Saturday, December 11, 2010

The Frogs of the Hyloxalus bocagei Clade (Family Dendrobatidae)

Hyloxalus subpunctatus
Dendrobatid frogs, like other frog clades, have undergone dramatic nomenclatural changes in recent years as the result of molecular studies. One genus, Hyloxalus Jiménez de la Espada, 1870 now contains more than 57 species that over time have been previously placed in genera such as Mannophryne, Colostethus, Cryptophyllobates, and Prostherapis.  Hyloxalus bocagei was first described from Cantón de Quijos, Napo Province, Ecuador.  Spanish zoologist Marco Jiménez de la Espada traveled throughout South America collecting specimens between 1862 and 1865. Three species of the frogs he collected he placed in the genus Hyloxalus – meaning hyla-like. Dunn later moved these frogs to the genus Prostherapis, and Edwards placed them in the genus Colostethus. Today the genus Hyloxalus is known from Panama southward to Peru along the Pacific coast, and on the east side of the Andes from Venezuela, Colombia, Ecuador, Peru eastward into the upper Amazon Basin.

Now Mónica Paez-Vacas and colleagues have examined the H. bocagei clade and report that it contains four previously described species (Hyloxalus bocagei, H. faciopunctulatus, H. maculosus, and H. sauli) as well as two new species (Hyloxalus yasuni and Hyloxalus italoi). The clade is endemic to the eastern Andean slopes and adjacent Amazonian lowlands in southern Colombia, Ecuador and northern Peru. The authors assign the name of Hyloxalus bocagei to the populations surroundings Volcán Reventador (Provincia Napo, Ecuador); describe the tadpoles of Hyloxalus bocagei, H. maculosus, H. italoi, and H. yasuni; and report on the vocalizations of H. bocagei, H. maculosus, H. sauli, H. italoi , and H. yasuni. Adults of italoi and yasuni were indistinguishable using morphological characters, however molecular data, call parameters, and tadpole morphology supported the recognition of these two species as cryptic taxa. Their phylogeny confirms the close relationship of members of the bocagei clade with Andean relatives of Hyloxalus and recurrent dispersal events from the Andes to the Amazon Basin in the late Miocene (less than10 MYA). Their data also support the bocagei clade as the sister to the Andean H. subpunctatus clade.

Members of the bocagei clade are diurnal, stream-side frogs. Males are often found calling on rocks and from crevices, and when disturbed, jump into the water, returning to their calling site several hours later. Males of may also use human modified structures such as plastic drain pipes and concrete walls. The eggs are deposited on the forest floor and guarded by the male, upon hatching he transports them to a stream.

Paez-Vacas, M. I., L. A. Coloma and J. C. Santos. 2010. Systematics of the Hyloxalus bocagei complex (Anura: Dendrobatidae), description of two new cryptic species, and recognition of H. maculosus. Zootaxa 2711: 1–75.

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