Plethodontohyla fonetana, Glaw & Köhler & Bora & Rabibisoa & Ramilijaona & Vences, 2007

Glaw, Frank, Köhler, Jörn, Bora, Parfait, Rabibisoa, Nirhy H. C., Ramilijaona, Olga & Vences, Miguel, 2007, Discovery of the genus Plethodontohyla (Anura: Microhylidae) in dry western Madagascar: description of a new species and biogeographic implications, Zootaxa 1577 (1), pp. 61-68 : 62-64

Plethodontohyla fonetana sp. nov.

( Figs. 1–3 )

Holotype. ZSM 123 /2006 (field number FGZC 917 ), adult female from Bendrao forest (18°47'50'' S, 44°52'53'' E, 420 m above sea level), Tsingy de Bemaraha National Park, Mahajanga Province, western Madagascar; collected on 28 March 2006 by P. Bora, F. Glaw, J. Köhler, and local guides.

Paratype. UADBA 39001 (field number NR 853 ) , adult female from Bendrao forest (18°47'54'' S, 44°52'36''E, 470 m a.s.l.), Tsingy de Bemaraha National Park, Mahajanga Province, western Madagascar; collected on 29 March 1998 by N. H. C. Rabibisoa .

Diagnosis. A rather large cophyline with expanded finger disks that does not closely resemble any other microhylid from Madagascar. Plethodontohyla fonetana differs from almost all other cophylines with expanded terminal finger disks (of the genera Plethodontohyla , Stumpffia , Anodonthyla , Cophyla and Platypelis ) by larger size (54–65 mm versus 14–42 mm SVL). Only two remaining cophyline species with enlarged fingertips are larger: Platypelis grandis (43–105 mm SVL) and Plethodontohyla inguinalis (SVL 55–100 mm). Platypelis grandis differs by much wider finger disks and granular dorsal skin; for a distinction from Plethodontohyla inguinalis , see below. Plethodontohyla fonetana is also immediately recognizable among all other Madagascan microhylids by its characteristic dorsal coloration (ground color light brown with well delimited blackish reticulation). Plethodontohyla fonetana appears to be most closely related to other congeneric species with expanded terminal finger disks ( P. inguinalis , P. mihanika , P. notosticta and P. guentheri ). It differs from these four species by the lack of a distinct dorsolateral border in coloration posterior to the forelimbs, and by two continuous, elevated and sinuous dorsal ridges running from ca. 5 mm behind the eyes to ca. 10 mm in front of the cloaca. Moreover, it differs from P. mihanika , P. notosticta and P. guentheri by much larger size (54–65 mm versus 26–42 mm SVL).

Description of the holotype. Adult female with eggs in the body cavity, in relatively good state of preservation, ventrally opened for inspection of gonads and stomach contents. Body stout; head wider than long, not wider than body; snout rounded in dorsal and lateral views; nostrils directed laterally, slightly protuberant, nearer to tip of snout than to eye; canthus rostralis distinct, sharp; loreal region concave; tympanum very indistinct (poorly reconizable on the right side, not recognizable on the left side), 49% of eye diameter; supratympanic fold conspicuous, long, almost straight; tongue ovoid, posteriorly free; maxillary teeth present; vomerine teeth distinct, forming transversal rows posterior to choanae starting close to maxillae; choanae ovoid. Arms slender; single subarticular tubercles, very distinct at the base of the fingers; distinct paired outer metacarpal tubercles; large inner metacarpal tubercle, forming distinct protuberance; fingers without webbing; relative length of fingers 1<2<4<3, fourth finger clearly longer than second; finger disks distinctly enlarged, triangular. Hindlimbs moderately slender; tibiotarsal articulation reaches beyond insertion of arms when hindlimb adpressed along body; lateral metatarsalia connected; distinct inner and indistinct outer meta- tarsal tubercles present; only traces of webbing between toes; relative length of toes 1<2<5<3<4; third toe distinctly longer than fifth. Skin on dorsal surface smooth with scarce scattered small granules on middorsum, dorsal surface of snout and flanks, with no dorsolateral fold or color border along the flanks. Two slightly sinuous elevated dorsal ridges running from ca. 5 mm behind the eyes to ca. 10 mm in front of the cloaca. Ventral skin relatively smooth.

Measurements: SVL 54.1 mm; head width 23.4 mm; head length 14.9 mm; eye diameter 5.7 mm; tympanum diameter ca. 2.8 mm (poorly recognizable); eye-nostril distance 4.2 mm; nostril-snout tip distance 3.9 mm; nostril-nostril distance 5.0 mm; hand length 17.5 mm; hindlimb length ca. 70.1 mm; foot length including tarsus 32.2 mm; foot length 23.3 mm; tibia length 22.4 mm; length of inner metatarsal tubercle 3.6 mm; width of inner metatarsal tubercle 2.1 mm.

Coloration. In preservative, dorsum brown with a reticulated pattern of distinct black spots of irregular shape and few small white dots. The dark spots are fused to a large, faintly symmetrical, black spot behind the eyes. Towards the flanks the brown ground color changes to light brown, the dark pattern fades to brown, and the whitish dotting becomes more dense. The two dorsal ridges are white and a similar narrow white line is running along the supratympanic fold. Sides of head and tympanic region blackish, sharply bordered by the supratympanic fold. Forelimbs and hindlimbs brown with narrow dark crossbands and white spotting. Highest density of white spots on the posterolateral and anterolateral parts of the shanks. Ventrally, throat dark brown with fine light dots, chest brown with larger white dots and spots, the light color becoming predominant towards the belly. The color in life was similar ( Figs. 1–2 ), perhaps somewhat lighter than in preservative. The iris was greyish with a slightly greenish shade.

Variation. The paratype is generally similar to the holotype in morphology and coloration in preservative, although the dorsal ridges are much less recognizable compared to the holotype and not white. As in the holotype, no distinct dorsolateral color border posterior to the forelimbs. Measurements of the paratype (UADBA 39001) are as follows: SVL 65.0 mm; head width 27.9 mm; eye diameter 6.0 mm; tympanum diameter 3.6 mm; eye-nostril distance 4.6 mm; nostril-snout tip distance 4.0 mm; nostril-nostril distance 5.4 mm; hand length 21.3 mm; hindlimb length ca. 81.9 mm; foot length including tarsus 41.0 mm; foot length 28.6 mm; tibia length 27.5 mm; length of inner metatarsal tubercle 5.2 mm; width of inner metatarsal tubercle 2.5 mm, comparative finger length 1<2<4<3; comparative toe length 1<2<5<3<4.

Natural history, distribution and threat status. Very little information is available. The two type specimens are gravid females. The holotype contained more than 100 (more than 50 on each side) yellowish eggs with a black pole, ca. 2.0– 2.4 mm in diameter, indicating that the specimen was ready for reproduction at the end of the rainy season. The stomach of the holotype contained a large number of medium-sized insect remains (ants, beetles) and pieces of dead leaves from the forest floor. The holotype was found in a night without rainfall on Tsingy rocks within a moderately moist dry forest. In March 2006, our pitfalls at three other sites in the Tsingy de Bemaraha National Park failed to capture any additional Plethodontohyla specimen. The paratype was captured by a pitfall trap next to Tsingy rocks with dead leaves (soil composition: sand and clay complex). Both type specimens were found in the same forest (Bendrao). Accordingly, the known range of the species is extremely small ( Fig. 4 ). Although the actual range is very likely to comprise a larger area, we assume that the new species is endemic to the Tsingy de Bemaraha massif due to the absence of sufficient humidity outside the karstic habitats. Using the same rationale and IUCN criteria as applied during the Global Amphibian Assessment for Madagascan amphibians (see Andreone et al. 2005a) we classify Plethodontohyla fonetana as "Data Deficient".

Etymology. The specific name "fonetana" is the Malagasy word for "stubby" and refers to the general body shape of the new species. It is used as a noun in apposition.

Figures

FIGURE 1. Plethodontohyla fonetana, holotype (ZSM 123/2006) in dorsolateral view, photographed in life.

FIGURE 2. Plethodontohyla fonetana, holotype (ZSM 123/2006) in ventral view, photographed in life.

FIGURE 4. Map of Madagascar showing the known distribution of Plethodontohyla fonetana (black square), P. guentheri (black triangle) and remaining members of the genus Plethodontohyla (gray dots), excluding those species now placed in Rhombophryne. The latter records also exclude P. guentherpetersi, as its generic placement is uncertain.