Raorchestes echinatus, 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 : 468-470

4. Raorchestes echinatus sp. nov.

( Figures 2 , 3 & 7 ; Tables 2 & 3)

Holotype: ZSI/ WGRC /V/A/871 ( CESF 1412), an adult male (SVL 18.0 mm), collected by S.P. Vijayakumar and K.P. Dinesh in September 2011 from a grassland site (13.4228 N, 75.7695 E), Baba Budan Massif ( Fig 1 ), Western Ghats, Peninsular India.

Paratype: ZSI/ WGRC /V/A/872 ( CESF 1414), an adult male (SVL 19.0), collected by collected by S.P. Vijayakumar and K.P. Dinesh in September 2011 from a grassland site (13.4228 N, 75.7695 E), Baba Budan Massif ( Fig 1 ), Western Ghats, Peninsular India.

Lineage diagnosis. This lineage belongs to the larger clade N ( Fig 3 ), with an unresolved relationship status within this clade, but with very high levels (16S—7.3%) of divergence from all other lineages. It exhibits a number of unique morphological characteristics ( Fig 7 ) (see field diagnosis) and shows strong affinity towards grasslands and is restricted geographically to the high elevations of Baba Budan Massif in the Western Ghats. We diagnose this lineage based on the deep genetic divergence, morphology, ecology and geography.

Field diagnosis. Morphology. Raorchestes echinatus sp. nov. superficially resembles R. tuberohumerus in adult male size SVL 18.4 (18.0–19.0, n=3) (vs. adult male size SVL 18.3 (17.7–19.0, n=6) in R. tuberohumerus ), however a number of divergent characters could be discerned; larger head width, HW/SVL=0.40 (0.38–0.41, n=3) (vs. HW/SVL=0.35 (0.33–0.36, n=6) in R. tuberohumerus ); shorter head length, HL/SVL=0.27 (0.24–0.29, n=3) (vs. HL/SVL=0.37 (0.36–0.40, n=6) in R. tuberohumerus ); shorter eye length, EL/SVL=0.104 (0.099–0.108, n=3) (vs. EL/SVL=0.127 (0.111–0.137, n=6) in R. tuberohumerus ); shorter tibia, ShL/SVL=0.36 (0.34–0.38, n=3) (vs. ShL/SVL=0.46 (0.41–0.49, n=6) in R. tuberohumerus ); shorter femur length, TL/SVL=0.409 (0.39–0.43, n=3) (vs. TL/SVL=0.50 (0.46–0.52, n=6) in R. tuberohumerus ); skin, on the dorsum rough with minute horny ridges, more spinular and on the dorsal surface of limbs smooth; lateral and ventral sides granular (vs. sparsely granular dorsum in R. tuberohumerus ); yellowish throat finely speckled in brown (vs. flesh coloured, speckled in black in R. tuberohumerus ); ventral coloration, white mottlings on a dark background, the pattern extending into femur, tibia, tarsus (vs. anterior thigh region characterized by dark colouration with distinct yellow blotches in R. tuberohumerus ).

Additionally the new species, Raorchestes echinatus sp. nov., can be easily distinguished morphologically from known congeners in clade N, that potentially overlap with its geographical range, by its size, horny ridges on the dorsum, ventral and throat coloration.

Ecology. A species of the open habitat and all individuals were observed in the grasslands.

Geography. Distribution data suggests that it is restricted to the Baba Budan Massif (see natural history and distribution for details).

Description of holotype (all measurements in mm). A small sized bush frog (SVL = 18.0 mm), width of head broader than head length (HW = 6.9 mm; HL = 4.8 mm), flat dorsally; snout short and pointed, slightly protruding beyond mouth. Snout length is sub equal to diameter of eye (SL = 2.2 mm, EL = 1.9 mm). Canthus rostralis angular, loreal region flat. Interorbital space (IUE = 2.2 mm) flat and sub equal to upper eyelid (UEW = 1.5 mm). Interorbital space between posterior margins of the eyes 1.6 times that of anterior margins (IFE = 3.7, IBE = 5.9 mm). Nostrils oval, nearer to tip of snout. Weak symphysial knob. Pupil horizontal. Tympanum indistinct, rounded, barely visible behind the eye. Tongue bifid, granular without a papilla. Supratympanic fold from behind eye to shoulder.

Relative length of fingers I<II<IV<III, finger tips with moderate disks (fd3 = 0.9 mm; fw3 = 0.7 mm) with distinct circum–marginal grooves, fingers with dermal fringes on both sides. Webbing on palm absent, subarticular tubercles moderate, rounded and pre-pollex tubercle indistinct. Supernumerary tubercles absent.

Hind limb long, heels do not touch when folded at right angles to the body. Thigh/Femur (TL = 7.4 mm) sub equal to Shank/Tibia (FL = 6.6 mm) and foot (FOL = 7.3 mm) and less than heel to tip of fourth toe (TFOL = 11.4 mm). Relative toe length I<II<III<V<IV, webbing absent. Tibiotarsal articulation reaches posterior corner of eye. Outer metatarsal tubercle, supernumerary tubercles and tarsal tubercle absent.

Color in life. Dorsum with olive patches on a brown background with rufous tinge, distinct spinular tubercles behind the head; a mid dorsal ridge coloured off-white from the snout tip to vent ( Fig 7 a); ventrally a distinct mid ventral white line ( Fig 7 d), belly predominantly white with black irregular interconnected patches. Ventral pattern extends to femur tibia and tarsus, throat yellow finely speckled with brown. Iris with irregular golden speckles with maroon edges and a distinct brown band on the lower half and brown towards anterior and posterior edges.

Etymology. The species is named after the spinular projections on the dorsum (Latin: echino = spiny).

Natural history and distribution. All individuals were observed in grasslands on grass blades (30.8 cm, n=5). The species was observed only in the higher elevations (1464−1864 m, n=6) of Baba Budan Massif ( Fig 1 & 2 ). Further surveys are needed to verify the presence of either conspecifics or close relatives of this lineage in the adjoining Massifs of Kudremukh and Pushpagiri.

Figures

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

FIGURE 7. Raorchestes echinatus sp. nov. (a) profile in life; (b) eye profile in life; (c) dorsal profile of holotype; (d) ventral profile in life.

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.