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.

We studied the oral apparatus, buccal cavity and musculoskeletal features in tadpoles of five species of the genus Scinax (S. acuminatus, S. uruguayus, S. aff. pinima, S. aromothyella, and S. berthae). Observed variation is mainly related to intrageneric grouping. Scinax acuminatus (S. ruber clade, sister taxon of S. rostratus group) has a distinctive combination of a mental gap in the margin of oral papillae, straight labial teeth with few or absent cusps, processus muscularis acute and posteriorly directed, and m. subarcualis rectus I with two slips. Scinax uruguayus and S. aff. pinima (S. uruguayus group) have keratinized sheets ventrolateral to the lower jaw sheath, well-developed infralabial and lateral ridge papillae, robust jaw cartilages, cornua trabeculae with short and widely divergent free portions, processus articularis short and wide, processus muscularis thin and directed anteriorly. Scinax aromothyella and S. berthae (S. catharinae group) have poorly developed, non-colored spurs behind the lower jaw sheath, long and thin processus articularis, wide and rounded processus muscularis, and tripartite cartilago suprarostralis. Anatomical features described are congruent with current phylogenetic arrangements based on molecular, chromosomal, and morphological data, and provide a source of information that can be useful to solve interspecific relationships within Scinax.

Natale, G.S., Alcalde, L., Herrera, R., Cajade, R., Schaefer, E.F., Marangoni, F. and Trudeau, V.L. 2011. Underwater acoustic communication in the macrophagic carnivorous larvae of Ceratophrys ornata (Anura: Ceratophryidae). -Acta Zoologica (Stockholm) 92: 46-53.We provide the first evidence for sound production by anuran larvae. In this study, we describe the sounds, their context-specific emission and the structures related to sound production of the carnivorous larvae of Ceratophrys ornata (Amphibia, Anura, Ceratophryidae). Tadpoles emit a brief, clear and very audible metallic-like sound that consists of a short train of notes that occur at all stages of larval development. Tadpoles make sound only when a conspecific tadpole is preying upon it or when touched by an object. Ceratophrys ornata larvae possess the basic required anatomical structures for sound production via expulsion of atmospheric air from the lungs through the open soft-tissue glottis. The glottis is opened and closed via the larval laryngeal muscles (constrictor laryngis and dilatator laryngis). The arytenoid cartilages appear at stage 40 and the cricoid cartilage does at stage 43. Adult laryngeal muscles differentiate from the larval ones at stage 46 together with the vocal sac formation from the adult interhyoideus muscle. We demonstrate (n = 2160 conspecific predator-prey interactions) that larval sounds occur always under predatory attack, probably serving to diminish the chances of cannibalism. These data raise the possibility that other macrophagic carnivorous anuran larvae may produce sound.

Anurans employ a wide variety of anti‐predator mechanisms to defend themselves. In casque‐headed hylids, defence is thought to be a complex combination of several anti‐predator mechanisms. However, the defence traits of only a few species are known; some hypotheses have yet to be addressed, whereas others, already tested in some species, need to be tested in additional taxa. The anti‐predator mechanism of the casque‐headed frog, Argenteohyla siemersi, is described here. It is a complex mechanism consisting of (1) behavioural and ecological traits, including secretive and semi‐phragmotic habits and posture; (2) morphological features, including cryptic and aposematic colourations, a skull covered with bony dermal spines and protuberances that are associated with two types of granular venom glands; and (3) physiological and chemical traits, such as a highly lethal skin secretion. Our results are compared with those of previous studies of defence mechanisms in casque‐headed frogs in an effort to understand the mechanisms and evaluate their potential phylogenetic signal in this group of anurans.

Knowledge of parasites in turtles is scarce, particularly with regard to freshwater turtles of South America. Here, we describe the association of Spiroxys contortus (Rudolphi, 1819)in Phrynops hilarii (Duméril & Bibron, 1835) and S. contortus and Hedruris orestiae (Moniez, 1889) in Hydromedusa tectifera (Cope, 1870). The presence of S. contortus in P. hilarii represents a new host record and also the southernmost geographic record for this species. More interestingly, the presence of H. orestiae in H. tectifera represents the first record of this helminth species from a reptilian host.