Hylarana sreeni sp. nov.
Sreeni’s Golden-backed frog
Holotype. BNHS 5869, an adult male, Siruvani, Kuddam, Palakkad dist., Kerala state, India, collected by SDB and SG, 18 October 2011.
Paratypes. BNHS 5870, an adult male, Siruvani, Singappara, Palakkad dist., collected SDB and SG, 16 October 2011; BNHS 5871, an adult male, Kaikatti, Nelliyampathy, Palakkad dist., collected by SDB, 28 May 2010; BNHS 5872, an adult male, Thekkady, Idukki dist., collected by SDB and SG, 28 January 2012; BNHS 5873, an adult male, Glenback estate, Kiriparai, Kanyakumari dist., collected by SDB, 19 November 2008; BNHS 5874, an adult male, Pandimotta, Shendurney WLS, Thiruvananthapuram dist., collected by SDB and Systematics Lab team, 13 September 2011; BNHS 5875 an adult female, Siruvani, Singappara, Palakkad dist., collected by SDB and SG, 16 October 2011; BNHS 5876, an adult female, Parambikulam tiger reserve, Palakkad dist., collected by SDB and Systematics Lab team, 13 August 2011; BNHS 5877, an adult female, Gavi, Pathanamthitta dist., collected by SDB, 10 June 2006; BNHS 5878, an adult female, Chathankod, Thiruvananthapuram dist., collected by SDB and Systematics Lab team, 11 September 2011.
Referred specimens. SDBDU 2012.1831, an adult male, Thekkady, Idukki dist., collected by SDB and SG, 28 January 2012; SDBDU 2011.1257, an adult female, Siruvani, Singappara, Palakkad dist., collected by SDB and SG, 16 October 2011; SDBDU 2004.40352a, an adult female, Chathankod, Thiruvananthapuram dist., collected by SDB, 15 Januray 2004; SDBDU 2004.4553, a sub-adult female, Yercaud, Shevaroy hills, Salem dist., collected by SDB, 3 September 2004; SDBDU 2011.1041, a sub-adult male, Kadalar estate, Munnar, Idukki dist., collected by SDB and Systematics Lab team, 23 September 2011.
Comparison. Hylarana sreeni sp. nov. could not be confused with any species within the Hylarana flavescens group, by the suite of its adult size, male SVL 44.0-52.4 mm, N = 7, female SVL 64.8-80.1 mm, N = 6, sub-elliptical snout, granular dorsal skin and second toe webbing below the first tubercle on inside of toe II (Figs 12c, f, i, l, o, r). For detailed differences with Hylarana caesari, H. flavescens, H.indica, H. magna and H. montanus see ‘Comparison’ of those species.
Genetic divergence. Intraspecific genetic variation within populations of Hylarana sreeni was 0.8 ± 0.6% (range 0-1.5%, N = 12) for 16S, 2.3 ± 1.4% (range 0-3.6%, N = 12) for COI and 3.7 ± 2.2% (range 0-6.1%, N = 14) for Cytb (Table S2). Based on phylogenetic position, H. sreeni is closely related to the members of Hylarana flavescens group (Fig. 4). See Hylarana caesari, H. flavescens, H. indica, H. magna and H. montanus for comparison with those species.
Description of holotype (Figs 12p-r, 15h-j). Large-sized, moderately robust adult male (SVL 49.5). Head small (HW 15.9, HL 19.5, IFE 9.7, IBE 13.0), longer than wide, flat above; snout sub-elliptical in dorsal and ventral view, rounded in lateral view, slightly protruding, its length (SL 8.6) longer than horizontal diameter of eye (EL 5.7); loreal region vertical and concave with rounded canthus rostralis; interorbital space flat, wider (IUE 4.5) than upper eyelid (UEW 4.4) and narrower than internarial distance (IN 5.0); distance between back of eye (IBE 13.0) 1.3 times the distance between front of eye (IFE 9.7); nostril oval with flap of skin laterally, closer to tip of snout (NS 3.1) than eye (EN 4.7); tympanum (TYD 4.4) 77% of eye diameter (EL 5.7); tympanum-eye distance (TYE 1.5); pineal ocellus present, between anterior border of eye; vomerine ridge present, bearing small teeth, with an angle of 50° to body axis, as close to choanae as to each other; tongue moderately large, emarginated. Forelimbs moderately short and thin; forelimb (FAL 10.0) shorter than hand length (HAL 13.8); fingers long, finger length formula I=II<IV<III, finger tips with obtusely pointed discs and dorsoventrally compressed, with lateroventral grooves, moderately wide compared to finger width (FDI 0.9, FWI 0.5; FDII 1.1, FWII 0.4; FDIII 1.3, FWIII 0.4; FDIV 1.2, FWIV 0.5); dermal fringe present; subarticular tubercles prominent, oval, single, all present; two oval distinct palmar tubercles moderately developed; a distinct supernumerary tubercle at base of each finger. Hindlimbs relatively long and thin; thigh length (TL 25.2) shorter than shank (SHL 28.4), and subequal to foot (FOL 25.3); relative digit lengths I<II<III<V<IV; toe tips with obtusely pointed discs and dorsoventrally compressed, with lateroventral grooves, rather wide compared to toe width (TDI 1.2, TWI 0.7; TDII 1.4, TWII 0.6; TDIII 1.5, TWIII 0.7; TDIV 1.5, TWIV 0.6; TDV 1.2, TWV 0.6); webbing present, rather medium: I1-2II1-2+III1-2+IV2-1V; dermal ridge along toe V present; subarticular tubercles rather prominent, oval, all present; inner metatarsal tubercles distinct and rather short; outer metatarsal tubercles rounded, rather prominent.
Skin of snout and between eyes shagreened and sparsely granular; side of head shagreened to granular; upper eyelids granular; anterior and posterior part of dorsum granular with horny spinules; upper and lower parts of flanks rather shagreened to sparsely glandular; dorsolateral folds that extend from the posterior corner of the eye to the entire body length on both sides, well developed with horny spinules (Figs 5, 15h, j); dorsal part of forelimb shagreened, thigh sparsely granular, tibia and tarsus granular with well developed longitudinal horny spinules; anal region prominently granular; toe V with dermal fringe having granular projections from the base of V toe to knee; distinct rictal gland posterior to corner of mouth; distinct humeral glands; ventral part of throat smooth; anterior part of belly shagreened, posterior part of belly shagreened; posterior part of thigh granular.
Colour in preservation (Figs 15h-j). Dorsal surface greyish-brown, lower flank light brown; tympanic area light greyish-brown, tympanum light brown; upper lip with greyish-white stripe continuing through rictal gland to above arm insertion; forelimbs, dorsal parts of thigh, tibia and foot light greyish-brown with grey spots, anterior part of thigh reticulated with light greyish-brown patches on dark grey background; throat and margin of throat greyish-white; chest and belly greyish-white; ventral parts of thigh, tibia and foot light yellowish-brown; webbing dark grey with minute specks. Colour in life (Fig. 16d). Dorsal parts bronze coloured; lower flank light brown; tympanic area light greyish-brown, tympanum light brown; upper lip with yellowish-white stripe continuing through rictal gland to above arm insertion; forelimbs, dorsal parts of thigh, tibia and foot light brown with brown spots; anterior part of thigh reticulated with light yellowish-brown patches on light grey background; throat and margin of throat greyish-white; chest and belly greyish-white; ventral parts of thigh, tibia and foot greyish-white; webbing dark grey with minute specks.
Variation. See Table 2 for morphometric data from seven adult males and six adult females. BNHS 5874: dorsum dark grey with scattered feeble blackish-grey spots, prominent blackish-grey cross-bands on both fore and hind limbs; BNHS 5873: posterior surface of abdomen slightly granular and ventral surface of thighs, tibia and forelimb margins with prominent dark grey spots; SDBDU 2012.1831: sides of snout and loreal region with spinular projections; BNHS 5871: dorsum with blackish-grey spots, chest and belly dark greyish-brown with minute dark brown spots.
Secondary sexual characters. Males: Single oval shaped nuptial pad on finger I present, cream-coloured; two vocal sacs faintly visible externally as loose skin on the posterior lateral side of the throat; humeral gland weakly developed, positioned laterally on the preaxial side of the upper forelimb. Females (BNHS 5875): ova white, pigmented on pole (diameter 1.3-1.9 mm, N = 14).
Etymology. The species is named ‘sreeni’ after Dr. K. V. Sreenivasan, as a token of appreciation for him being a constant source of inspiration and support to SDB’s research over the past two decades.
Distribution. Hylarana sreeni is one of the more widely distributed Hylarana species in the southern Western Ghats states of Kerala and Tamil Nadu, and found at elevations between 100-1500 m asl. The present study reports this species from Chathankod, Pandimotta, Gavi, Thekkady, Munnar, Nelliyampathy, Parambikulam, and Siruvani, in Kerala, and Kiriparai in Tamil Nadu. This species was also found in the Shevaroy hills (Yercaud), in the Eastern Ghats (Fig. 14, Table 1).
Habitat and natural history. Hylarana sreeni was predominantly found in primary and secondary forest habitats, in perennial fast flowing streams, usually perched on rocks, or on the banks of the streams. During the breeding season, egg laying was observed in shallow peripheral parts of the streams.
Hylarana temporalis group. This group can be distinguished from other peninsular Indian-Sri Lankan Hylarana groups by the following suite of characters: small to large-sized adult (male, SVL 30-69 mm; female, SVL 42-80 mm), body slender to robust; dorsolateral folds moderately or well developed (Fig. 5); finger and toes dorsoventrally compressed with obtusely pointed discs (Fig. 6); fourth toe webbing extends beyond the second subarticular tubercle on the outside of toe IV; endemic to Sri Lanka. In a phylogenetic framework, Hylarana temporalis group can be characterised as the most inclusive clade that contains a Sri Lankan radiation (Hylarana serendipi sp. nov. + H. temporalis) and none of the Indian radiations (Fig. 4).