Platypelis olgae, Rakotoarison, Andolalao, Glaw, Frank, Vieites, David R., Raminosoa, Noromalala R. & Vences, Miguel, 2012

Rakotoarison, Andolalao, Glaw, Frank, Vieites, David R., Raminosoa, Noromalala R. & Vences, Miguel, 2012, Taxonomy and natural history of arboreal microhylid frogs (Platypelis) from the Tsaratanana Massif in northern Madagascar, with description of a new species, Zootaxa 3563, pp. 1-25 : 17-20

Platypelis olgae sp. nov.

Holotype. ZSM 1666/2010 ( ZCMV 12402), adult male, collected at the Tsaratanana Massif, between Camps 3 (Bepia) and 4 (Andranomadio), without precise geographical coordinates or altitude data, but located in between these two campsites (coordinates given in Materials and Methods) with altitudes of 2294 and 2503 m a.s.l., on 16 June 2010, by M. Vences, D. R. Vieites, R.-D. Randrianiaina, S. Rasamison, and E. Rajeriarison.

Paratypes. ZSM 1667/2010 ( ZCMV 12428, female) and ZSM 1668/2010 (DRV 6225, male), both collected at Tsaratanana Camp 5 (Amboditsaratanana), 14.08019°S, 48.98536°E, 2457 m, on 18 June 2010, by the same collectors as holotype.

Diagnosis and comparisons. Assigned to the genus Platypelis in the Cophylinae based on enlarged terminal discs on fingers and toes, absence of finger-like prepollex, absence of nuptial pads, occurrence in Madagascar, and molecular phylogenetic relationships. Distinguished from all other cophyline species with enlarged discs on fingers and toes by combination of the following character states: small body size (adult SVL 20–22 mm), ventral side of body and limbs with greenish or yellowish color especially on throat, dorsally without a conspicuous pattern of three symmetrical dark patches, no sharp border between dorsal and lateral color, toe 3 as long or slightly longer than toe 5, hindlimb reaching between forelimb and tympanum when adpressed along body, vomerine teeth absent, males with prepollical tubercle but lacking a finger-like prepollex as typical for Anodonthyla .

Distinguished from other species of Platypelis and Cophyla as follows: from C. phyllodactyla , C. berara , P. alticola , P. cowanii , P. grandis , P. mavomavo , P. milloti , P. pollicaris , and P. tuberifera by smaller body size (adult SVL 20–22 mm vs. 23–105 mm); and from all these species plus P. tsaratananaensis and P. t e t r a, by the absence or rudimentary state of vomerine teeth (vs. presence). Furthermore distinguished from all these species except P. mavomavo and juvenile P. grandis by the presence of green-yellow color on the ventral side (vs. absence).

Three other species are small-sized and lack vomerine teeth as P. olgae , i.e., P. barbouri , P. r a v u s, and probably C. occultans (state of vomerine teeth requires confirmation). The new species differs from P. barbouri by greenyellow color on the ventral side (vs. reddish), from P. r a v u s by absence of a dorsal pattern consisting of three dark symmetrical patches (vs. presence), and from P. occultans by a green-yellow venter (vs. uniform grey). Further distinguished from these three species as well as all other microhylids by molecular relationships and genetic divergence: the morphologically similar small-sized species P. barbouri and P. r av u s are placed with high support into different clades, not closely related to P. olgae ( Fig. 7 ), and the uncorrected pairwise divergence in the 16S fragment studied herein is>10% to all other cophylines included in the analysis.

Available earlier names. Few junior synonyms of nominal species of Platypelis or Cophyla exist that need to be considered as possible earlier names for P. olgae ( Blommers-Schlösser & Blanc 1991) . Paracophyla tuberculata Millot & Guibé is morphologically similar according to the original description (small size, absence of vomerine teeth) but has a longer hindlimb (tibiotarsal articulation reaching the eye), and due to its type locality (Andasibe, at mid-altitude in the northern central east of Madagascar) its established synonymy with Platypelis barbouri which is common at this site is very plausible. Other available names are Platyhyla verrucosa Mocquard , Platyhyla voeltzkowi Boettger , and Cophyla tuberculata Ahl , all junior synonyms of Platypelis grandis ; the name-bearing types of these nomina are large-sized and have strongly tuberculated dorsal skin (even the probably juvenile types of C. tuberculata measures 26 mm SVL; Blommers-Schlösser & Blanc 1991), excluding their possible conspecificity with P. olgae .

Description of the holotype. Adult male in good state of preservation, some muscle tissue removed from right thigh. Snout-vent length 20.3 mm. Body slender; head slightly longer than wide, not wider than body; snout bluntly rounded in dorsal and lateral views; nostrils directed almost laterally, not protuberant, nearer to tip of snout than to eye; canthus rostralis indistinct, very slightly concave; loreal region plain; tympanum moderately distinct, 69% of eye diameter; supratympanic fold moderately distinct, almost straight; tongue ovoid, not bifid or notched; weakly expressed maxillary teeth present; vomerine teeth not visible; choanae rounded. Forelimbs slender; subarticular tubercles on all fingers single, flat, but relatively poorly recognizable; outer metacarpal tubercle relatively large and flat, but poorly distinct; inner metacarpal tubercle large, forming distinct protuberance at base of first finger; hand with traces of webbing only recognizable between fingers 3 and 4; fingers distinctly flattened and broad along entire length; relative length of fingers 1<2<4<3, fourth finger slightly longer than second; finger discs distinctly enlarged, slightly triangular; nuptial pads absent. Hindlimbs slender; tibiotarsal articulation reaching between forelimb and tympanum when hindlimb adpressed along body; tibia length, 41% of SVL; lateral metatarsalia strongly connected; inner metatarsal tubercle small and flat, difficult to recognize; outer metatarsal tubercle absent; webbing between toes very weakly developed, with traces of webbing between third and fourth toe; subarticular tubercles on toes hardly recognizable; toes flattened and relatively broad along their entire length; relative length of toes 1<2<5<3<4; third toe very slightly (left) to distinctly (right) longer than fifth.

Dorsal skin smooth, without dorsolateral folds. Ventral skin smooth on throat and chest and moderately granular on belly.

After two years in 70% ethanol, dorsum almost uniformly brown with distinctly lighter brown on anterior head (anterior to eyes). Forelimbs and hindlimbs dorsally brown with moderately distinct white dots, becoming more evident on hands and feet. No recognizable dark crossbands on arms and limbs. Ventrally, marbled brown and white on throat, brown and yellowish on chest, dark brown and whitish on belly, and brown and yellowish on limbs.

Variation. The two known males (holotype and paratype) have small tubercles scattered over the dorsal surface, while the female was more smooth. Both paratypes had a yellow ventral ground color and less amount of dark pattern as compared to the holotype. The female paratype (ZSM 1667/2010) showed no differentiation from the holotype in the mitochondrial DNA fragment studied ( Fig. 7 ; male paratype not sequenced). In all specimens, the third toe is as long as or slightly longer than toe five. Finger three is as long as finger four in all three specimens. In none of the specimens are vomerine teeth visible, but under the oral mucosa posteromedial bony ridges can be noticed when carefully probing with a needle, bearing denticulations that possibly could represent rudimentary vomerine teeth.

Etymology. This species is dedicated to the late Prof. Olga Ramilijaona, former head of the zoology department at UADBA, aunt and mentor of the first author (AR), and friend and collaborator of MV, FG, NR, and DRV. The name is a patronym in recognition of Olga's tireless and successful efforts to develop zoological science in Madagascar.

Natural history. The holotype was found at daytime on a small log that had been felled and where it might have emerged from a tiny water filled tree hole. The two paratypes were found hidden among dense layers of moss and leaf litter on the ground. No further information is available on the natural history, reproduction, or calls of this species.

Figures

FIGURE 7. 50 % majority-rule consensus tree from a Bayesian analysis of partial DNA sequences of the 16 S rRNA gene of Platypelis. Values on nodes are posterior probabilities (not shown if <0.95). Cophyla berara was used as the outgroup (not shown).