Hylarana magna sp. nov.
Large Golden-backed frog
Holotype. BNHS 5857, an adult male, Pandimotta, Shendurney WLS, Thiruvananthapuram dist., Kerala state, India, collected by SDB and Systematics Lab team, 13 September 2011.
Paratypes. BNHS 5858-5861, four adult females, Athirimala, Thiruvananthapuram dist., Kerala State, collected by SDB, 16 May 2002.
Referred specimens. SDBDU 2002.2050, a sub-adult female, collected by SDB, 30 August 2002, and SDBDU 2008.1929, a sub-adult female, collected by SDB, 16 November 2008, from Kakkachi, Tirunelveli dist.; SDBDU 2012.899, a sub-adult male, from Pandipath, Thiruvananthapuram dist., collected by SDB and team, 21 September 2012.
Comparison. Hylarana magna sp. nov. could not be confused with any taxa within the Hylarana flavescens group, due to its large adult size, male SVL 84.5 mm, N = 1; female SVL 78.7-91.8 mm, N = 4 (vs. male SVL 43.2-50.1 mm, N = 5, female SVL 58.0-59.7 mm, N = 2 in H. caesari; male SVL 45.2-59.5 mm, N = 4, female SVL 75.5 mm, N = 1 in H. flavescens; male SVL 45.8-58.6 mm, N = 10, female SVL 66.0-74.3 mm, N = 3 in H. indica; male SVL 54.0-65.0 mm, N = 8, female SVL 65.6-74.5 mm, N = 3 in H. montanus; male SVL 44.0-52.4 mm, N = 7, female SVL 64.8-80.1 mm, N = 6 in H. sreeni), snout nearly truncate in dorsal and ventral view (vs. sub-elliptically pointed in H. caesari, rounded in H. flavescens, sub-elliptical in H. indica and H. sreeni, rounded to truncate in H. montanus) (Figs 11a-b, d-e, g-h, j-k, 15a-b, h-i) and shagreened dorsal skin (vs. granular in H. caesari and H. indica, shagreened to sparsely granular in H. flavescens, H. montanus and H. sreeni); more specifically differs from H. montanus by its thigh shorter to foot length, TL 41.0 mm, FOL 42.7 mm, male, N = 1 (vs. equal, TL 30.0 ± 1.6 mm, FOL 30.0 ± 1.6 mm, male, N = 8); differs from H. sreeni by its second toe webbing above the first subarticular tubercle on the inside (vs. just below the first subartcluar tubercle), interorbital space wider than the upper eyelid width, IUE 9.7 mm, UEW 6.1 mm, male, N = 1 (vs. subequal, IUE 4.1 ± 0.5 mm, UEW 4.0 ± 0.4 mm, N = 7). For differences with Hylarana caesari, H. flavescens and H. indica see ‘Comparison’ of those species.
Genetic divergence. Intraspecific genetic variation within populations of Hylarana magna was 0.2 ± 0.1% (range 0-0.4%, N = 4) for 16S, zero (N = 4) for COI and 0.7 ± 0.8% (range 0-2.1%, N = 5) for Cytb. Based on phylogenetic position, H. magna is closely related to the members of Hylarana flavescens group (Fig. 4); differs from H. montanus by mean interspecific divergence of 7.3 ± 0.3% (range 6.9-7.8%, N = 28) for 16S, 10.7 ± 1.3% (range 9.7-13.8%, N = 28) for COI and 16.3 ± 0.7% (range 15.5-17.8%, N = 40) for Cytb; differs from H. sreeni by mean interspecific divergence of 7.0 ± 0.1% (range 6.7-7.2%, N = 48) for 16S, 12.0 ± 0.3% (range 11.6-12.5%, N = 48) for COI and 18.1 ± 0.9% (range 16.4-20.4%, N = 70) for Cytb (Tables S2-S3). See Hylarana caesari, H. flavescens and H. indica for comparison with those species.
Description of holotype (Figs 11j-l, 12j-l). Large-sized, robust species, adult male (SVL 84.5). Head moderately large (HW 30.1, HL 32.8, IFE 15.1, IBE 21.9), longer than wide, flat above; snout nearly truncate in dorsal, ventral and lateral view, protruding, its length (SL 12.4) longer than horizontal diameter of eye (EL 8.1); loreal region acute and concave, canthus rostralis rounded; interorbital space flat, wider (IUE 9.7) than upper eyelid (UEW 6.1) and internarial distance (IN 8.2); distance between back of eyes (IBE 21.9) slightly more than 1.4 times the distance between front of eyes (IFE 15.1); nostril closer to tip of snout (NS 3.7) than eye (EN 7.3); tympanum (TYD 6.5) 80% of eye diameter (EL 8.1); tympanum-eye distance (TYE 4.4); pineal ocellus present, between anterior border of eyes; vomerine ridges present, bearing numerous small teeth, with an angle of 45° to body axis, as close to choanae as to each other; tongue moderately large, emarginated. Forelimbs short and thick; forelimb (FAL 16.1) shorter than hand length (HAL 22.5); fingers long, finger length formula II<I<IV<III, finger tips with obtusely pointed discs and dorsoventrally compressed, with lateroventral groove, moderately wide compared to finger width (FDI 2.7, FWI 1.0; FDII 2.4, FWII 10.9; FDIII 3.0, FWIII 0.9; FDIV 3.0, FWIV 1.0); dermal fringe present; subarticular tubercles rather prominent, oval, single, all present; two oval distinct palmar tubercles weakly developed; distinct supernumerary tubercles present on base of each finger. Hindlimbs relatively long; thigh length (TL 41.0) shorter than shank (SHL 43.5), and foot (FOL 42.7); 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 2.6, TWI 0.7; TDII 2.7, TWII 0.9; TDIII 2.9, TWIII 0.9; TDIV 3.1, TWIV 0.9; TDV 2.7, TWV 0.1); webbing present, rather medium: I1-11/2 II1-2III1-2IV2--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; supernumerary tubercles absent; tarsal tubercles absent.
Skin of snout, between eyes, sides of head and anterior part of dorsum shagreened; posterior part of back and upper part of flanks shagreened; dorsolateral folds that extend from posterior corner of eye to the entire body length on both sides, well developed (Figs 5, 11j, l); dorsal part of forelimbs without glandular warts; thighs, tibia and tarsus with weakly developed glandular warts; distinct rictal gland posterior to corner of mouth; flat weakly developed humeral glands; ventral parts of throat and belly smooth; anterior and posterior part of belly shagreened; posterior part of thigh granular.
Colour in preservation (Figs 11j-l). Dorsal surfaces greyish-brown with scattered blackish spots; lower flanks light grey with black speckles; tympanic area dark grey; upper lip with white stripe continuing through rictal gland to above arm insertion; dorsolateral folds light grey; forelimbs, dorsal parts of thigh, tibia and foot light greyish-brown with grey spots, cross-bands are weakly formed; throat and margin of throat greyish-white with black flecks; chest and belly greyish-white; ventral surface of thighs, tibia and feet greyish-white with black spots; webbing dark grey with minute specks. Colour in life (Figs 13f-g). Dorsal parts light brown with grey spots; lower flanks bronze coloured; tympanic area reddish-grey; upper lip with white stripe continuing through rictal gland to above arm insertion; forelimbs, dorsal surface of thighs, tibia and feet light brown with grey spots, cross-bands are weakly formed; throat and margin of throat white with black flecks; chest and belly off-white; ventral surface of thighs, tibia and feet grey-white with black spots; webbing dark grey with minute specks; iris lower half dark brown and upper half golden brown.
Variation. See Table 2 for morphometric data from one adult male and four adult females. BNHS 5858: dorsal skin shagreened and sparsely granular, throat and chest with minute specks, posterior surface of thighs mottled; BNHS 5860: ventral surface of thighs sparsely granular.
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 5859): ova white, pigmented on pole (diameter 1.7-2.1 mm, N = 30).
Etymology. The species epithet is derived from the Latin word ‘magna’ meaning ‘large’, which refers to the large body size of the new species, when compared with congeners from the Western Ghats-Sri Lanka biodiversity hotspot.
Distribution. This species is known only from four localities in the Agasthyamala hills (Pandimotta, Athirimala, Attyar, Pandipath) in the southern Western Ghats of Kerala state, and adjoining regions (Kakkachi) of Tamil Nadu state, between 600-1425 m asl. The distribution of H. magna is restricted to south of the Palghat Gap (Fig. 14, Table 1).
Habitat and natural history. This species was only found in evergreen forests. BNHS 5857 and SDBDU 2012.899: collected from the banks of a flowing stream in a closed canopy forest; BNHS 5858-5861: collected from emergent boulders in a fast flowing stream inside primary forest. During the dry season this species was commonly observed on stream banks, or amongst vegetation near forest streams, whereas during the monsoon (June-September), males were located on emergent boulders in these streams. After sunset they continued to call until around 21:00 h.