Nyctibatrachus tunga, Kumar & Vishwajith & Anisha & Dayananda & Gururaja & Priti, 2022

Kumar, K. S. Pavan, Vishwajith, H. U., Anisha, Anand, Dayananda, G. Y., Gururaja, Kotambylu Vasudeva & Priti, Hebbar, 2022, A new cryptic species of Nyctibatrachus (Amphibia, Anura, Nyctibatrachidae) with description of its tadpole from the central Western Ghats, India, Zootaxa 5209 (1), pp. 69-92 : 75-79

Nyctibatrachus tunga sp. nov.

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( Table 1 , Figure 3a–j ). Holotype. BNHS 6102 , an adult male, collected on 20-12-2020 by HUV along a stream inside a coffee plantation at Siddaramata village , Koppa Taluk, Chikkamagaluru District, Karnataka State, India ( Figure 3a , 13.61083 °N, 75.39847 °E, 721m amsl) . Paratypes. Adult males (2 individuals, BNHS 6103 , BNHS 6104 ) and adult females (2 individuals, BNHS 6105 , BNHS 6106 ) collected by HUV, KSP and KVG at the same stream as that of holotype on 28-02-2020. Tadpoles. BNHS 6107–6112 tadpoles (n=6) were collected by HP, HUV, KSP and KVG at the same stream as that of holotype on 10-09-2019 .

Diagnosis. This species is assignable to the genus Nyctibatrachus because of its semi-aquatic to aquatic habitat, medium to large size, diamond-shaped pupil, glandular wrinkled skin, presence of vomerine teeth, notched tongue, finger and toes with discs, absence of webbing on fingers and presence of webbing on toes and presence of subocular gland ( Biju et al. 2011). Nyctibatrachus tunga sp. nov. can be easily distinguished from all other species in the genus by the following combination of characters: (1) adult male size medium (SVL 38.6± 1.6 mm, n=3), (2) head wider than long (HW 16.0– 17.6 mm; HL 11.7–13.6 mm), (3) dorsum glandular without any spiny projections in the anterior half, glandular corrugations irregular without specific pattern; in males, throat and chest finely dotted with glandular folds rest of the region smooth, belly white, (4) webbing on toes medium (I 0 – ½ II 0 – 2 III 0 – 3 IV 3 – 0 V), (5) presence of nuptial pad and femoral glands in adult males, (6) dorsal body color dark brown, ventrally buff colored except belly, (7) finger disc weakly developed (fd3 0.8± 0.1 mm; fw3 0.5± 0.1 mm), (8) toe disc moderately developed (td4 1.2± 0.2 mm; tw4 0.8± 0.1 mm), (9) third finger disc without dorso-terminal groove, fourth toe disc with dorso-terminal groove cover bifurcate distally, (10) genetically belongs to N. sanctipalustris clade including N. kumbara (3.30% for 16S, data for ND1 not available), N. dattatreyaensis (3.74% for 16S and 12.91% for ND1), N. vrijeuni (2 % for 16S and 8.22% for ND1), N. shiradi (2.64% for 16S and 7.75% for ND1), N. karnatakaensis (3.52% for 16S and 11.03% for ND1) and N. sanctipalustris (3.30%for 16S and 13.62% for ND1).

Description of the holotype. BNHS 6102, adult male ( Figure 3a–j ), terminology follows Gururaja et al. (2014). Morphometric data are given in Table 1.

A medium-sized species of Nyctibatrachus (SVL 38.6 mm); habitus compact and squat; head wider (HW 17.2 mm) than long (HL 12.2 mm; MN 10.9 mm; MFE 8.6 mm; MBE 3.6 mm), rounded in anterior view; snout rounded (SL 6.1 mm), marginally protruding, its length longer than horizontal diameter of eye (EL 5.0 mm); canthus rostralis rounded; loreal region concave; interorbital space flat (IUE 4.3 mm) and double the upper eyelid width (UEW 1.9 mm); more than internarial distance (IN 3.6 mm); distance between back of eyes (IBE 12.3 mm) is greater than double the distance between front of eyes (IFE 5.9 mm); nostrils oval, without a flap of skin, and is closer to eye (EN 2.3 mm) than snout tip (NS 3.2 mm); eyes large (EL/HL = 0.41) protruding on the sides of head, its diameter more than eye to nostril distance (EL/EN = 2.8); pupil rhomboidal; tympanum indistinct; subocular gland distinct ( Figure 3e ); pineal ocellus absent; vomerine ridge present posterior to choanae, oval bearing three on left and 3 sharp spinose teeth on right ridge; symphysial knob ‘ᗯ’ shaped, moderately developed; tongue moderate, oval emarginate, median lingual process absent; parotoid glands, cephalic ridges and co-ossified skin absent.

Forelimbs (FLL 8.5 mm) strong and smaller than hand length (HAL 9.7 mm); third fingers thin, long, rounded (TFL 5.1mm); thin dermal fringe on finger III; webbing absent ( Figure 3f ); relative length of fingers, shortest to longest: I<II<IV<III; tips of fingers enlarged with weakly developed disc and third finger disc without dorsoterminal groove ( Figure 3h ) subarticular tubercles moderate, oval one each on finger I and II and one oval and one round (two) each on finger III and IV; prepollex oval and palmar tubercle distinct ( Figure 3f ).

Hind limbs moderately long; tibia length (TL 19.4 mm) more than two times longer than wide (TW 7.3 mm), shorter than femur length (FL 20.6 mm) and sub-equal to the distance from the base of the internal metatarsal tubercle to the tip of toe IV (FOL 19.1 mm); heels do not touch when the tibia are folded at right angles to the body; toes thin and long; toe IV long (T4L 10.1 mm) and less than the distance from the base of the tarsus to the tip of toe IV (TFOL 28.4 mm); relative length of toes, shortest to longest: I<II<III<V<IV ( Figure 3g ); tips of toes with moderately developed discs and fourth toe disc with dorso-terminal groove, cover bifurcate distally ( Figure 3g and 3i ), webbing medium (3/4 th) (I 0 – ½ II 0 – 2 III 0 – 3 IV 3 – 0 V) (MTTF 12.4 mm; MTFF 11.7 mm; TFTF 6.5 mm; FFTF 7.6 mm) ( Figure 3j ); dermal fringe along toe V distinct; subarticular tubercles present, moderate, pear shaped, one each on toe I and II, two each on toe III and V, and three on toe IV; inner metatarsal tubercle elongate and prominent; its length (IMT 2.6 mm) shorter than toe I (T1L 3.5 mm) length; outer metatarsal tubercle, supernumerary tubercles and tarsal tubercles absent ( Figure 3g ).

Skin is corrugated on the dorsal and lateral surfaces of the body with glandular folds; dorsal surface forelimbs and hind limbs with short longitudinal glandular folds; upper eyelids with three rows of glandular folds, short longitudinal glandular folds arranged in three arching series behind eye till shoulder, four similar folds arranged on dorso-lateral sides of the body from the plane above shoulder till groin, snout with a ‘Y’ shaped fold from middle of upper lip, its arms bifurcating between nares and running towards orbits; supratympanic fold and subocular fold distinct. A prominent horizontal fold connecting upper eyelids, an inverted ‘V’ shaped oblique fold on the mid dorsum and in between these two folds, two shorter prominent folds. Four pairs of prominent short glandular folds from mid dorsum till the plane of groin; Throat with dense glandular longitudinal folds and rest of the venter soft glandular without any folds; belly smooth; thigh ventrally smooth ( Figure 3d ); dorsally tarsus, heel, and knee with fine spinules ( Figure 3c ). femoral gland present (FGL 8.0 mm; FGB 2.4 mm).

Color of holotype. In life: iris golden yellow in its upper part, pupil rhomboidal, black in color ( Figure 3a and b ). Sides of head light-colored, the region between the subocular gland and tympanic region cream-colored. A black horizontal band connecting upper eyelids. Dorsum brown with two light brick red dorsolateral bands laterally bordered by dark brown from orbits to vent. Region between dorsolateral bands is light brown with three black horizontal bands, one at between orbits, one at anterior region of shoulders and other at posterior region of shoulders. Forearm barred with small, black and larger dark brown bands; hind limbs barred with small light brick red and larger dark brown bands. Sides of the body brownish. Nuptial pads on base of first fingers cream colored. Throat translucent with fine black spots on the glandular skin. Chest, belly, and anterior part of thighs translucent. Posterior part of thigh with raised pale white femoral gland in males.

In preservative ( Figure 3c ) dorsal and lateral parts of body mottled with brown and cream color, with a pair of faint dorsolateral lines from posterior orbit to above vent; faint horizontal band between eyes; femoral glands cream white; dorsal parts of limbs, forelimbs, femur, tibia and foot up to tip of fingers and toes barred; throat and chest pale brown; belly and thighs white; femoral glands granular, pale white in color ( Figure 3d ).

Secondary sexual characters. Males have a nuptial pad covering the base of the dorsal surface of the first finger and a pair of femoral glands which are more than 3.5 times longer (FGL 8 mm) than wide (FGB 2.3 mm) and are conspicuous both in life and preservative ( Figure 3d ). Females have pigmented eggs.

Additional information from paratypes and variation. Morphological data of paratypes and variation are given in Table 1 . All individuals are collected from type locality. Skin swabs from adult individuals and tail tip of a tadpole were obtained from the second locality ( Nemmar village , Sringeri Taluk, Chikkamagaluru District, Karnataka State, India, 13.34325°N, 75.25337°E) for identification and is used in building phylogenetic tree. We did not collect or measure morphological data from these individuals. Male individuals from type locality are smaller (37.0– 40.2 mm, n=3) than female individuals (42.4–47.4 mm, n=2) exhibiting sexual dimorphism. Males have femoral glands, while females do not have them. In all the external morphological features they are similar to holotype. In all the specimens of Nyctibatrachus tunga sp. nov. fourth toe disc with dorso-terminal groove, cover bifurcate distally and webbing medium, reaching third subarticular tubercle on either side of toe IV (I 0 – ½ II 0 – 2 III 0 – 3 IV 3 – 0 V). Photographs of ventral side of foot of all the type specimens of the new species can be accessed from DOI: 10.5281/zenodo.7071991

Etymology. The specific epithet is derived from the name ‘Tunga’. The species is recorded in the catchment areas of the river Tunga and the species epithet is a noun in apposition to the generic name.

Suggested common name. Tunga River Night Frog.

Distribution and Natural History. Nyctibatrachus tunga sp. nov. is observed from the upper catchment area of River Tunga as shown in Figure 1 . Adults and tadpoles were observed from streams at Nemmar village, Sringeri Taluk, Chikkamagaluru District, Karnataka State, India (13.34325°N, 75.25337°E, 700m amsl). They were identified using molecular analysis of skin swabs and tadpole tail tips and are used in the phylogenetic tree. Uncorrected p values between the individuals of type locality and this locality is in the range of 0.22 to 0.44, confirming the identity of Nyctibatrachus tunga sp. nov. We did not collect these individuals. There is a possibility that it is more widespread and occurs beyond its currently known localities. Based on our field observations, this species is locally abundant in the surroundings of the type locality and is restricted to perennial streams of the coffee estates, evergreen, and semi-evergreen forests. Canopy cover of the streams ranged between 80-90%, with stream width ranging from 47–50 cm and stream depth ranging from 3.0– 4.4 cm. Water temperature ranged between 21.5–22.1°C. The air temperature was 25.9±0.3 °C, relative humidity was 66.2±0.07%. Streams had small gravels, sand, and leaf litter with intermittent big boulders. Water in the stream was slow flowing.

Figures

FIGURE 1. Distribution records of Nyctibatrachus tunga sp. nov. along with its sister taxa N. vrijeuni and N. shiradi, Western Ghats, India. Circle with blue dot is N. shiradi, circle with red dot is Nyctibatrachus tunga sp. nov. and circle with black dot is N. vrijeuni.

FIGURE 3. Habitat and holotype (BNHS 6102) of Nyctibatrachus tunga sp. nov. a–Slow flowing stream habitat of the holotype; b–Live individual of holotype; c–Dorsal view; d–Ventral view; e–Lateral profile of head; f–Ventral view of Forelimb; g–Ventral view of Hindlimb; h– third finger disc without dorso-terminal groove; i– fourth toe disc with dorso-terminal groove cover bifurcate distally; j–Schematic view of webbing in hindlimb. (Scale bar = 5mm).