Contributions to Zoology, 79 (1) – 2010Miguel Vences; Frank Glaw; Jörn Köhler; Katharina C. Wollenberg: Molecular phylogeny, morphology and bioacoustics reveal five additional species of arboreal microhylid frogs of the genus Anodonthyla from Madagascar

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Anodonthyla jeanbai sp. nov. (Fig. 16)


Fig. 16a-f. Specimens of Anodonthyla jeanbai in life, in dorsolateral and ventral views, all from Andohahela National Park. (A) Holotype specimen ZSM 88/2005; (B-F) paratype specimens, all preserved in the UADBA collection.

Holotype. ZSM 88/2005 (field number FGZC 2405), adult male, collected at Andohahela National Park, near our campsite that was located at 24°32.642’S, 46°42.847’E, 1548 m a.s.l., Toliara Province, southeastern Madagascar on 27 January 2005 by P. Bora, F. Glaw and M. Vences.

Paratypes. ZSM 89-96/2005 (field numbers FGZC 2406, 2407, 2409, 2411, 2414, 2416, 2418, 2419) and ZFMK 89187 (=ZSM 97/2005, field number FGZC 2421), six males and three females (see Table 2), all with same data as holotype, and UADBA uncatalogued (FGZC 2408, 2410, 2412, 2413, 2415, 2417, 2420), seven specimens, same data as holotype.

Justification. The phylogenetic tree indicates that A. jeanbai has a very isolated phylogenetic position, without clear relationships to any other Anodonthyla. Its genetic 16S divergence to other species is 9.4-12.1%. Although we have no data on the advertisement call of A. jeanbai, we consider this high genetic divergence in concert with various diagnostic morphological characters as given below to be clearly indicative of its species status.

Diagnosis. A small arboreal frog assigned to Anodonthyla on the basis of the presence of a distinct prepollex in males. Distinguished from all other Anodonthyla by a significant genetic differentiation. A. jeanbai is further distinguished from A. montana, A. emilei, A. vallani, and from the syntopic A. rouxae by smaller size (male SVL 14-20 vs. 23-34 mm), and from A. rouxae by the absence of distinct humeral spines in males (vs. presence). A difference visible in living A. jeanbai and absent from all other Anodonthyla is a short tuberculous fold running from directly behind the eye, slightly bent towards the center of the dorsum, and ending at the level of the forelimb insertion (sometimes continuing along the dorsum; in preserved specimens, this ridge often is only poorly recognizable). Additionally, in A. jeanbai the first finger is extremely reduced and in most specimens is not considerably longer than the prepollex. A. jeanbai is furthermore distinguished from all Anodonthyla, except A. moramora, by the presence of a yellowish pigment on ventral surfaces in life, sometimes completely extending over the venter, or just some yellow pigment on the belly; in A. moramora, the venter often has a greenish shade in life that could be mistaken with the yellow pigment of A. jeanbai whereas other species have greyish, white and black colours on the venter only. A. jeanbai furthermore differs by its very distinct tympanum from various other species where the tympanum is often less clearly visible, and by a comparatively long and narrow head (average ratio HW/HL 0.95, range 0.86-0.98, vs. usually >0.95 and often >1 in all other species). Also distinguished from most specimens of A. nigrigularis, A. theoi and A. vallani by the absence of a blackish vocal sac in males (vs. presence).

Description of holotype. Specimen in good state of preservation (muscle tissue from right thigh removed as tissue sample for molecular analysis). SVL 19.9 mm (for other measurements see Table 2). Body slender; head slightly longer than wide, not wider than body; snout slightly pointed in dorsal view, rounded in lateral views; nostrils directed laterally, slightly protuberant, of same distance to tip of snout and to eye; canthus rostralis indistinct, concave; loreal region straight; tympanum distinct, rounded, its diameter 67% of eye diameter; supratympanic fold clearly recognizable; tongue ovoid, posteriorly broader than anteriorly, free and not notched or forked; small maxillary teeth poorly recognizable; vomerine teeth absent; choanae rounded. Arms moderately thickened; subarticular tubercles well recognizable at the base of fingers; outer metacarpal tubercle distinct; prepollex distinct, extending from the area generally occupied by the inner metacarpal tubercle to the tip of the first finger; tips of first finger and prepollex slightly diverging; fingers without webbing; relative length of fingers 1<2<4<3, inner finger extremely rudimentary with roundish, rudimentary disk, disks of fingers 2-4 distinctly enlarged, of triangular shape; keratinized nuptial pads absent, but a distinctly thickened unpigmented area on inner side of arm. Hindlimbs slender; tibiotarsal articulation reaching tympanum when hindlimb adpressed along body; TL 42% of SVL; lateral metatarsalia strongly connected; metatarsal tubercles poorly recognizable; no webbing between toes; relative length of toes 1<2<5<3<4; third toe distinctly longer than fifth. Skin on dorsum and ventral surface smooth.

Colour. After two years in preservative, dorsum and posterior part of head almost uniformly brown, anterior head slightly lighter brown. A thin (< 0.5 mm) light middorsal line from snout tip to cloaca. Two black spots in the inguinal region. Tympanic region light, bordered by a dark supratympanic fold. Forelimbs without distinct dark crossbands, hindlimbs with distinct dark crossbands. Cloacal region blackish. Throat, chest and ventral parts of limbs dirty yellowish with scattered brown pigment and small whitish dots; belly similarly coloured but more greyish. Thickened ventral sides of arms unpigmented.

In life, dorsum light brown with some very indistinct irregular brown flecking, pale colour covering snout and extending posteriorly to interorbital region, narrow cream vertebral line, extending from cloaca to tip of snout, black oval fleck in groin, smaller irregular black spot lateral in scapular region and on posterior dorsum. Dorsal surfaces of arms and legs light reddish brown with some indistinct irregular darker markings. Ventral colouration in life unknown. Iris bronze with fine black spotting.

Variation. A. jeanbai is a highly polychromatic species. As shown in Fig. 16, the colour pattern might differ considerably, with specimens exhibiting a vertebral stripe and others lacking it. Some specimens have a brown dorsal colouration with dark brown flecks encircled by thin cream lines (Fig. 16e). Many specimens exhibit a more or less regular dark ‘hourglass’ pattern in the scapular region and/or small reddish brown tubercles scattered on dorsum. Larger dark markings might be present on different dorsal body parts. However, all specimens exhibit a yellowish tint on ventral surfaces of limbs and posterior belly, and a tuberculous fold extending from the eye posteriorly to the level of insertion of forearm. Measurements are provided in Table 2.

Etymology. We dedicate this new species to the Malagasy herpetologist Jean Baptiste (Jean-Ba) Ramanamanjato who provided logistic information that proved to be crucial for the success of our expedition to the type locality, at higher elevations in Andohahela National Park.

Natural history. Specimens were found at one single site, a forest with high bamboo density at higher elevations. Specimens were very common and were found at night 1-2 m high on bamboo trunks, but no cophyline calls were heard during the single night of survey at this site. The species occurred in close syntopy with A. rouxae which appeared to be rarer, with only three specimens found at this site.

Distribution. The species is only known from one surveyed site at higher elevation in Andohahela National Park.