Bioacoustics of Raorchestes kakachi

Diagnosis. Small sized adult Raorchestes (male: 24.7–25.8 mm , n = 3 and female: 24.3–34.1 mm , n = 3) diagnosed with the following characters. Absence of vomerine teeth; translucent vocal sac while vocalizing; active during night (observed between 18:00–23:00 hrs); all digits well differentiated with discs having distinct circummarginal grooves; absence of dermal folds and spur in forelimbs and hindlimbs. It is distinguished by all other congeners by the following combination of characters: (i) flat head; (ii) snout oval in dorsal view; (iii) tympanum indistinct; (iv) supra-tympanic fold distinct; (v) head wider than long; (vi) skin granular on throat, chest, belly, flanks, vent and lower parts of thigh; (vii) tuberculate projections on dorsum, upper eye lids, snout, tympanic region, fore limbs and hind limbs; (viii) colour on dorsum varying from ivory to brown, blotches of dark brown on flanks, brown mottling on throat reducing towards vent; (ix) fingers and toes with well developed discs, circummarginal groves folding upwards giving a bifid appearance in dorsal view; (x) intercalary ossification distinct, present between penultimate and distal phalanges of both fingers and toes as a white glandular projection; (xi) moderate webbing in hind limbs; (xii) distinct dark brown horizontal band on inner and outer surface of thigh, inner surface of shank and inner surface of tarsus extending up to first three toes on upper surface; and (xiii) iris colour brown.

Variation ( Figure 4. a–c ): Details of the morphometric variations observed in 6 individuals is provided in Table 1. Morphologically, the dorsum colouration among males varied from dark brown to buff. One male individual (ZSI/WGRC/V/A 858, Figure 4. c ) was with coffee brown dorsum, ivory patches on lower part of tympanic region, loreal region, shoulder, knee and heel. Ivory spots on upper part of flank, lower dorsum, dorsal part of hand and foot. Variations also included distinct cross bands on both forelimbs and hind limbs, straw yellow colouration on the lower dorsum and overall dark reddish colouration on anterior dorsum. In females, the patch on head was uniform. Among immature females, the dorsum colour varied from pale brown to dark brown similar to that of males. Comparisons. Raorchestes kakachi sp. nov. can be confused with R. flaviventris (Boulenger) and R. kaikatti (Biju & Bossuyt) by its overall morphology. However, R. flaviventris differs from R. kakachi sp. nov. in the following characters: tongue with lingual papilla vs. absent, tympanum distinct vs. indistinct, thigh length equal to shank length (ThL = 13.5 mm , ShL = 13.5 mm ) vs. thigh length shorter than shank length (male, ThL = 12.1 ± 0.2 mm , ShL = 13.1 ± 0.4 mm , n = 3; female, ThL = 14.4 ± 2.2 mm , ShL = 15.1 ± 2.1mm , n = 3), webbing between fingers rudimentary vs. absent, dermal fringe on fingers absent vs. present, ventral side grey and dark-brown vermiculated throughout vs. ventral side grey with brown mottling reducing towards vent, forelimbs, tibia and foot, dorsal and posterior part of thigh brown with cream dots vs. distinct dark brown horizontal band on inner and outer surface of thigh, inner surface of shank and inner surface of tarsus extended up to first three toes on upper surface. R. kaikatti differs from R. kakachi sp. nov. in the following characters: head length equal to head width (male, HW = 9.6 ± 0.4, HL = 9.5 ± 0.4 mm ) vs. head wider than long (male, HW = 9.4 ± 0.4, HL = 8.1 ± 0.5 mm ; female, HW = 11.16 ± 2, HL = 9.3 ± 1.5 mm ), thigh length equal to shank length (male, ThL = 12.5 ± 0.9 mm , ShL = 12.3 ± 0.8 mm , n = 5) vs. thigh length shorter than shank length (male, ThL = 12.1 ± 0.2 mm , ShL = 13.1 ± 0.4 mm , n = 3; female, ThL = 14.4 ± 2.2 mm , ShL = 15.1 ± 2.1 mm , n = 3), ventral side greyish white vs. brown mottling, posterior part of thighs and groin brown vs. distinct dark brown horizontal band on anterior and posterior parts of thigh, inner surface of shank and inner surface of tarsus extended up to first three toes on upper surface. The comparison provided above for R. kaikatti is based on the examination of the name bearing types at BNHS but that of R. flaviventris are based on original descriptions provided in Bossuyt and Dubois (2001) and Biju and Bossuyt (2009) since the specimen itself is located outside India . Details of name bearing types examined by authors has been provided in Appendix I and major opposing suite of morphological characters of all other species in Raorchestes found in the Western Ghats except R. flaviventris and R. kaikatti are provided in Appendix II. Ecology and natural history notes. Two individuals (ZSI/WGRC/V/A/858: one male and one female) of this species were first collected on bushes up to 2 m height along streams on riparian vegetation next to the road in Kakachi by KSS, NAA, TG and RG on 24th January 2011 at 20:30 hrs. Subsequently, on 24th May 2011 , a pair (ZSI/ WGRC/V/A/859: one male and one female) in axillary amplexus was observed and collected on forest floor in the same location by KSS and PS from 20:49 hrs to 21:30 hrs. The amplecting pair was carried to laboratory where they were observed for egg laying in a terrestrial enclosure. The amplecting pair dismounted and the female laid six eggs and a few more eggs were visible in the abdomen. The eggs were non-pigmented with jelly mass and measured ( 2.2 mm , n = 3). However, we did not make any further observation on egg development. FIGURE 6. Spectrogram of an advertisement call of Raorchestes kakachi sp. nov. (ZSI/WGRC/V/A/ 857) measuring 6.54 sec in duration recorded from Kakachi on 23rd June 2011 at 19:08 hrs. Dominant frequency of this call 2625 Hz, pulse duration 0.05 sec, pulses 9, pulse rate 1.77 sec–1. a. Amplitude; b. Spectrogram and c. Band width. Between May and June 2011 , three individuals were observed and photographed (not collected) to be foraging in the canopy of Cullenia exarillata ( 32 m ) and Diospyros sp. ( 30 m ) trees between 19:00–21:15 hrs in forests around Kakachi and Upper Kodayar. The canopy was accessed at night using modified single rope technique ( Perry 1978 ). Two calling males were collected from 2 m high vegetation along a stream in Kakachi on 24th June 2011 . The calls of these two individuals were recorded for analysis. An amplecting pair was observed the next day ( 25th June 2011 ) on the same location on roadside tree at 4 m height from 19:23 hrs–21:30 hrs but did not lay eggs. In another location, a male and female were observed in the sub-canopy (ca. 15 m ) of roadside trees. A male Ramanella montana was seen mounting with a female of R. kakachi sp. nov. for about 5 min after which, the pair disengaged in the same location. A long term monitoring study by KSS in KMTR using automated sound recorders have recorded the species to be vocalizing in the canopy and on the ground. The vocalization begins at about 18:30 hrs and the number of individuals and their vocalizing intensity reaches a peak between 18:00–20:30 hrs. Initially the calls were heard from the canopy and the frogs were detected on the ground at about 19:00 hrs. Though many individuals of this frog were observed in the canopy in both Kakachi and Upper Kodayar, the individuals described in this paper were collected on ground and on natural vegetation in estate, either before the frog went up into the canopy or after they descended from there. Advertisement call analysis. Calls were recorded using Nikon D90 DSLR camera within 20–30 cm from calling males at night (19:00–21:30 hrs). The air temperature and humidity at collection time were (23°C and 86% RH, measured using Kestrel 3500®, data logger). Eight calls from two calling males were analyzed using Audacity Ver.1.3 (Beta) and SIGVIEW 32 Ver.2.3.0. Call terminology was based on Kok and Kalamandeen (2008) . Each call had 6–9 pulses ( treek, treek, treek ,…pulses). Average dominant frequency was 2637.25 ± 14.1 Hz (range: 2630–2651 Hz), Call duration was 4.98 ± 0.8 sec (range: 3.4–6.5 sec), inter call duration was 1.46 ± 0.7 sec (range: 0.6–2.2 sec), pulse duration was 0.74 ± 0.07 sec (0.6–0.9 sec), pulse period was 0.05 ± 0.006 sec (range: 0.04–0.07 sec) and pulse rate was 1.54 ± 0.1 sec -1 (range: 1.37–1.75 sec -1). Figure 6.a–c illustrates the amplitude, call spectrum and peak frequency of a single call (ZSI/WGRC/V/A 857). A short video clip of the frog vocalizing can be found on Amphibia web, 2012 (http://tinyurl.com/raorchestes-kakachi).