Bona, P. and Alcalde, L. 2009. Chondrocranium and skeletal development of Phrynops hilarii (Pleurodira: Chelidae). -Acta Zoologica (Stockholm) 90: 301-325The present study represents the first comprehensive contribution to the knowledge of the skeletal development of a pleurodiran turtle, Phrynops hilarii (Pleurodira, Chelidae). The most remarkable features found are: (1) absence of ascending process on pterygoquadrate cartilage; (2) presence of ossification centres for the epiotics; (3) as in other pleurodirans, dorsal ribs IX and X are 'sacralized'; (4) contact between ilium and carapace occurs later in ontogenetic development; (5) suture between ischia, pubes and plastron occurs in posthatching specimens; (6) contrary to previous interpretations, the phalangeal formula of the pes of P. hilarii is 2 : 3 : 3 : 3 : 5; (7) the hooked bone represents the fifth metatarsal.

We studied the external and oral cavity morphology of the tadpoles of eight species of Hypsiboas in the H. albopunctatus, H. faber, H. punctatus and H. pulchellus species groups. After a review of the available information about larval external and oral cavity morphology, no character state seems to be synapomorphic for Hypsiboas. The presence of a fleshy projection in the inner margin of the nostrils and rounded vacuities of the anteromedial surface of the choanae (pending the confirmation of the latter in Hyloscirtus and Myersiohyla) seems to be synapomorphic for the tribe Cophomantini, as previously noticed by other authors. Some putative synapomorphies are suggested for some species groups of Hypsiboas, but a denser sampling is needed to study the taxonomic distribution of these character states, in order to determine which clades they may support. The presence of lateral flaps with labial teeth in the oral disc is a variable feature of many species in the H. faber and H. pulchellus groups. A spiracular tube free from the body wall is present in some species, mostly in the H. albopunctatus group, but also in the H. rufitelus, H. faber and H. pulchellus groups. Unique ventrolateral cumules of neuromasts are present in H. faber, and also in some species of other groups of Hypsiboas and of the sister genus Aplastodiscus. Our results highlight the importance of studying the taxonomic distribution of many character states that were sometimes overlooked in tadpole descriptions but seem relevant to test phylogenetic hypothesis.

Fritz, U., Alcalde, L., Vargas‐Ramírez, M., Goode, E.V., Fabius‐Turoblin, D.U. & Praschag, P. (2012). Northern genetic richness and southern purity, but just one species in the Chelonoidis chilensis complex. —Zoologica Scripta, 41, 220–232. The Chelonoidis chilensis complex, the sister group of the famous Galápagos tortoises, is a widely distributed group of South American land tortoises, ranging from the dry Chaco of Bolivia, Paraguay and northern Argentina to northern Patagonia. Within this complex, up to three distinct species have been recognized. Using sequence data of the mitochondrial cytochrome b gene and length polymorphisms of 10 microsatellite loci, we investigate genetic differentiation among all three nominal species. We find only negligible differentiation, with decreasing genetic diversity from north to south. We conclude that only one species, Chelonoidis chilensis (Gray, 1870), is valid, with C. donosobarrosi (Freiberg, 1973) and C. petersi (Freiberg, 1973) as its junior synonyms. Morphological variation within C. chilensis sensu lato is in accord with the observation that size variation in chelonians follows Bergmann’s rule, with body size increasing with latitude. The observed phylogeographic differentiation inverses the well‐known pattern of southern genetic richness and northern purity from the northern hemisphere, resulting from dispersal from glacial refugia. This implies that in higher latitudes of both hemispheres genetic diversity may decrease with increasing distance from the refugium. For C. chilensis sensu lato, it seems likely that long‐distance dispersal via rafting on the Desaguadero River led to the foundation of the southernmost populations in northern Patagonia during the Holocene.

Stomach contents were obtained from 25 Hydromedusa tectifera and 47 Phrynops hilarii that live in syntopy in a pampasic stream in Buenos Aires province, Argentina. Both species are arthropod consumers. Copepods, ostracods, and hemipterans are the preferred items for P. hilarii, and H. tectifera prefers copepods, ostracods, immature dipterans (mainly chironomids), and ephemeropteran larvae. Items that most contribute to the diet of both species are immature chironomids, corixids, and belostomatids. Available food varies little among seasons, being slightly lower in winter months and part of the summer. Diet diversity changes by seasonal variation of prey item abundance in the diet of both species. Diet diversity is higher for P. hilarii (more generalist and broader trophic niche) than in H. tectifera, but there is no niche overlap between them. No significant correlation between the size of turtles and length of prey items was found. There is no evidence that the long neck of H. tectifera relates to piscivorous habits, because fish are a small fraction of its diet and arthropods constitute the bulk of the ingested items.