Raorchestes leucolatus, 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 : 477-479

8. Raorchestes leucolatus sp. nov.

( Figures 2 , 3 & 12 ; Tables 2 & 3)

Holotype: ZSI/ WGRC /V/A/879 ( CESF 1146), an adult male (SVL 16.9 mm), collected by S.P. Vijayakumar, Mrugank V. Prabhu and and Mayavan in July 2010 from a wet evergreen forest site (10.9731 N, 76.6289 E), Elivalmalai Massif ( Fig 1 ), Peninsular India.

Paratype: ZSI/ WGRC /V/A/880 ( CESF 1147), an adult male (SVL 17.1 mm), collected by S.P. Vijayakumar, Mrugank V. Prabhu and Mayavan in July 2010 from a wet evergreen forest site (10.9731 N, 76.6289 E), Elivalmalai Massif ( Fig 1 ), Western Ghats, Peninsular India.

Lineage diagnosis. Raorchestes leucolatus sp. nov. can be diagnosed by its phylogenetic position within the Bombayensis clade ( Fig 3 ) and exhibits moderate levels (16S—2.9%) of divergence from its closest relative R. tuberohumerus . It also shows strong differences in morphology ( Fig 12 a,d,e,f). The lineage is diagnosed based on its phylogenetic position, genetic divergence and morphological distinctness.

Field diagnosis. Morphology. Raorchestes leucolatus sp. nov. could be morphologically confused with its close relative R. tuberohumerus . However, it can be distinguished from R. tuberohumerus on many aspects of morphology. Raorchestes leucolatus sp. nov. can be distinguished by its smaller size (males) 16.9 mm (16.2–17.1, n=4) (vs. 18.4 mm (17.7–19.0, n=6) in R. tuberohumerus ); head width, HW/SVL=0.38 (0.37–0.39, n= 4) greater than head length, HL/SVL=0.29 (0.28–0.31, n=4) (vs. HW/SVL=0.35 (0.33–0.36, n=6) almost equal to head length (HL/SVL=0.37 (0.36–0.40, n=6) in R. tuberohumerus ); shorter thigh length, TL/SVL=0.45 (0.43–0.46, n=4) (vs. TL/SVL=0.50 (0.46–0.52, n=6) in R. tuberohumerus ); shorter foot length, FOL/SVL=0.36 (0.35–0.36, n=4) (vs. FOL/SVL=0.40 (0.37–0.43) in R. tuberohumerus ); groin region with white blotches (vs. groin region with yellow blotches in R. tuberohumerus ; disc colour orange (vs. disc colour grey to brown in R. tuberohumerus ).

Geography. Found to be restricted to the mid-elevations of Elivalmalai Massif (see natural history and distribution for details).

Ecology. Found to be an understory forest species (n=4) and was observed in short grasses and shrubs along the forest edges.

Description of holotype (all measurements in mm). A small sized bush frog (SVL = 16.9 mm), width of head sub equal to head length (HW = 6.2 mm; HL = 5.2 mm), flat dorsally; snout acutely pointed in total profile, slightly protruding beyond mouth. Snout length is sub equal to diameter of eye (SL = 2.2 mm, EL = 2.3 mm). Canthus rostralis angular, loreal region flat. Interorbital space (IUE = 2.1 mm) flat and sub equal to upper eyelid (UEW = 1.5 mm). Interorbital space between posterior margins of the eyes 1.7 times that of anterior margins (IFE = 3.5, IBE = 5.8 mm). Nostrils oval, nearer to tip of snout. Weak symphysial knob. Eyes small, pupil horizontal. Tympanum indistinct, rounded, barely visible behind the eye. Tongue bifid, granular without papilla. Supratympanic fold from behind eye to shoulder.

Relative length of fingers I<II<IV<III. Finger tips with well developed small disks (fd3 = 0.8 mm; fw3 = 0.5) with distinct circum–marginal grooves, fingers with dermal fringes on both sides. Webbing on palm absent, subarticular tubercles moderate and pre-pollex moderate. Supernumerary tubercles absent.

Hind limb long, heels touch when folded at right angles to the body. Thigh/Femur (TL = 7.8 mm), sub equal to Shank/Tibia (ShL = 7.5 mm); longer than foot (FOL = 6.1 mm) and less than heel to tip of fourth toe (TFOL = 10.2 mm). Relative toe length I<II<III<V<IV, webbing poor; web formula (I 1- 1 II 1- 2 III 1- 2 IV 2- 1 V). Tibiotarsal articulation reaches posterior corner of eye. Outer metatarsal tubercle, supernumerary tubercles and tarsal tubercle absent.

Color in life. Dorsum maroon with a pair of distinct orange patch on the shoulder. An orange coloured horizontal broken band between the upper eyelids. Groin with distinct white blotches, ventrally varying shades of brown with irregular white spots on the belly. Throat darker towards lips, disks on finger and toes distinctly orange. Iris coarsely speckled with varying shades of golden brown, overlaid on an irregular brown markings. Distinct rufous edged speckles around the pupil ( Fig 12 (b)).

Etymology. The species is named after one of its distinct characteristics, the ‘white patch’ on the groin (Greek: leukos = white).

Natural history and distribution. The species was discovered in the mid elevations (894–958 m, n=2) and was observed at forested sites in the Elivalmalai Massif ( Fig 1 & 2 ) situated north of Palghat Gap. Currently there are no reports of any allied species from north of its range. The southern most range of R. tuberohumerus , its geographically closest relative, appears to be Wayanad plateau ( Fig 1 ). Further surveys are needed to verify the occurrence of this species or any close relatives in the lower elevations of Nilgiri Massif.

Figures

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

FIGURE 12. Raorchestes leucolatus sp. nov. (a) profile in life; (b) eye profile in life; (c) dorsal profile of holotype; (d) ventral profile in life; (e & f) dorsal and ventral profile of R. tuberohumerus (note groin and disc coloration).

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.