No abstract

Age structure of populations of four species of endemic Malagasy frogs of the genus Mantella (M. aurantiaca, M. baroni, M. bernhardi, M. madagascariensis) was examined by skeletochronology based on 96 specimens from nine different localities.In more than half of these (57%), no lines of arrested growth (LAGs) were found, and the number of LAGs recognized in the remaining specimens was mostly one, and probably two in three specimens. It is generally considered that each LAG corresponds to one year of life; our results therefore confirm that in Mantella populations almost all specimens are in their first or second year of life.

We describe and compare the tadpole morphology of nine species of frogs of the endemic Madagascan genus Mantella based upon specimens identified through DNA barcoding or captive bred. The tadpole morphology of M. crocea/ milotympanum-hybrids, M. madagascariensis, M. pulchra, M. viridis, M. baroni, M. bernhardi and M. betsileo is described for the first time. In general, Mantella have small and generalized tadpoles with a uniform dark colouration. The oral disc is elliptical, emarginated, and positioned anteroventrally. In M. laevigata the oral disc is rounded, not emarginated, and positioned ventrally; eyes are positioned and directed dorsally, while in other species they are directed dorsolaterally. Labial tooth row formulas of Mantella tadpoles differ among some species, and in M. aurantiaca and M. crocea/milotympanum they also show intraspecific variation. Species identification is difficult when considering only morphometric variables. Tadpoles within each species group of the genus do not cluster together (except for some clustering of species belonging to the M. madagascariensis group), confirming that the larval morphology in closely related Mantella species is not suitable for determining phylogenetic relationships. Mantella laevigata, distinguished by tree-hole breeding and parental care, shows the most distinguished larval morphology.

A new species of Anomaloglossus is described from the Venezuelan Guayana; it is the 21 st described species of Anomaloglossus from the Guiana Shield, and the 15 th from Venezuela. This species inhabits rainforest on granitic substrate on the northwestern edge of the Guiana Shield (Estado Amazonas, Venezuela). The new species is distinguished from congeners by sexual dimorphism, its unique male color pattern (including two bright orange parotoid marks and two orange paracloacal spots on dark brown background), call characteristics and other morphological features. Though to the new species is known only from the northwestern edge of the Guiana Shield, its distribution may be more extensive, as there are no significant biogeographic barriers isolating the type locality from the granitic lowlands of Venezuela.

We describe a new species of arboreal frog of the genus Guibemantis, subgenus Guibemantis, from low altitude rainforest in Manombo Special Reserve, south-eastern Madagascar. Previously published phylogenetic analyses of mitochondrial DNA sequences have placed Guibemantis diphonus sp. nov. sister to G. timidus. The new species is distinguished from G. timidus and all other species in the subgenus by a substantial genetic differentiation (≥ 4.4% uncorrected p-distance in the mitochondrial 16S rRNA gene), strongly divergent advertisement call, and some limited morphological differences. It is the smallest known species in the subgenus, with 34-36 mm snout-vent length in adult males. Its advertisement call is unique among other species in the subgenus in being composed of two distinctly different note types (only one note type in the other species).