Bioacoustics of Minervarya ghatiborealis

Generic Allocation. Minervarya ghatiborealis sp. nov. is assigned to the genus Minervarya based on a suite of characters as demarcated by Dubois et al . (2001) and Garg & Biju (2021) such as large adult size ( SVL ranging 55.0– 67.1 mm ) presence of vomerine ridge; presence of parietal eye; weakly to well developed and a light greyish-brown glandular stripe extending from the lower half of the tympanum up to the level of the shoulders on either side; presence of fejervaryan lines on either side of the belly; absence of webbing between fingers; webbing between toes rudimentary; absence of finger and toe discs; presence of skin folds, with rugged glandular warty folds on the dorsum; and smooth ventral skin; front and back of thighs with yellow brown reticulated markings. Description of the holotype . Specimen is in good condition except for a small mid-ventral incision for removal of liver sample ( Figs 4A–B ). A large-sized minervaryan frog with robust body (SVL = 59.1 mm ), head length equal to head width (HW/HL = 1.0), snout shape sub-elliptical in dorsal view, rounded in lateral view, snout length (SL = 8.4 mm ) longer than eye diameter (EL = 7.0 mm); canthus rostralis round, loreal region concave, interorbital space flat, less than (IUE = 3.7 mm ) upper eyelid width (UEW 4.7 = mm) and internarial distance (IN = 5.1 mm ); distance between back of eyes 1.7 times more than front of eyes (IFE = 7.9 mm ; IBE = 13.3 mm ); nostril rounded, as close to the tip of snout (NS = 3.7 mm ) as to the eye (NE = 3.8 mm ); symphysial knob moderate, ‘W’ shaped; tympanum distinct, rounded visible below the well-developed supratympanic fold ( Fig. 4C ) and about 48.3% of the eye diameter (TYD = 3.4 mm ; EL = 7.0 mm) and placed closer to eye (TE = 2.3 mm ); paired lateral vocal sac with a pair of openings at the base of lower jaw; vomerine ridges present with six spinose teeth; tongue bifid without a lingual papilla. Arms slender and short (FLL = 12.5 mm ) sub equal to hand (HAL = 13.1 mm ); fingers short and thin without dermal fringes; first finger slightly longer than the second (FL1 = 5.4 mm , FL2 = 4.7 mm ) third finger is longest (TFL = 7.1 mm ), relative length of fingers II<I<IV<III, tips bluntly rounded without enlarged discs, webbing absent; subarticular tubercles distinct and rounded, subarticular tubercle on fingers 1:1:2:2, pre-pollex tubercle distinct; two rounded palmar tubercles; no supernumerary tubercles ( Fig. 4E ). Hind limbs long, overlap when folded at right angles to the body; tibio-tarsal articulation reaches front of eyes; femur length sub equal to tibia length (FL = 28.5 mm ; TiL = 29.4 mm ); foot length is two times tarsus length (FOL = 32.0 mm, TAL = 16.0 mm), relative toe length I<II<V<III<IV (FTL = 19.5 mm ); webbing rudimentary (I 2–2 II 11/2 –3 III 2–3 IV 21/2 –2 V); inner metatarsal tubercle (IMTL = 3.6 mm ) large elongated and shovel shaped; outer metatarsal tubercle small, bulbous; subarticular tubercles distinct and rounded, subarticular tubercles on toes 1:1:2:3:2; no supernumerary tubercles and tarsal tubercle minute ( Fig. 4D ). Dorsal skin shagreened bearing glandular projections with tubercles and small longitudinal glandular ridges; upper eyelids sparsely tuberculate; flank shagreened with prominent granular projections and scattered glandular warts; ventrally smooth on throat and belly. Fejervaryan lines present along both sides of the belly ( Fig. 4A, B ). Colouration in life ( Figs 3 , 6 ). Dorsum greyish-brown with olive-brown blotches; lateral surfaces of head lighter than dorsum; upper, lower lip, fore arm and hind limbs with prominent crossbands, greyish-brown alternating with light grey; light greyish yellow dorsolateral stripe from tip of snout to back of vent on the dorsal surface; thighs reticulated with brown and olive; webbing light grey. Ventrally, throat was creamish white colour with black vocal sacs; belly white. Iris golden yellow, darker towards the periphery and lighter towards the center, pupil black. Colouration in preservation ( Fig. 4 ). Dorsum blackish brown, a thin creamy white dorsolateral stripe from tip of snout to back of vent on the dorsal surface; upper and lower jaw margins with black crossbands alternating with cream white; forelimbs and hind limbs are barred with dark grey transverse bands; Back of thighs reticulated with dark brown and cream white. Ventrally, throat with blackish vocal sacs; belly white. Variation and additional information from paratopotype series. Morphological data are given in Table 2 including holotype . Paratopotypes SVL range from 55.0 mm to 67.1 mm . NRC-AA-8437 has tubular sac like outgrowth near right vocal sac ( Fig. 5 ). Secondary Sexual Characters. Adult calling males have nuptial pads present on the first fingers and blackish bilobate vocal sacs present at the region of throat. Females are larger than males.

Distribution and natural history . Minervarya ghatiborealis sp. nov. is currently known only from its type locality, Mahabaleshwar in Satara District, northern Western Ghats of Maharashtra . During the early monsoon (June), a few gregariously calling males were observed around ephemeral water bodies in an open parking area near residential buildings and in syntopy with Minervarya goemchi ( Fig. 9 ) and M. syhadrensis . At around 21.00 hours, male and female frogs were spotted in axillary amplexus ( Fig. 6D ). This species was observed only for a very short duration of few weeks during the breeding season. Neither breeding activity nor adult individuals were observed after the breeding season.

Vocalization. The advertisement call oscillograms and spectrogram of holotype ( ZSI / WRC /A/2702) of Minervarya ghatiborealis sp. nov. is given in Fig. 7A–C . An advertisement calls of new species had an average call duration of 0.614s (± 0.014s ) with average pulses 36 (± 1) delivered at a rate of 58 pulses per second. The interval between notes is 1.15 ± 0.18 (0.98–1.52) seconds. Average dominant frequency was 2494.9 ± 24.5 Hz (2422–2510 Hz). The advertisement call oscillograms and spectrogram of M. goemchi is given in Fig. 7D–F . An advertisement calls of this species had an average call duration of 0.442 ± 0.014s ( 0.423 – 0.477 s) with average pulses 15 ± 0.53 (14–16) delivered at a rate of 34 pulses per second. The interval between notes is 1.45 ± 0.27 (1.14–2.14) seconds. Average dominant frequency was 2828.6 ± 68 Hz (2725.4–2925.9 Hz). Call duration and the number of pulses were significantly higher in M. ghatiborealis sp. nov. (Mann Whitney test: Z = 4.6, p -value = 0.00064 and Z = 4.8, p -value = 0.0000016 respectively) however dominant frequency and intercall interval duration were significantly lower in M. ghatiborealis sp. nov. (Z = -4.7, p -value = 0.00000264 and Z = -2.9, p -value = 0.002921 respectively).