Raorchestes aureus, Vijayakumar, S. P., Dinesh, K. P., Prabhu, Mrugank V. & Shanker, Kartik, 2014

Vijayakumar, S. P., Dinesh, K. P., Prabhu, Mrugank V. & Shanker, Kartik, 2014, Lineage delimitation and description of nine new species of bush frogs (Anura: Raorchestes, Rhacophoridae) from the Western Ghats Escarpment, Zootaxa 3893 (4), pp. 451-488 : 464-466

2. Raorchestes aureus sp. nov.

( Figures 2 , 3 & 5 ; Tables 2 & 3)

Holotype: ZSI/ WGRC /V/A/867 ( CESF 1165), an adult male (SVL 24.8 mm), collected by S.P. Vijayakumar and Mrugank V. Prabhu in July 2010 from a high elevation site (10.9452 N, 76.6446 E) in Elivalmalai Massif ( Fig 1 ), Western Ghats, Peninsular India.

Paratype: ZSI/ WGRC /V/A/868 ( CESF 1164), an adult female (SVL 28.3), collected by S.P. Vijayakumar and Mrugank V. Prabhu in July 2010 from a high elevation site (10.9452 N, 76.6446 E) in Elivalmalai Massif ( Fig 1 ), Western Ghats, Peninsular India.

Lineage diagnosis. Raorchestes aureus sp. nov. can be diagnosed as a deeply divergent (16S—7.3%) lineage nested within a larger clade N ( Fig 3 ). The lineage is isolated on the high elevations of Elivalmalai Massif ( Fig 1 & 2 ). Morphologically, it shows strong signatures of divergence from other similar relatives within clade N (see below). We use all the above criteria, genetic divergence, geographical range and morphology to diagnose this lineage. The relatives that potentially overlap in morphology and hence could be confused with this lineage within the clade N are discussed below.

Field diagnosis. Morphology. Raorchestes aureus sp. nov. could be confused with R. chromasynchysi which occurs in sympatry (see remarks). However, the new species can be differentiated based on the shorter thigh length, TL/SVL=0.45 (0.44–0.45, n=4) (vs. TL/SVL=0.52 (0.50–0.54, n=3) in R. chromasynchysi ); shorter tibia length, ShL/SVL=0.46 (0.45–0.47, n=4) (vs. ShL/SVL=0.51 (0.50–0.51, n=3) in R. chromasynchysi ); in having a distinct golden iris (vs. silvery to light brown in R. chromasynchysi ); dorsal coloration shades of brown (vs. very variable from shades of brown to green in R. chromasynchysi ); anterior and posterior region of thigh (femur) characterized by distinct or faint cross bar with alternating darker and lighter shades of brown (vs. plain coloration on the posterior thigh and dark coloration with yellow blotches on the anterior thigh in R. chromasynchysi ); lateral sides of irregular mottling of brown/yellow and green extending from groin to base of supratympanic fold (vs. distinct separation of dorsal and ventral coloration without any such mottling).

Geography. Current data suggests a narrow restricted range to the high elevation of Elivalmalai Massif in the Western Ghats (see natural history and distribution for details).

Description of holotype (all measurements in mm). A small sized bush frog (SVL = 24.8 mm), width of head broader than head length (HW = 10.3 mm; HL = 8.3 mm), flat dorsally; snout acutely pointed in total profile, slightly protruding beyond mouth. Snout length is sub equal to diameter of eye (SL = 3.4 mm, EL = 3.7 mm). Canthus rostralis angular, loreal region slightly concave. Interorbital space (IUE = 2.9 mm) flat and sub equal to upper eyelid (UEW = 2.6 mm). Interorbital space between posterior margins of the eyes 1.8 times that of anterior margins (IFE = 5.0, IBE = 9.1 mm). Nostrils oval, nearer to tip of snout. Weak symphysial knob. Pupil horizontal. Tympanum distinct, rounded, small, barely visible behind the eye. Tongue bifid, granular with a papilla. Supratympanic fold from behind eye to shoulder.

Relative length of fingers I<II<IV<III, finger tips with well developed disks (fd3 = 1.4 mm; fw3 = 0.7) with distinct circum–marginal grooves, fingers with dermal fringes on both sides. Webbing on palm absent, subarticular tubercles distinct, rounded and pre-pollex tubercle oval, distinct. Supernumerary tubercles absent.

Hind limb long, heels overlap when folded at right angles to the body. Thigh/Femur (TL = 11.2 mm), sub equal to Shank/Tibia (ShL = 12.1 mm); longer than foot (FOL = 9.7 mm) and less than heel to tip of fourth toe (TFOL = 16.0 mm). Relative toe length I<II<III<V<IV, webbing poor, web formula (I 1- 1 II 1- 2 III 1-2½ IV 2 ½- 1 V). Tibiotarsal articulation reaches anterior corner of eye. Outer metatarsal tubercle, supernumerary tubercles and tarsal tubercle absent.

Color in life. Limbs faintly cross-barred, pattern extending towards the anterior and posterior parts of the thigh. Lateral sides characterized by irregular mottling of yellow and light green extending from groin to base of supratympanic fold. Ventral parts of head, body, hand and foot mottled, but more pronounced at the region of belly and throat. Iris distinct golden with brown edged coarse speckles around the pupil, visible even in the preserved specimens.

Etymology. The species is named after the consistent golden iris coloration (Latin: aureus = golden).

Natural history and distribution. All the individuals were collected from forest edges in a grassland site and all males located were found calling at the ground level. It appears to be a range restricted species, recorded from a single high elevation (1524 m) site in Elivalmalai Massif ( Fig 1 & 2 ). The elevational range within Elivalmalai needs additional field sampling.

Remarks. R. chromasynchysi was known only from the type locality ( Biju and Bossuyt 2009) and a recent record from north of its type locality ( Dinesh and Radhakrishnan, 2012). We have uncovered multiple potential lineages across various Massifs and hill ranges in the central Western Ghats (see above under sub-clade composition). For the above quantitative comparison, we have used individuals from a shallow divergent lineage that overlap with the range of Raorchestes aureus sp. nov.

Figures

FIGURE 2. Geographic distribution of new species of bush frogs (Raorchestes) from Western Ghats. Orange filled circles

FIGURE 5. Raorchestes aureus sp. nov. (a) profile in life; (b) eye profile in life; (c) dorsal profile of holotype; (d) ventral profile of holotype.

FIGURE 3. A maximum likelihood tree for bush frogs, and in the Western Ghats, based on three MtDNA genes: 16 S, Cytb and ND 1. The lineages described are marked in red. Sub-clades are named on the right.

FIGURE 1. A map of the Western Ghats showing the major physiographic features referred to in the text.