Zootaxa 1577: 61–68 (2007) www.mapress.com / zootaxa/
ISSN 1175-5326 (print edition)
Copyright © 2007 · Magnolia Press
ISSN 1175-5334 (online edition)
ZOOTAXA
Discovery of the genus Plethodontohyla (Anura: Microhylidae) in dry western Madagascar: description of a new species and biogeographic implications FRANK GLAW1, 5, JÖRN KÖHLER2, PARFAIT BORA3, NIRHY H. C. RABIBISOA3, OLGA RAMILIJAONA3 & MIGUEL VENCES4 1
Zoologische Staatssammlung, Münchhausenstr. 21, 81247 München, Germany. E-mail:
[email protected] Department of Natural History - Zoology, Hessisches Landesmuseum Darmstadt, Friedensplatz 1, 64283 Darmstadt, Germany. E-mail:
[email protected] 3 Université d’Antananarivo, Département de Biologie Animale, Madagascar. E-mail:
[email protected];
[email protected];
[email protected] 4 Division of Evolutionary Biology, Zoological Institute, Technical University of Braunschweig, Spielmannstr. 8, 38106 Braunschweig, Germany. E-mail:
[email protected] 5 Corresponding author 2
Abstract The cophyline anuran genus Plethodontohyla is considered to be restricted to humid eastern and central Madagascar. Recent surveys of the herpetofauna in the karstic limestone massif "Tsingy de Bemaraha" revealed a distinctive new species which constitutes the first record of this genus in central-western Madagascar. Plethodontohyla fonetana sp. nov. is characterized by large size (snout-vent length up to 65 mm in females), enlarged fingertips, sinuous dorsal folds, and a reticulated dorsal coloration. It is probably closely related to the other Plethodontohyla species with enlarged fingertips. The discovery of the new species suggests the existence of forest corridor between the eastern rainforest stretch and the relatively dry Tsingy de Bemaraha massif during a period of more humid climate. A continuous strip of gallery forest along a river running from the central high plateau to the west might have been sufficient to allow dispersal to the Bemaraha plateau. Key words: Amphibia, Anura, Microhylidae, Plethodontohyla, new species, Madagascar, biogeography
Introduction Cophyline microhylids currently comprise seven genera with 43 described species (Andreone et al. 2005b; Glaw & Vences 2007). Next to the endemic Malagasy-Comoroan family Mantellidae with 12 genera and about 165 species (Glaw & Vences 2006; Glaw et al. 2006) they represent the second largest amphibian radiation in Madagascar. Many new cophyline species have already been discovered, but still await their description. Thus far, cophyline frogs are considered to be largely restricted to rainforest environments or moist highaltitude habitats of the east and the central high plateau, whereas they are unknown from the arid western regions of the island (Blommers-Schlösser & Blanc 1991; Glaw & Vences 1994). The only published record of a cophyline species from a deciduous dry forest refers to a small Stumpffia species in the Ankarafantsika reserve (Blommers-Schlösser & Blanc 1991; Ramanamanjato & Rabibisoa 2002). During recent fieldwork in central western Madagascar, we discovered a distinctive new Plethodontohyla in the Tsingy de Bemaraha National Park. In this paper we describe this new species and discuss the biogeographical implications of its discovery.
Accepted by S. Carranza: 26 Jun. 2007; published: 7 Sept. 2007
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Materials and methods Specimens were collected by opportunistic searching and pitfall trapping, preserved in 70% ethanol and deposited in the collections of the Université d'Antananarivo, Département de Biologie Animale (UADBA) and of the Zoologische Staatssammlung München (ZSM). ZFMK refers to Zoologisches Forschungsmuseum Alexander Koenig, Bonn. Tissue samples for future DNA studies were preserved separately in 99% ethanol. The description of the new species largely follows the format used by Vences et al. (2003) and Glaw & Vences (2007) to allow for a better comparison to other Plethodontohyla species with enlarged fingertips. SVL is used for snout-vent length. Morphological measurements were taken to the nearest 0.1 mm using calipers.
Results 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
