Wednesday, March 20, 2013

Rediscovery of the Martinique dendrobatid frog Allobates chalcophis

Allobates chalcopis Photo credit: Fey Magazine

The native herpetofauna of the Lesser Antilles is made up of a relatively few families. Most of the Lesser Antilles native amphibians belong to the genus Eleutherodactylus that have direct development. Eleutherodactylus frogs radiated early in the Greater Antilles  and subsequently dispersed towards the Lesser Antilles. A few amphibians dispersed over water from South America into the Lesser Antilles, an idea supported by molecular data. These include: Leptodactylus fallax, Pristimantis euphronides and P. shrevei. Other clades of small terrestrial vertebrates from mainland South America are also represented in the island chain, particularly snakes, anoles and skinks.

One species of dendrobatidae frog was discovered in 1984 on Martinique, it was described in 1994, but despite field work to locate the species cause it was not found again. The original description suggested that Allobates chalcopis may be the sister taxon to Mannophryne on because they shared a dark throat collar and occurrence of Mannophryne in northern Venezuela and Trinidad and Tobago. However, using morphology and karyotype the species was allocated to the dendrobatid genus Allobates.

Now, 20 years after the last observation of the species, Fouquet and colleagues (2013) located an isolated population of Allobates chalcopis in Martinique. The rediscovery allowed the species’ phylogenetic position to be confirmed. It is nested within a clade of lowland Amazonian Allobates but nonetheless distantly related to any known species of the group. The arrival of the species in Martinique likely corresponds to an overseas dispersal from South America during the late Miocene. A point in time previously hypothesized for the arrival of Bothrops lanceolatus and Leptodactylus fallax; two other species endemic to Martinique and surrounding islands. Of interest  the species was not found at its type locality (500 m ASL) but 300 m higher in altitude The frogs habitat had shifted upward, and the frog was found in herbaceous areas near the summit of Mt. Pelee. The authors suggest the need for a reassignment of the current Red List status.

Antoine Fouquet , Kévin Pineau , Miguel Trefaut Rodrigues , Julien Mailles , Jean-Baptiste Schneider, Raffael Ernst & Maël Dewynter (2013) Endemic or exotic: the phylogenetic position of the Martinique Volcano Frog Allobates chalcopis (Anura: Dendrobatidae) sheds light on its origin and challenges current conservation strategies, Systematics and Biodiversity, DOI:10.1080/14772000.2013.764944

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