Philautus singu, Meegaskumbura, Madhava, Manamendra-Arachchi, Kelum & Pethiyagoda, Rohan, 2009

Meegaskumbura, Madhava, Manamendra-Arachchi, Kelum & Pethiyagoda, Rohan, 2009, Two new species of shrub frogs (Rhacophoridae: Philautus) from the lowlands of Sri Lanka, Zootaxa 2122, pp. 51-68 : 59-62

Philautus singu , new species

( Figs. 4–7 )

Material examined. Holotype: mature male, 16.2 mm SVL, WHT6034, Kitulgala, alt. 101 m (6°59'N, 80°20'E), coll. 22 February 1999.

Paratypes: mature males, 16.6 mm SVL, WHT6340, Kottawa Forest Reserve (Galle), alt. 60 m (06°06’N, 80°20’E), coll. 3 June 1999; 16.1 mm SVL, WHT5977, Sinharaja World Heritage Site (near Kudawa), alt. 513 m (06°25’N, 80°25E), coll. 25 January 1999; 16.1 mm SVL, WHT6341, Kottawa Forest reserve (Galle), alt. 60 m (6° 5'N, 80°18’E), coll. 3 June 1999.

Diagnosis. Philautus singu is distinguished from all its Sri Lankan congeners by the following combination of characters: size small, mature males 16.1-16.6 mm SVL; a prominent tubercle present on upper eyelid; tympanum distinct; supratympanic fold distinct; canthal edges rounded; vomerine ridge absent; throat, chest and belly granular.

Description. Body slender. Head laterally convex above. Snout obtusely pointed in dorsal view, rounded in lateral view. Canthal edges rounded. Loreal region concave. Interorbital space convex. Internasal space concave. Nostrils oval. Pupil oval, horizontal. Tympanum distinct, oval, oblique, its outer rim distinct. Pineal ocellus absent. Vomerine ridge absent. Tongue moderate, emarginate, sometimes (n = 1) bearing a rounded lingual papilla. Supratympanic fold distinct. Cephalic ridges absent. Co-ossified skin on head absent. Upper and lower arms short, thin. Fingers slender. Relative length of fingers, 1 <2 <4 <3. Tips of fingers with discs bearing circum-marginal grooves. Webbing and lateral dermal fringe absent on fingers. Subarticular tubercles on fingers prominent, oval, single, sometimes absent on fingers III (n = 2) and IV (n = 2). Prepollex oval, distinct. Two palmar tubercles, oval, distinct; outer tubercle bifid. Supernumerary tubercles present. Thigh, shank slender. Toes thin, relative length 1 <2 <3 = 5 <4 (holotype), (1 <2 <5 <3 <4, WHT6340), (1 <2 <3 <5 <4, WHT5977, WHT6341). Tips of toes with discs, with circum-marginal groves. Webbing present on toes. Subarticular tubercles on toes prominent, oval, single, sometimes absent on toe V (n = 2). Inner metatarsal tubercle distinct, oval. Outer metatarsal tubercle absent. Tarsal fold absent; some dermal tubercles on outer edge of foot. Supernumerary tubercles on toes absent. Tarsal tubercle absent. Dorsal and lateral parts of snout, between eyes, side of head, anterior part of back, posterior part of back, both upper and lower flanks with scattered, glandular tubercles. Dorsolateral fold absent. Dorsal and lateral parts of upper arm, lower arm, thigh, shank and foot with scattered glandular tubercles. Throat, chest, belly and ventral side of thigh granular; underside of thigh smooth. Nuptial pad absent. Internal vocal slits present.

Coloration in life. Dorsal and lateral parts of head and body brown ( Fig. 4 ). Interorbital area dark brown. A dark-brown “W”-shaped marking on mid-back. Upper flank brown, lower flank yellow with brown pigments. Inguinal zone pale yellowish brown. Loreal region dark brown. Tympanic region blackish brown. Upper half of tympanum dark brown, lower half pale yellowish light brown. Upper lip brown with paleyellow patches. Dorsal and lateral parts of forelimb pale yellow with brown pigments, lacking distinct crossbars. Thigh and shank pale brown with three dark-brown crossbars. Dorsal side of foot pale brown with darker patches. Posterior thigh pale brown. Throat and margin of throat with dark-brown pigments on a paleyellow background. Chest, belly, thigh and webbing on toes with dark-brown pigments and pale-yellow patches.

Coloration in alcohol (based on holotype, WHT6034). Dorsal and lateral parts of head and body brown. Interorbital area dark brown. A dark-brown “W”-shaped marking on mid-back. Upper flank brown, lower flank yellow with brown pigments. Inguinal zone pale yellowish brown. Loreal region brown. Tympanic region dark brown. Upper half of tympanum dark brown, lower half pale yellowish light brown. Upper lip brown with pale-yellow patches. Dorsal and lateral parts of forelimb pale yellow with brown pigments; no distinct crossbars. Thigh and shank pale brown with three dark-brown crossbars. Dorsal side of foot pale brown with dark-brown patches. Posterior side of thigh pale brown. Throat and margin of throat with darkbrown pigments on a pale-yellow background. Chest, belly, thigh and webbing on toes with dark-brown pigments and pale-yellow patches.

Measurements of holotype (WHT6034, in mm): DBE, 6.3; DFE, 3.6; DL, 0.7; DW, 1.0; ED, 2.5; EN, 2.0; ES, 2.3; FEL, 7.7; FL I, 1.2; FL II, 1.7; FL III, 3.0; FL IV, 2.2; FOL, 11.1; HL, 6.4; HW, 6.2; IML, 0.9; IN, 1.8; IO, 1.6; LAL, 3.2; MBE, 2.2; MFE, 4.0; MN, 5.7; NS, 1.2; PAL, 5.1; SVL, 16.2; TBL, 8.2; TL I, 1.3; TL II, 1.7; TL III, 2.8; TL IV, 3.9; TL V, 2.8; TYD, 0.7; TYE, 0.7; UAW, 3.6; UEW, 2.2.

Etymology. The species name is Sinhala for horn, an allusion to the horn-like tubercles on the upper eyelids of this frog; applied as a noun in apposition.

Remarks. Morphologically, Philautus singu is reminiscent of P. d e c o r i s, P. m i t t e r m e i e r i and P. t a n u, new species. It is distinguished from P. decoris and P. mittermeieri , however, by the presence of a prominent tubercle on the upper eyelid (absent in P. mittermeieri , P. decoris and P. t a n u); by having the snout rounded in lateral aspect (pointed in P. mittermeieri , and obtusely pointed in both P. decoris and P. tanu ); by the absence of a tarsal tubercle (present in P. mittermeieri and P. d e c o r i s); absence of a lateral dermal fringe and webbing on fingers (present in P. m i t t e r m e i e r i and P. decoris ); and by the absence of a tarsal fold (presenct in both P. mittermeieri and P. d e c o r i s).

Distribution. We observed males of P. singu perched on leaves of shrubs, 0.5-1.5 m above ground level, in the rainforest understory. Although we recorded the species only from the Kottawa and Kitulgala Forest Reserves, it probably occurs also in other rainforest patches in the wet-zone lowlands of Sri Lanka.

Figures

FIGURE 4. Philautus singu (WHT 6340), in life, Kottawa Forest Reserve, Galle.

FIGURE 5. Philautus singu: a, lateral; b, dorsal; and c, ventral aspects, respectively, of head of holotype, male, WHT 6034, 16.2 mm SVL. Scale bar: 1 mm.

FIGURE 6. Philautus singu: a, ventral aspect of left manus; b, ventral aspect of left pes; and c, semi-diagrammatic representation of left-pes webbing pattern of the holotype, male, WHT 6034, 16.2 mm SVL. Scale bar: 1 mm.

FIGURE 7. South-western Sri Lanka, showing the distribution of Philautus singu (squares) and P. t a n u (circles), and place-names cited in the text.