Raorchestes indigo, 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 : 475-477

7. Raorchestes indigo sp. nov.

( Figures 2 , 3 & 11 ; Tables 2 & 3)

Holotype: ZSI/ WGRC /V/A/877 ( CESF 1437), a female (SVL 25.7 mm), collected by S.P. Vijayakumar and K.P. Dinesh in September 2011 from a stunted forest site (13.1333 N, 75.2704 E), Kudremukh Massif ( Fig 1 ), Western Ghats, Peninsular India.

Paratype: ZSI/ WGRC /V/A/878 ( CESF 123), a female (SVL 24.4 mm), collected by S.P. Vijayakumar and M.S. Chaitra in October 2008 from a stunted forest site (13.1347 N, 75.2705 E) Kudremukh Massif ( Fig 1 ), Western Ghats, Peninsular India.

Lineage diagnosis. Raorchestes indigo sp. nov. could be readily diagnosed by its deep divergence (16S—6.4%) on the phylogenetic tree ( Fig 3 ), with an unresolved relationship status within clade N. It is morphologically distinct ( Fig 11 ) from all other members of the subclade N. It is geographically restricted to the high elevations of the Kudremukh Massif. The lineage is diagnosed based on four axes: phylogenetic position, genetic divergence, morphological distinctness and geographical distribution.

Field diagnosis. Morphology. There are no close relatives (within the clade N) that could be confused with this lineage. All can be readily distinguished by a combination of the following characteristics. (1) Size (SVL 24.3–25.7 mm, n=5); (2) Dorsum greenish with irregular black and yellow spots/blotches; (3) ventrally uniform bluish white ( Fig 11 (d)) (4) indigo coloration of the groin, posterior arm pits, anterior and posterior femur, tibia and tarsus (unique among the species of Raorchestes , Fig 11 (d)); (5) iris silvery brown ( Fig 11 (b)).

Geography. Restricted in distribution to the high elevations of the Kudremukh Massif (see natural history and distribution for details).

Description of holotype (all measurements in mm). A small sized bush frog (SVL = 25.7 mm), width of head broader than head length (HW = 10.1 mm; HL = 7.0 mm), flat dorsally; snout acutely pointed, slightly protruding beyond mouth. Snout length is sub equal to diameter of eye (SL = 3.2 mm, EL = 2.8 mm). Canthus rostralis angular, loreal region flat. Interorbital space (IUE = 3.2 mm) flat and broader than upper eyelid (UEW = 2.3 mm). Interorbital space between posterior margins of the eyes 1.7 times that of anterior margins (IFE = 5.2, IBE = 8.9 mm). Nostrils oval, nearer to tip of snout. Weak symphysial knob. Pupil horizontal. Tympanum indistinct, barely visible behind the eye. Tongue bifid, granular with a retractile papilla. Supratympanic fold from behind eye to shoulder.

Relative length of fingers I<II<IV<III, finger tips with well developed disks (fd3 = 1.1 mm; fw3 = 0.9 mm) with distinct circum–marginal grooves, fingers with dermal fringes on both sides. Webbing on palm absent, subarticular tubercles moderate and pre-pollex tubercle moderate. Supernumerary tubercles absent.

Hind limb long, heels barely touch when folded at right angles to the body. Thigh/Femur (TL = 10.7 mm) sub equal to Shank/Tibia (ShL = 11.1 mm); sub equal to foot (FOL = 9.7 mm) and less than heel to tip of fourth toe (TFOL = 15.1 mm). Relative toe length I<II<III<V<IV, webbing moderate, 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, canthal region, lateral parts distinctly green with bluish tinge; posterior arm pits, groin, anterior and posterior femur, tibia and tarsus distinctly indigo varying in lighter to darker (at groin) shades. Dorsum with irregular fine black blotches, denser towards head region. Ventrally uniform bluish white ( Fig 11 d), throat white with yellow at the lip margins. Iris with a distinct silvery background, coarsely speckled with shades of brown.

Etymology. The species is named after the unique ‘indigo’ colour of the groin and other under parts of the body. The specific epithet “ indigo ” is used as a noun in apposition to generic name.

Natural history and distribution. A range restricted species, observed in the high elevation (> 1700 m) stunted forests around the highest peak in the Kudremukh Massif ( Fig 1 & 2 ). All the individuals were observed on the forest floor on leaves (avg. 116 cm above ground level, n=6). Further surveys are needed to locate populations in other high elevations zones within Kudremukh Massif and also to explore the presence of any allied lineages in the adjacent Pushpagiri Massif.

Figures

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

FIGURE 11. Raorchestes indigo 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.