Raorchestes flaviocularis, 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 : 472-475

6. Raorchestes flaviocularis sp. nov.

( Figures 2 , 3 , 9 & 10 ; Tables 2 & 3)

Holotype: ZSI/ WGRC /V/A/875 ( CESF 1406) (SVL 26.5 mm), collected by S.P. Vijayakumar and Varun R Torsekar in September 2011 from a disturbed forest fragment site (9.6064 N, 77.3033 E) located in a tea garden mosaic, Megamalai Massif ( Fig 1 ), Peninsular India.

Paratype: ZSI/ WGRC /V/A/876 ( CESF 1251) (SVL 23.9), collected by S.P. Vijayakumar, Mrugank V. Prabhu and Mayavan in August 2010 from a disturbed forest fragment site (9.6064 N, 77.3033 E) located in a tea garden mosaic, Megamalai Massif ( Fig 1 ), Peninsular India.

Lineage diagnosis. Raorchestes flaviocularis sp. nov. can be diagnosed phylogenetically as a member of the Ochlandrae clade ( Fig 3 ), showing sister relationship to Raorchestes chalazodes ( Fig 10 a) (see discussion below). Though it exhibits shallow divergence (16S—1.2 %) with its allopatric sister, we diagnose this lineage and consider it for description based on its phylogenetic position ( Ochlandrae clade), distinct morphology (coloration and skin pattern), geographical range and acoustic divergence ( Fig 9 , 10 ).

Field diagnosis. Morphology. Raorchestes flaviocularis sp. nov. shows strong similarity with its sister lineage R. chalazodes in the morphometric variables considered. However, it exhibits very strong divergence in dorsum skin coloration and patterns (see Fig 9 a, 10b). In Raorchestes flaviocularis sp. nov., the green dorsum coloration, with a lichen pattern, do not extend on to the hand and foot (vs. dorsal skin colour uniform green extending on to the hand and foot in R. chalazodes ( Fig 10 a). It exhibits signatures of divergence in the limb length (shorter thigh/femur length (TL/SVL=0.40, 0.40–0.40, n=2) in Raorchestes flaviocularis sp. nov. in comparison to R. chalazodes (TL/SVL=0.43, 0.40–0.45, n=3) and shorter tibia/shank length (ShL/SVL=0.42, 0.42–0.43, n=2) in Raorchestes flaviocularis sp. nov. in comparison to R. chalazodes (ShL/SVL=0.45, 0.44–0.45, n=3). Additionally, the new species can be readily distinguished from all other close relatives by its iris pattern (characterized by very distinct small golden yellow patches on a dark background color) and also the dorsum coloration and skin pattern ( Fig 9 ).

Behaviour. Raorchestes flaviocularis sp. nov. shows divergence from its sister lineage in its shorter call length (0.59±0.07 (N=19) vs. 2.11±0.42 (N=43) in R. chalazodes ), low number of pulses (4.95±0.52 (N=19) vs. 21.08±3.47 (N=24) in R. chalazodes , lower pulse rate (7.36±0.62 (N=19) vs. 9.99±0.96 (N=24) in R. chalazodes and greater dominant frequency (2675.82±74.19 (N=38) vs. 2523.78±62.93 (N=23) in R. chalazodes ) ( Fig 10 ). Considering the short overlap in the range of dominant frequency of the calls of the two lineages, we mainly use strong divergence in the temporal call characteristics as an additional evidence for recognizing and naming this lineage.

Geography. Restricted to the Megamalai Massif (see natural history and distribution for details).

Description of holotype (all measurements in mm). A small sized bush frog (SVL = 26.5 mm), width of head broader than head length (HW = 9.7 mm; HL = 6.7 mm), arched, flat dorsally; snout short and acuminate in total profile, slightly protruding beyond mouth. Snout length is sub equal to diameter of eye (SL = 2.6 mm, EL = 3.2 mm). Canthus rostralis rounded, loreal region slightly concave. Interorbital space (IUE = 2.7 mm) flat, slightly broader than upper eyelid (UEW = 1.7 mm). Interorbital space between posterior margins of the eyes 1.8 times that of anterior margins (IFE = 4.5, IBE = 8.2 mm). Nostrils oval, nearer to tip of snout. Weak symphysial knob. Pupil horizontal. Tympanum rather indistinct, rounded, barely visible behind the eye. Tongue bifid, granular with a distinct retractile papilla. Supratympanic fold from behind eye to shoulder.

Relative length of fingersI<II<IV<III, finger tips with well developed disks (fd3 = 2.0 mm; fw3 = 1.1 mm) with distinct circum-marginal grooves, fingers with dermal fringes on both sides. Webbing on palm absent, subarticular tubercles indistinct and pre-pollex indistinct. Supernumerary tubercles absent.

Hind limb long, heels barely touch when folded at right angles to the body. Thigh/Femur (TL = 10.2 mm), sub equal to Shank/Tibia (ShL = 10.1 mm) and less than heel to tip of fourth toe (TFOL = 15.4 mm). Relative toe length I<II<III<V<IV, webbing moderate web formula (I 1- 1 II 1- 1 III 1- 2 IV 2- 1 V). Tibiotarsal articulation reaches tympanic region. Outer metatarsal tubercle, supernumerary tubercles and tarsal tubercle absent.

Color in life. Dorsum with a distinct lichen pattern with uniform green colouration ( Fig 9 (a)), the pattern broken irregularly exposing the brown fleshy skin colouration; dorsal pattern extends to mid belly laterally and to dorsal surface of femur, tibia and lower tarsus. Canthus region fleshy brown with occasional green patches in few individuals. Dorsal parts of arms, fingers and disc colour similar to canthus region. Groin, anterior and posterior femur, tibia and tarsus flesh coloured. Iris dark brown with distinct irregular golden yellow patches.

Etymology. The species is named after the ‘metallic yellow’ colour of the iris (Latin: flavin = yellow; oculus = eye).

Natural history and distribution. A sub-canopy lineage (325 cm, n=2), it is difficult to locate due to its ventriloquistic call and occurrence in the sub-canopy. Like other members of the Ochlandrae clade, it was also heard calling from Ochlandra grass patches. However, the two individuals whose descriptions are given were obtained from a highly disturbed forest fragment, on leaves of short trees (<5 m). Calls were also recorded from high in the canopy. Considering the strong association of Ochlandrae clade lineages with Ochlandra reeds, further observations are needed to verify the habitat association of this new lineage. It is a species of high elevations (1459–1569 m, n =10), and restricted in distribution to the Upper Manalar Plateau, Megamalai Massif ( Fig 1 & 2 ) in the southern Western Ghats. Based on our call recordings in the adjoining Anaimalai Massif ( Fig 1 ), we anticipate a related lineage or an isolated population.

Figures

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

FIGURE 9. Raorchestes flaviocularis sp. nov. (a) profile in life; (b) eye profile in life; (c) dorsal profile of holotype; (d) ventral profile of holotype.

FIGURE 10. Waveform and spectrogram of (a. Rarchestes chalazodes, top: waveform, bottom: spectrogram) and its sister lineage (b. Raorchestes flaviocularis sp. nov., top: waveform, bottom: spectrogram). The two lineages show strong divergence in the temporal structure of the call (see text).

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.