Hylarana doni sp. nov.
Don’s Golden-backed frog
Holotype. BNHS 5814, an adult male, Padagiri, Nelliyampathy, Palakkad dist., Kerala state, India, collected by SDB and SG, 15 October 2011.
Paratypes. BNHS 5815, an adult male, collected along with holotype; BNHS 5816, an adult male and BNHS 5817, an adult female, Poomala, Idukki dist., collected by SDB and Systematics Lab team, 21 April 2012; BNHS 5818, an adult male, Parambikulam tiger reserve, Palakkad dist., collected by SDB and Systematics Lab team, 11 August 2011; BNHS 5819, an adult male, Thekkady, Idukki dist., collected by SDB, 23 July 2005; BNHS 5820, an adult male, Chathankod, Thiruvananthapuram dist., collected by SDB, 23 May 2006; BNHS 5821, an adult male, Chathankod, Thiruvananthapuram dist., collected by SDB and Systematics Lab team, 11 September 2011; BNHS 5822, an adult male, Gavi, Pathanamthitta dist., collected by SDB, 10 June 2007.
Referred specimens. SDBDU 2011.540, an adult male, Parambikulam tiger reserve, Palakkad dist., collected by SDB and Systematics Lab team, 11 August 2011; SDBDU 2011.265, an adult male, Chathankod, Thiruvananthapuram dist., collected by SDB and Systematics Lab team, 11 September 2011; SDBDU 2011.1169, an adult male, Kesavapara, Nelliyampathy, Palakkad dist., collected by SDB and SG, 14 October 2011; SDBDU 2006.4824, an adult male, Gavi, Pathanamthitta dist., collected by SDB, 10 June 2007; SDBDU 2006.4845a, a sub-adult, Palode, Thiruvananthapuram dist., collected by SDB, 6 October 2006.
Comparison. Hylarana doni sp. nov. could not be confused with Hylarana aurantiaca, Hylarana intermedius and H. urbis sp. nov. within the Hylarana aurantiaca group due to its relatively large adult male snout-vent size, SVL 38.0-43.1 mm, N = 12 (vs. SVL 27.1-31.7 mm, N = 9, H. aurantiaca, SVL 33.0-41.6 mm, N = 14, H. intermedius, SVL 30.1-34.3 mm, N = 5, H. urbis) and ventral side of the forearm with a straight line of granular projections from the base of finger IV to the elbow (vs. absent in all three species) (Figs 8b, e, h, k). Furthermore, H. doni differs from H. intermedius by its shank longer than foot length, male SHL 21.7 ± 1.3 mm, FOL 19.8 ± 1.0 mm, N = 12 (vs. equal, male SHL 17.9 ± 0.9 mm, FOL 17.9 ± 0.9 mm, N = 14) and fourth toe webbing not extending beyond the second subarticular tubercle on the outside (vs. well beyond); differs from H. urbis by its dorsolateral folds moderately developed (vs. weakly developed), granular dorsal skin (vs. shagreened) and relatively more webbing I1-2II1-2+III1-3IV3-1V (vs. less I2--2+II1¾-2¾III2--3IV3-1¾ V) (Figs 8e-f, k-l). See Hylarana aurantiaca for comparison with that species.
Genetic divergence. Intraspecific genetic variation within Hylarana doni was 0.2 ± 0.2% (range 0-0.6%, N = 8) for 16S, 0.4 ± 0.3% (range 0-1.0%, N = 9) for COI and 0.5 ± 0.5% (range 0-1.2%, N = 10) for Cytb. Based on phylogenetic position, H. doni is closely related to the members of Hylarana aurantiaca group (Fig. 4); differs from H. intermedius by mean genetic divergence of 2.7 ± 0.1% (range 2.6-3.0%, N = 72) for 16S, 6.1 ± 0.3% (range 5.5-6.7%, N = 81) for COI, and 9.1 ± 0.1% (range 8.0-12.1%, N = 90) for Cytb; differs from H. urbis by mean genetic divergence of 4.3 ± 0.1% (range 4.3-4.5%, N = 24) for 16S, 8.4 ± 0.2% (range 8.1-8.8%, N = 27) for COI, and 10.1 ± 0.6% (range 9.5-11%, N = 30) for Cytb (Tables S2-S3). See Hylarana aurantiaca for comparison with that species.
Description of holotype (Figs 7d-f, 8d-f). Small-sized, slender adult male (SVL 42.0). Head small (HW 11.8, HL 15.6, IFE 7.9, IBE 10.1), longer than wide, flat above; snout sub-elliptical in dorsal and ventral view, rounded in lateral view, protruding, its length (SL 7.8) longer than horizontal diameter of eye (EL 4.0); loreal region vertical and concave with rounded canthus rostralis; interorbital space flat, wider (IUE 4.2) than upper eyelid (UEW 2.8) and internarial distance (IN 3.8); distance between back of eye (IBE 10.1) 1.3 times the distance between front of eye (IFE 7.9); nostril oval, closer to tip of snout (NS 2.3) than eye (EN 4.0); tympanum (TYD 3.7) 93% of eye diameter (EL 4.0); tympanum-eye distance (TYE 1.0); pineal ocellus present, between anterior border of eyes; vomerine ridges present, bearing small teeth, with an angle of 45° to body axis, as close to choanae as to each other; tongue moderately large, emarginated. Forelimbs moderately short and strong; forelimb (FAL 8.5) shorter than hand length (HAL 12.6); fingers short, finger length formula I=II<IV<III; tips of all fingers with obtusely pointed discs, with lateroventral groove, moderately wide compared to finger width (FDI 1.0, FWI 0.6; FDII 1.1, FWII 0.4; FDIII 1.6, FWIII 0.6; FDIV 1.5, FWIV 0.7); dermal fringe present, subarticular tubercles prominent, oval, single, all present; two distinct oval palmar tubercles weakly developed; a distinct supernumerary tubercle on base of each finger. Hindlimbs relatively long and strong, thigh length (TL 19.8) shorter than shank (SHL 24.2), and foot (FOL 21.3); relative digit lengths I<II<III<V<IV; tips of all toes with small pointed discs possessing lateroventral grooves, rather wide compared to toe width (TDI 1.1, TWI 0.5; TDII 1.3, TWII 0.5; TDIII 1.2, TWIII 0.5; TDIV 1.3, TWIV 0.6; TDV 1.2, TWV 0.5); webbing present, moderate: I1-2II1-2+III1-3IV3-1V; weakly developed dermal ridge along toe V present; subarticular tubercles prominent, oval, all present; inner metatarsal tubercle distinct and moderately short, outer metatarsal tubercle rounded, prominent.
Skin of snout, between eyes, side of head and anterior part of dorsum granular; posterior part of back and upper part of flanks shagreened; lower part of flanks smooth; dorsolateral folds that extend from the posterior corner of the eye to the entire body length on both sides, moderately developed (Figs 5, 7d, f); dorsal part of forelimb smooth; thigh, tibia and tarsus granular with weakly developed warts in longitudinal lines bearing horny spinules; distinct rictal gland posterior to corner of mouth; flat indistinct humeral glands; ventral side of forearm having a straight line of granular projections from base of finger IV to elbow (Fig. 8d); weakly developed granular projections from base of toe V to knee (Fig. 8e).
Colour in preservation (Figs 7d-f). Dorsal parts greyish-brown with dark speckles; lower flanks light grey with black speckles; tympanic areas dark grey; upper lips with white stripe continuing through rictal gland to above arm insertion; dorsolateral folds light grey; forelimbs, dorsal surface of thighs, tibia and feet light greyish-brown with grey spots and weakly developed cross-bands, posterior part of thighs light grey with dark greyish-brown reticulations; throat and margin of throat, chest and belly greyish-white with black flecks; ventral parts of thighs, tibia and feet greyish-white with black spots; webbing dark grey with minute specks. Colour in life (Fig. 9b). Dorsum uniform greyish-brown with black specks; tympanum and surrounding areas light brown; upper lips with greyish-white stripe continuing through rictal gland to above arm insertion; iris reddish-brown with golden specks with dark patches on either side; flanks light yellowish-grey; limbs dorsally greyish-brown with light brown cross-bands; feet and webbing dark grey; throat and margin of throat, chest and belly greyish-white with prominent black flecks.
Variation. See Table 2 for morphometric data from 12 adult males and one adult female. BNHS 5815: posterior part of thigh light grey with dark brown reticulations; SDBDU 2011.540: side of head with horny spinules, posterior part of thigh light grey with light brown reticulations; BNHS 5822: anterior and posterior part of back prominently granular, loreal and tympanic region darker brown, posterior part of thigh light grey with dark brown reticulations; BNHS 5819: anterior and posterior part of back prominently granular with very prominent dark spots, posterior part of thigh light grey with dark brown reticulations; BNHS 5820: anterior and posterior part of back prominently granular with very prominent dark spots; BNHS 5817: posterior part of thigh without reticulation, with dark spots on light grey background; BNHS 5821, SDBDU 2006.4824 and SDBDU 2011.1169: anterior and posterior part of back prominently granular with very prominent dark spots, posterior part of thigh light grey with dark brown reticulations; BNHS 5821: ventral surface (lower part of belly) granular; BNHS 5818: anterior and posterior part of back prominently granular with very prominent dark spots; SDBDU 2011.265: anterior and posterior part of back prominently granular with very prominent dark spots, posterior parts of thigh with dark spots on light grey background rather than reticulations, anterior part of flanks granular, ventral side (lower part of belly) slightly granular.
Secondary sexual characters. Males: Single oval-shaped nuptial pad on finger I present, cream-coloured; two vocal sacs faintly visible externally on the posterior lateral side of the throat; humeral gland weakly developed, positioned laterally on the preaxial side of the upper forelimb. Females: ova white, pigmented on pole (diameter 1.2-1.7 mm, N = 20).
Etymology. This species is named after Dr. Don R. Church, in appreciation for his contribution to global amphibian conservation initiatives, especially for his tremendous support in formulating the Western Ghats Network of Protected Areas for Threatened Amphibians (WNPATA) for Western Ghats amphibian conservation. The species name doni is a noun in the genitive case.
Distribution. Hylarana doni is known only from the Western Ghats state of Kerala, with its distribution restricted to south of the Palghat Gap. The present study found this species in Palakkad dist. (Padagiri, Nelliyampathy; Kesavapara, Nelliyampathy; Parambikulam Tiger Reserve), Ernakulam dist. (Poomala and Thekkady), Pathanamthitta dist. (Gavi) and Thiruvananthapuram dist. (Chathankod and Palode) (Fig. 10, Table 1).
Habitat and natural history. The primary habitat of this species is broadly regarded as open secondary and primary forest. Specimens are reported from elevations of 116 to 1210 m asl. Hylarana doni was found to be relatively abundant at all of its collection localities. Animals are located in both disturbed agricultural areas (Poomala and Chathankod) and undisturbed forest habitats (Nelliyampathy, Parambikulam and Thekkady). BNHS 5818 and SDBDU 2011.540 were collected from leaf litter on the forest floor; BNHS 5821 and SDBDU 2011.265 from temporary water bodies near a small stream. The majority of specimens were found actively calling, and collected between 18:30-19:30 h.