Hylarana urbis sp. nov.
Urban Golden-backed frog
Holotype. BNHS 5837, an adult male, Kadavanthra, Ernakulam dist., Kerala state, India, collected by SDB and SG, 12 April 2012.
Paratypes. BNHS 5838, an adult male and BNHS 5839, an adult female, collected along with holotype; BNHS 5840, an adult male, Tripunithura, Ernakulam dist., collected by SDB and team, 27 April 2012; BNHS 5841, an adult male, Meladoor, Thrissur dist., collected by SDB, 7 July 2003.
Referred specimens. SDBDU 2003.40230, an adult male, Meladoor, Thrissur dist., collected by SDB, 7 July 2003; SDBDU 2012.2039, a sub-adult, Kadakkattupara, Malappuram dist., collected by SDB and SG, 25 April 2012.
Comparison. Hylarana urbis sp. nov. could be confused with Hylarana aurantiaca, Hylarana intermedius and Hylarana doni sp. nov. within the Hylarana aurantiaca group due to its small adult size. However, H. urbis differs from H. doni and H. intermedius by the combination of small adult male snout-vent size, SVL 30.1-34.3 mm, N = 5 (vs. SVL 38.0-34.1 mm, N = 12, H. doni; SVL 33.0-41.6 mm, N = 14, H. intermedius) and weakly developed dorsolateral fold (vs. moderately developed in both species) (Figs 7d, g, j); differs from all other members of the Hylarana aurantiaca group by its shank shorter than foot length, male SHL 15.9 ± 1.0 mm, FOL 16.3 ± 1.6 mm, N = 5 (vs. longer, SHL 14.7 ± 0.6 mm, FOL 14.2 ± 0.5 mm, N = 9, H. aurantiaca; SHL 21.7 ± 1.3 mm, FOL 19.8 ± 1.0 mm, N = 12, H. doni; vs. equal, SHL 17.9 ± 0.9 mm, FOL 17.9 ± 0.9 mm, N = 14, H. intermedius) and relatively less webbing between toes I2--2+II13/4 -23/4 III2--3IV3-13/4 V (vs. more in other three species, I11/3 -2II1+-2+III11/2 -3IV21/2 -11/4 V in H. aurantiaca, I1-2II1-2+III1-3IV3-1V in H. doni, I1-2II1-2III1-3IV22/3 -1V in H. intermedius) (Figs 8b-c, e-f, h-i, k-l). For more differences with Hylarana aurantiaca, H. doni, H. intermedius see ‘Comparison’ of those species.
Genetic divergence. Intraspecific genetic variation within Hylarana urbis was zero (N = 3) for 16S, 0.1 ± 0.1% (range 0-0.2%, N = 3) for COI, and 0.4 ± 0.3% (range 0-0.6%, N = 3) for Cytb (Tables S2). Based on phylogenetic position, H. urbis is a member of the Hylarana aurantiaca group (Fig. 4). See Hylarana aurantiaca, H. doni and H. intermedius for comparison with those species.
Description of holotype (Figs 7j-l, 8j-l). Small-sized, moderately slender adult male, (SVL 30.1). Head small (HW 8.5, HL 10.3, IFE 5.6, IBE 7.3), longer than wide, flat above; snout sub-elliptical in dorsal and ventral view, rounded in lateral view, protruding, its length (SL 5.6) longer than horizontal diameter of eye (EL 3.2); loreal region vertical and flat with rounded canthus rostralis; interorbital space flat, wider (IUE 2.8) than upper eyelid (UEW 1.9) and subequal to internarial distance (IN 3.0); distance between front of eye (IFE 5.6) 1.3 times of distance between back of eye (IBE 7.3); nostril oval, closer to tip of snout (NS 1.4) than eye (EN 2.6); tympanum (TYD 2.5) 78% of eye diameter (EL 3.2); tympanum-eye distance (TYE 0.9); pineal ocellus present, between anterior border of eyes; vomerine ridge 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 thin; forelimb (FAL 5.3) shorter than hand length (HAL 8.7); 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 0.5, FWI 0.4; FDII 0.7, FWII 0.4; FDIII 0.8, FWIII 0.3; FDIV 0.9, FWIV 0.6); subarticular tubercles prominent, oval, single, all present; prepollex distinct, oval; two oval distinct palmar tubercles; a distinct supernumerary tubercle on base of each finger. Hindlimbs relatively long and thin; thigh length (TL 13.0) shorter than shank (SHL 15.9), and foot (FOL 16.1); relative digit lengths I<II<III<V<IV; tips of all toes with small obtusely pointed discs possessing lateroventral grooves, rather wide compared to toe width (TDI 0.3, TWI 0.2; TDII 0.7, TWII 0.4; TDIII 0.7, TWIII 0.3; TDIV 0.7, TWIV 0.3; TDV 10.6, TWV 0.3); webbing present, moderate: I2--2+II13/4 -23/4 III2--3IV3-13/4 V; 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 shagreened, posterior part of back and upper part of flanks shagreened with scattered glandular projections; lower part of flanks rather smooth; dorsolateral folds that extend from the posterior corner of the eye to the entire body length on both sides, weakly developed (Figs 5, 7j, l); dorsal part of forelimb without smooth; thigh, tibia and tarsus shagreened with scattered glandular projections; distinct rictal gland posterior to corner of mouth (Fig. 7l).
Colour in preservation (Figs 7j-l). Dorsal parts light grey, lower flanks light grey with black speckles; tympanic area light 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 grey with minute black spots and weakly formed cross-bands; throat and margin of throat greyish-white with black flecks; chest and belly greyish-white; ventral parts of thighs, tibia and feet greyish-white with black spots; webbing dark grey with minute specks. Colour in life (Fig. 9h). Dorsum uniform greyish-brown; tympanum and surrounding areas dark brown; upper lips with white stripe continuing through rictal gland to above arm insertion; iris reddish-brown in lower half and golden brown in upper half; flanks light grey; limbs dorsally light greyish-brown with light brown cross-bands; throat and margin of throat, chest and belly greyish-white with minute black spots; feet and webbing dark grey.
Variation. See Table 2 for morphometric data from five adult males and an adult female. BNHS 5838: dorsum blackish-brown in preservation (brownish-black in life).
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 (BNHS 5839): ova immature.
Etymology. The species epithet is a noun in apposition, therefore invariable, derived from a Latin phrase ‘urbis’ meaning urban or city, referring to the species inhabiting mainly urban areas.
Distribution. This species is known only from Kadavanthra and Tripunithura (Ernakulam dist.), Kadakkattupara (Malappuram dist.), and Meladoor (Thrissur dist.) in Kerala state, southern Western Ghats (Fig. 10, Table 1).
Habitat and natural history. The primary habitat of this species is broadly regarded as open wayside water bodies in urban areas, below 150 m asl. The holotype and paratypes were found near an open pond with overhanging vegetation; BNHS 5841 and SDBDU 2003.40230 were found calling from vegetation close to paddy fields at around 17:30 h.
Hylarana flavescens group. This group can be distinguished by the following suite of characters: medium to large-sized adult (male, SVL 43-85 mm; female, SVL 58-92 mm), body robust; dorsolateral folds well developed (Fig. 5); finger and toe discs dorsoventrally compressed and obtusely pointed (Fig. 6); fourth toe webbing extends up to the first subarticular tubercle on the outside; endemic to the Western Ghats. In a phylogenetic framework, Hylarana flavescens group can be characterised as the most inclusive clade that contains a Western Ghats radiation (Hylarana caesari sp. nov., H. flavescens, Hylarana indica sp. nov., Hylarana magna sp. nov., H. montanus and Hylarana sreeni sp. nov.), but none of the other Western Ghats or Sri Lankan clades of Hylarana (Fig. 4).