of head, abdomen, and limbs uniform pale cream coloured.

Colouration in preservative.

Dorsal aspect of head, dorsum, and limbs brown; markings on head, dorsum, and limbs visible as in life; ventrum of head, back and limbs uniform pale brown.

Morphological variation.

Overall, the newly collected material from the type locality of “ R. sahai ” similar to the types of N. jerdonii . However, following variations were observed among the individuals. Head slightly wider than length in WII-ADA 1773 which is similar to that of holotype of “ R. sahai ” ( ZSIA 8500 ). However, in the paratype ( ZSIA 8501 ) and two newly collected specimens ( WII-ADA 3240 and WII-ADA 1770 ), head length is equal to head width. Snout length is equal to eye length in the type specimens of “ R. sahai ” ( ZSIA 8500 , ZSIA 8501 ), but slightly shorter in the newly collected specimens. Snout length greater than eye length in the types of N. jerdonii ( BMNH 1947.2.7.84 , BMNH 1947.2.7.85 ). Inter-upper eyelid width greater than upper eyelid width in the types of “ R. sahai ” ( ZSIA 8500 , ZSIA 8501 ) and types of N. jerdonii ( BMNH 1947.2.7.84 , BMNH 1947.2.7.85 ). Inter-upper eyelid width is equal to the upper eyelid width in WII-ADA 1773 and in two specimens ( WII-ADA 3240 and WII-ADA 1770 ), inter-upper eyelid width is smaller than upper eyelid width. Internarial distance equal to inter-upper eyelid width in the types of “ R. sahai ” ( ZSIA 8500 , ZSIA 8501 ) and WII-ADA 1773 . Internarial distance equal to inter-upper eyelid width in the types of “ R. sahai ” ( ZSIA 8500 , ZSIA 8501 ) and WII-ADA 1773 while internarial distance greater than inter-upper eyelid width in WII-ADA 3240 and WII-ADA 1770 . Internarial distance smaller than inter-upper eyelid width in the types of N. jerdonii ( BMNH 1947.2.7.84 , BMNH 1947.2.7.85 ). Tibia length smaller than thigh length in types of “ R. sahai ” ( ZSIA 8500 , ZSIA 8501 ) and the two topotypes ( WII-ADA 3240 and WII-ADA 1770 ) but thigh length and tibia length equal in WII-ADA 1773 . Tibia length greater than thigh length in the types of N. jerdonii ( BMNH 1947.2.7.84 , BMNH 1947.2.7.85 ). A detailed morphometric variation of the newly collected material is provided in Table S 11. Dorsal markings on head, dorsum and limbs of the types are barely visible unlike the topotypes. In addition, WII-ADA 3240 has a distinct nuptial pad on the first finger; irregular shaped and sized brown patches present on ventrum of head, chest, and forelimbs of WII-ADA 1770 .

Distribution and natural history.

Nasutixalus jerdonii is widely reported from northeast India ( Biju et al. 2016). It was previously reported from Darjeeling ( Günther 1876); Mawphlang Sacred Grove, Wahlynkien (Marai Kaphon), Cherrapunji in Meghalaya; Zaraengtung, Raenghzaeng Village in Manipur; Sechüma village, Zubza, Meriema Village, Seukwehii, Tseminyu Village in Nagaland ( Biju et al. 2016); Hmuifang Community Reserve Forest, Murlen National Park in Mizoram ( Muansanga et al. 2022). Rahman et al. (2020) reported this species from Ziradum, Myanmar. Zug (2022) reported this species from northern Myanmar ( Kachin). During our study, we recorded the species from Gandhigram and near Glaw Lake at Kamlang Tiger Reserve in Arunachal Pradesh, and in Hmuifang, Mizoram. At Gandhigram, subadult individuals were recorded on leaves at a height of ~ 20 cm above ground near a small stream ~ 300 cm wide at around 20: 00 hrs. Adult individuals were recorded on leaves at a height of ~ 100 cm above ground at around 22: 00 hrs in September 2022. Calling males were observed active among tree ferns at three meters above ground in late May.

Figures

Figure 7. “ Raorchestes sahai ” (= Nasutixalus jerdonii). A – C Holotype of “ R. sahai ” (ZSIA 8500). A Dorsal view, B ventral view, C lateral view of head; D – I paratype of “ R. sahai ” (ZSIA 8501). D Dorsal view, E ventral view, F lateral view of head, G ventral view of left hand, H ventral view of left foot; I – J vomerine teeth in paratype and holotype respectively. Scale bar = 10 mm.

Figure 8. A ML tree inferred from 16 S mitochondrial gene. UFB values below 50 are not shown on tree. Scale bar represents substitution per site. Newly collected specimens of N. jerdonii from type locality of “ R. sahai ” Gandhigram, Arunachal Pradesh; B – E topotypic collection WII-ADA 1773 in preserved condition; F WII-ADA 1773 in life; G – H WII-ADA 1770 in preserved condition. Scale bar = 10 mm.