Wednesday, August 22, 2018

[Herpetology • 2018] Boophis masoalaEye and Webbing Colouration As Predictors of Specific Distinctness: A Genetically Isolated New Treefrog Species of the Boophis albilabris Group from the Masoala Peninsula, northeastern Madagascar

 Boophis masoala
 Glaw, Scherz, Prötzel & Vences, 2018


 We describe a large and distinctive new treefrog species with blue webbing from the west coast of the Masoala peninsula in northeastern Madagascar. Boophis masoala sp. n. is morphologically similar to the other species of the Boophis albilabris group but can be distinguished from them easily by several chromatic characters of the eyes. Despite its similar morphology, it is genetically highly differentiated (10.5–13.3% pairwise p-distance in a segment of the 16S rRNA gene) from all other species in the B. albilabris group including the morphologically most similar Boophis praedictus. Both species share the blue webbing between toes and are distributed on the Masoala peninsula, but so far were not found in close sympatry. Although we recorded the new species only from the unprotected areas near the coast, we are confident that it also occurs within the adjacent Masoala National Park. We discuss the importance of eye colouration as a predictor of specific distinctness in the genus Boophis and that of webbing colouration as taxonomic characters of large treefrogs. Based on a micro-CT scan we provide a comprehensive description of the osteology of the new species, which is the first for any Boophis species, and furthermore describe its distress call which consists of three distinct sections corresponding to (1) the starting phase with closed mouth, (2) the opening of the mouth and (3) the final section with an open mouth. 

Key words: Amphibia, Anura, Mantellidae, Boophis masoala sp. n., biogeography, distress call, osteology

Boophis masoala sp. n. 

Diagnosis: Assigned to the genus Boophis based on the presence of an intercalary element between ultimate and penultimate phalanges of fingers and toes (verified by external and osteological examination), enlarged terminal discs of fingers and toes, lateral metatarsalia separated by webbing, absence of outer metatarsal tubercle, molecular phylogenetic relationships (Fig. 1), and overall similarity to other Boophis species. Assigned to the Boophis albilabris group based on the following combination of characters: large size (snout–vent length of holotype 82.4 mm); well developed webbing between fingers; presence of vomerine teeth; presence of a white line along upper lip; molecular phylogenetic relationships; and overall morphological similarity to B. praedictus and B. albilabris.

Figure 3. Boophis masoala sp. n.:
 (A) Holotype in dorsolateral and (B) ventral view.
Two additional individuals were sampled and sequenced but not collected: (C) ZSM-DNA 00289 and (D) ZSM-DNA 00290, both representing different colour morphs.

Habitat and habits: The holotype was discovered at night perching on branches ca. 3 meters above the ground, in close proximity (ca. 30 m) to the sea shore, but not close to any other water body. Another individual was discovered at night in a tree, ca. 4–5 m above the ground at the edge of the trail that leads from the shore to the EcoLodge, just above a small stream and likewise not more than ca. 50 m distance from the shore. The third individual was found in the same area, but only ca. 2 m above the ground.

Etymology: The specific epithet masoala is used as a noun in apposition and is composed of the Malagasy words ‘maso’ (meaning eye) and ‘ala’ (meaning forest), and is usually translated as ‘eye of the forest’ (e.g. Rübel 2003). In contrast to many other new Boophis species (e.g. B. feonnyala, meaning ‘voice of the forest’) which we noticed first by their distinctive advertisement calls, we discovered B. masoala by its large eyes shining many meters in the torchlight at night, and we did not hear its advertisement calls (in the dry season). In addition, its eye colour turned out to be species-specific, allowing us to distinguish B. masoala from all other species. The specific name furthermore refers to the known distribution of the new species, which might be endemic to the Masoala peninsula. 

Available names: The problems with the identity of the Boophis albilabris holotype were extensively discussed in Glaw et al. (2010) and since then, no new data have become available that would challenge its attribution to the widespread species which occurs mostly at higher elevations of eastern Madagascar. Since the type locality of B. albilabris (‘eastern Imerina’) is in central eastern Madagascar, where B. masoala most likely does not occur, conspecificity of B. masoala and B. albilabris can be excluded with very high probability.


Frank Glaw, Mark D. Scherz, David Prötzel and Miguel Vences. 2018. Eye and Webbing Colouration As Predictors of Specific Distinctness: A Genetically Isolated New Treefrog Species of the Boophis albilabris Group from the Masoala Peninsula, northeastern Madagascar. SALAMANDRA54(3); 163–177. 


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