In this study, we used analyses of stable isotopes of nitrogen (delta(15)N) and carbon (delta(13)C) to determine the trophic ecology of the monitor lizard Varanus mabitang. Stable isotopes from claws, gut contents, and soft tissues were measured from the type specimen. Samples from Varanus olivaceus, Varanus prasinus, Varanus salvator, the herbivorous agamid lizard Hydrosaurus pustulatus, and some plant matter were included for comparison. Our data show a rapid decrease in delta(13)C (about 10 per thousand) from food plants towards gut contents and soft tissues of herbivorous species. For the varanids, we found a significant linear correlation of decreasing delta(13)C and increasing delta(15)N from herbivorous towards carnivorous species. In terms of trophic isotope ecology, the type specimen of V. mabitang is a strict herbivore. Thus it differs significantly in its isotopic composition from the morphologically next closest related species V. olivaceus. The most highly carnivorous species is V. salvator, while delta(15)N values for V. prasinus and V. olivaceus are intermediate. Claws provide very valuable samples for such measurements, because they can be sampled from living animals without harm. Additionally, their range of variability is relatively small in comparison with measurements from soft tissues.
The subgenus Brygoomantis in the Madagascar-endemic genus Mantidactylus contains 12 nominal species but is in urgent need of taxonomic revision as many additional, genetically divergent but undescribed candidate species have been identified. We here take a first step towards a better resolution of this group by describing a new species, Mantidactylus schulzi sp. nov., occurring at the Tsaratanana and Manongarivo Massifs, differentiated in genetic, bioacoustic and sometimes morphological characters from its closest relatives. We show that upon detailed study, most species in Brygoomantis can be delimited by concordant differentiation of mitochondrial and nuclear DNA, and by bioacoustic and morphological differences. We flag this group of morphologically similar frogs as a test case where molecular data on historical type specimens by ancient DNA methods might be needed to reach a satisfying clarification of taxonomy and nomenclature. However, the status of the new species M. schulzi is not in doubt as it is morphologically distinct from most historical type specimens, and microendemic to a region in northern Madagascar from where no earlier names exist.
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.
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