Contributions to Zoology, 83 (4) – 2014S.D. Biju; Sonali Garg; Stephen Mahony; Nayana Wijayathilaka; Gayani Senevirathne; Madhava Meegaskumbura: DNA barcoding, phylogeny and systematics of Golden-backed frogs (Hylarana, Ranidae) of the Western Ghats-Sri Lanka biodiversity hotspot, with the description of seven new species

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Hylarana intermedius (Rao, 1937)

Rao’s intermediate Golden-backed frog

(Figs 7g-i, 8g-i, 9d-g, 10; Tables 1-2)

Original name and description. Rana (Hylorana) intermedius Rao, 1937. On some new forms of Batrachia from s. India, Proceedings of Indian Academy of Science, Series B, 6: 394. Neotype. By present designation, BNHS 5823, an adult male, SVL 39.2 mm, collected by SDB and SG, 1 October 2012 from Sakleshpur. Type locality. Sakleshpur, Hassan dist., ‘Mysore’ (current Karnataka) state, India. Current status of specific name. Valid name, as Hylarana intermedius (Rao, 1937).

Referred specimens. SDBDU 2012.2209, an adult male, Sakleshpur, Hassan dist., collected by SDB and SG, 1 October 2012; BNHS 5824, an adult male, Bhagamandala, Kodagu dist., collected by SDB and team, 13 June 2011; BNHS 5825, an adult male, Kachigebailu, Shimoga dist., 10 June 2011; BNHS 5826-5828 and SDBDU 2003.40190, four adult males, Jog falls, Shimoga dist., collected by SDB, 26 June 2003; BNHS 5829, an adult male, Adyar, Mangalore, Dakshin Kannada dist., collected by SDB and team, 24 October 2011; BNHS 5830 and SDBDU 2012.2224, two adult males, Madikeri, Kodagu dist., collected by SDB and SG, 2 October 2012; BNHS 5831, an adult male, Wattakolli, Coorg, Kodagu dist., collected by SDB and team, 15 June 2011; BNHS 5832, an adult male, Kalpetta, Wayanad dist., collected by SDB, 17 August 2007; BNHS 5833-5835 and SDBDU 2002.580, four adult females, Kalpetta, Wayanad dist., collected by SDB, 20 July 2002; BNHS 5836, an adult male, Kakkayam, Kozhikode dist., collected by SDB and Systematics Lab team, 25 May 2010; SDBDU 2011.203, a sub-adult, Bhagamandala, Kodagu dist., collected by SDB and team, 13 June 2011; SDBDU 2011.216, a sub-adult, Thalakaveri, Kodagu dist., collected by SDB and team, 14 June 2011; SDBDU 2011.1407, sub-adult, Adyar, Mangalore, Dakshin Kannada dist., collected by SDB and team, 24 October 2011.

Comments. Rao (1937) described Rana (Hylorana) intermedius from ‘Saklespur, Hassan District, Mysore State’ based on one specimen ‘(total length 43 mm)’, deposited in Central College, Bangalore. The original name bearing type of this species is lost (Dubois, 1984; SDB personal observation). This nominal taxon was considered a junior subjective synonym of H. temporalis by Dubois (1992); a decision concurred by subsequent authors (e.g. Dutta, 1997; Dutta and Manamendra-Arachchi, 1996). Rao (1937) mentions ‘the size and proportions of the head’ and ‘relative size of the tympanum and the eye’ as a justification to consider this taxa as a new species, without any comparison with other known species. Our collections from the type locality correspond to the general body size and degree of webbing between the toes of Rana (Hylorana) intermedius, as described in the original description (Rao, 1937, ‘figures 3 and 3a’, plate XXII). The primary inconsistency between recent collections and the original description was in the relative measurements, but we consider these differences to be a matter of size variation. For nomenclatural stability, we formally designate BNHS 5823 as the neotype for this taxon and elevate Hylarana intermedius to the status of a valid species. 

Comparison. Hylarana intermedius could be confused with Hylarana aurantiaca, Hylarana doni sp. nov. and Hylarana urbis sp. nov. in the Hylarana aurantiaca group, due to its small adult size. However H. intermedius differs from all other members in this group by its shank equal to foot length, male SHL 17.9 ± 0.9 mm, FOL 17.9 ± 0.9 mm, N = 14 (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. shorter, SHL 15.9 ± 1.0 mm, FOL 16.3 ± 1.6 mm, N = 5, H. urbis). More specifically differs from H. doni by its small adult male snout-vent size, SVL 33.0-41.6 mm, N = 14 (vs. SVL 38.0-43.1 mm, N = 12), fingers and toes thin (Figs 8d-e, g-h) with weakly developed subarticular tubercles (vs. thick with well developed subarticular tubercles), dorsal skin shagreened (vs. granular), dorsolateral folds weakly developed (vs. moderately developed). Furthermore, H. intermedius differs from H. doni by its webbing extending beyond the second subarticular tubercle on the outside of toe IV (vs. up to the second subarticular tubercle), ventral side of forearm without granular projections (vs. ventral side of forearm, having a straight line of granular projections from the base of finger IV to the elbow); differs from H. urbis by its relatively more webbing I1-2II1-2III1-3IV2⅔-1V (vs. less I2--2+II1¾-2¾III2--3IV3-1¾ V) (Figs 8h-I, k-l).

Genetic divergence. Intraspecific genetic variation within Hylarana intermedius was 0.2 ± 0.1% (range 0-0.4%, N = 9) for 16S, 0.4 ± 0.3% (range 0-0.7%, N = 9) for COI and 1.7 ± 1.8% (range 0-5.3%, N = 9) for Cytb. Based on phylogenetic position, H. intermedius is closely related to the members of Hylarana aurantiaca group (Fig. 4); differs from H. urbis by mean genetic divergence of 3.8 ± 0.1% (range 3.7-3.9%, N = 27) for 16S, 8.9 ± 0.2% (range 8.6-9.2%, N = 27) for COI, and 10.3 ± 1.3% (range 9.3-13.8%, N = 27) for Cytb (Tables S2-S3). See Hylarana aurantiaca and H. doni for comparison with those species.

Description of neotype (Figs 7g-i, 8g-i). Small-sized, slender adult female (SVL 39.2). Head small (HW 10.6, HL 14.6, IFE 6.7, IBE 8.9), longer than wide, slightly concave above; snout subovoid in dorsal and ventral view, rounded in lateral view, protruding, its length (SL 6.5) longer than horizontal diameter of eye (EL 3.8); loreal region acute and concave with rounded canthus rostralis; interorbital space slightly concave, wider (IUE 3.5) than upper eyelid (UEW 2.6) and equal to internarial distance (IN 3.5); nostril oval with flap of skin laterally, closer to tip of snout (NS 1.8) than eye (EN 3.5); tympanum (TYD 3.5) 92% of eye diameter (EL 3.8); vomerine ridge present but weak, bearing numerous small teeth, with an angle of 40° to body axis, closer to choanae than each other, shorter than the distance between them; tongue moderately large, emarginated, bearing no medium lingual process. Forelimbs moderately long and thin; forelimb (FAL 6.8) shorter than hand length (HAL 11.5); 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 0.7, FWI 0.4; FDII 0.8, FWII 0.5; FDIII 1.3, FWIII 0.5; FDIV 1.2, FWIV 0.4); 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 thick, thigh length (TL 16.3) shorter than shank (SHL 19.7), and foot (FOL 19.8); 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 0.8, TWI 0.3; TDII 1.0, TWII 0.5; TDIII 1.0, TWIII 0.5; TDIV 1.0, TWIV 0.4; TDV 0.8, TWV 0.4); webbing present, moderate: I1-2II1-2III1-3IV22/3 -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 sparsely granular; posterior part of back, upper and lower part of flanks shagreened; dorsolateral folds that extend from the posterior corner of the eye to the entire body length on both sides, moderately developed (Figs 5, 7g, i); dorsal part of forelimb shagreened; thigh shagreened to sparsely granular; tibia and tarsus sparsely granular with weakly developed warts in longitudinal lines; distinct rictal gland posterior to corner of mouth; flat indistinct humeral glands.

Colour in preservation (Figs 7g-i). Dorsal parts greyish-brown with light brown irregular spots, lower flank light grey; tympanic area dark brownish-grey; upper lip with white stripe continuing through rictal gland to above arm insertion; dorsolateral folds light grey; forelimbs, dorsal part of thigh, shank and foot light grey with irregular light brown spots; throat and margin of throat greyish-white; chest and belly greyish-white; ventral parts of thigh, tibia and foot greyish-white with minute black spots; webbing light grey with minute specks. Colour in life (Fig. 9d). Dorsal parts light golden brown with irregular light brown spots; lower flank greyish-brown with black speckles; tympanic area reddish-brown; upper lip with light yellow stripe continuing through rictal gland to above arm insertion; dorsolateral folds light brown; forelimbs, dorsal part of thigh, shank and foot light brown with grey spots; margin of throat white; chest and belly off-white, ventral parts of thigh, tibia and foot greyish-white with minute black spots; webbing dark grey with minute specks; iris reddish-brown.

Variation. See Table 5 for morphometric data from 14 adult males and four females. BNHS 5836: with more prominently granular dorsum; BNHS 5831, BNHS 5826-5827: dorsum uniform light brown without spots.

Secondary sexual characters. Males: Single oval-shaped nuptial pad on finger I present, greyish-white coloured; vocal sac not visible externally on lower jaw (internal vocal slits present); humeral gland weakly developed, positioned laterally on the preaxial side of the upper forelimb. Females (BNHS 5833): ova white, pigmented on pole (diameter 0.7-1.0 mm, N = 20).

Distribution. This species is endemic to the Western Ghats and its distribution is restricted to north of the Palghat Gap. It is widely distributed in Karnataka and adjoining regions of Kerala, predominently at elevations between 600-1183 m asl, but also as low as 8 m asl at Adyar (Mangalore). In the present study, we collected this species from Sakleshpur (Hassan dist.), Bhagamandala, Madikeri and Wattakolli (Kodagu dist.), Kachigebailu and Jog falls (Shimoga dist.) and in lowland areas of Adyar, Mangalore (Dakshin Kannada dist.) in Karnataka state, and Kalpetta (Wayanad dist.) and Kakkayam (Kozhikode dist.) in the northern parts of Kerala state. (Fig. 10, Table 1).

Habitat and natural history. This species was collected either from disturbed habitats adjacent to secondary forest (Kachgebailu, Jog falls, Wattakolli, Kalpetta and Kakkayam), or wayside temporary ponds surrounded by vegetation (Saklespur, Madikeri and Adyar, Mangalore). Animals were found both in temporary and permanent water bodies but none were found in fast flowing streams. Specimens from the type locality (BNHS 5823 and SDBDU 2012.2209) were collected from vegetation surrounding a water body in a cultivated field. Kalpetta populations were found either in cultivated fields (BNHS 5832 and SDBDU 2002.580), or secondary forest near urban areas (BNHS 5833-5835). BNHS 5831 and BNHS 5835 were collected from leaves up to one meter above the ground, near a water body. During daytime animals were found on leaf litter close to water bodies. BNHS 5827-5828 were collected from a bush overhanging a stream, at a height of ca. 1.5 m.