Darío Cardozo

Chromosome Evolution in Dendropsophini (Amphibia, Anura, Hylinae)

Dendropsophini is the most species-rich tribe within Hylidae with 234 described species. Although cytogenetic information is sparse, chromosome numbers and morphology have been considered as an important character system for systematic inferences in this group. Using a diversity of standard and molecular techniques, we describe the previously unknown karyotypes of the genera Xenohyla, Scarthyla and Sphaenorhynchus and provide new information on Dendropsophus and Lysapsus. Our results reveal significant karyotype diversity among Dendropsophini, with diploid chromosome numbers ranging from 2n = 22 in S. goinorum, 2n = 24 in Lysapsus, Scinax, Xenohyla, and almost all species of Sphaenorhynchus and Pseudis, 2n = 26 in S.carneus, 2n = 28 in P.cardosoi, to 2n = 30 in all known Dendropsophus species. Although nucleolar organizer regions (NORs) and C-banding patterns show a high degree of variability, NOR positions in 2n = 22, 24 and 28 karyotypes and C-banding patterns in Lysapsus and Pseudis are informative cytological markers. Interstitial telomeric sequences reveal a diploid number reduction from 24 to 22 in Scarthyla by a chromosome fusion event. The diploid number of X.truncata corroborates the character state of 2n = 30 as a synapomorphy of Dendropsophus.

Taxonomic status of Pseudopaludicola riopiedadensis Mercadal de Barrio and Barrio, 1994 (Anura, Leptodactylidae, Leiuperinae).

Pseudopaludicola riopiedadensis was described by Mercadal de Barrio and Barrio (1994) based on two adult females collected by Luiz Dino Vizotto in 1963 from Rio Piedade, São José do Rio Preto, São Paulo, Brazil. This taxon was differentiated from P. ternetzi based on a series of qualitative and morphometric characters. Nevertheless, the original description and the type material of P. ternetzi were not considered by Mercadal de Barrio and Barrio, and the morphological variation of P. ternetzi was not documented. This work reviews the sample collected by Vizotto in P. riopiedadensis type locality, evaluates the advertisement calls obtained from such population, the two vouchers assigned to P. riopiedadensis, and a large data set, including type specimens of P. ternetzi to document the morphological variation along its known distribution. Results indicate that P. riopiedadensis was described on the basis of highly variable characters applied to a small sample and share the unique P. ternetzi autapomorphy, a robust body structure with immaculate belly. The lack of differentiation in both advertisement call and morphology rejects the status of P. riopiedadensis as distinct species, and we therefore suggest to formally consider P. riopiedadensis as junior synonym of P. ternetzi.

Description and Phylogenetic Position of a New Species of Oreobates (Anura: Craugastoridae) from Northwestern Argentina

Abstract:  We describe a new species of Oreobates from Jujuy, Argentina. The new species is clearly diagnosable from other species of Oreobates by a combination of morphological characters and support by molecular evidence (genetic distance and phylogenetic analysis). We also provide taxonomic comments about O. discoidalis and O. barituensis, emphasizing the need for an exhaustive revision of these species.

Cytogenetic characterization and B chromosome diversity in direct-developing frogs of the genus Oreobates (Brachycephaloidea, Craugastoridae)

Abstract Oreobates Jiménez de la Espada, 1872 is a large group of South American frogs with terrestrial reproduction and direct development, located in the superfamily Brachycephaloidea. About 260 brachycephaloidean species have been cytogenetically studied so far, at least with standard techniques. However, this information represents fewer than 17% species of the family Craugastoridae Hedges, Duellman & Heinicke, 2008, where the genus Oreobates is included. In the present work, using a diversity of standard and molecular techniques, we describe the karyotype of Oreobates barituensis Vaira & Ferrari, 2008, Oreobates berdemenos Pereyra, Cardozo, Baldo & Baldo, 2014 and Oreobates discoidalis (Peracca, 1895), from northwestern Argentina. The three species analyzed showed a diploid karyotype with 2n = 22 biarmed chromosomes, fundamental number (FN) = 44, nucleolus organizer regions (NORs) located pericentromerically on pair 7, and a centromeric and pericentromeric C-banding pattern. We observed variations in the chromosome number in Oreobates barituensis due the presence of two morphs of B chromosomes, one medium-sized telocentric (BT) and another subtelocentric and smaller (Bst). Both B chromosomes are mitotically stable and were recorded in all somatic and germinal cells analyzed. The BT chromosome occurred at a maximum of one per individual (2n = 22+BT), and the other one was observed single (2n = 22 + Bst) or as a pair in two doses (2n = 22 + 2BT). We additionally observed other supernumerary chromosomes in the three species analyzed, all of them euchromatic, small, dot-shaped and with instability during mitoses, showing a frequency of occurrence below 50% in studied specimens. The occurrence of polymorphic and spontaneous chromosomal rearrangements and supernumerary chromosomes is a recurrent feature reported in frogs with terrestrial habits (Brachycephaloidea and Hemiphractidae Peters, 1862), which suggests that Brachycephaloidea may be a promising group for studying the origin and maintenance of B chromosomes in anurans.

Chromosome evolution in Cophomantini (Amphibia, Anura, Hylinae)

The hylid tribe Cophomantini is a diverse clade of Neotropical treefrogs composed of the genera Aplastodiscus, Boana, Bokermannohyla, Hyloscirtus, and Myersiohyla. The phylogenetic relationships of Cophomantini have been comprehensively reviewed in the literature, providing a suitable framework for the study of chromosome evolution. Employing different banding techniques, we studied the chromosomes of 25 species of Boana and 3 of Hyloscirtus; thus providing, for the first time, data for Hyloscirtus and for 15 species of Boana. Most species showed karyotypes with 2n = 2x = 24 chromosomes; some species of the B. albopunctata group have 2n = 2x = 22, and H. alytolylax has 2n = 2x = 20. Karyotypes are all bi-armed in most species presented, with the exception of H. larinopygion (FN = 46) and H. alytolylax (FN = 38), with karyotypes that have a single pair of small telocentric chromosomes. In most species of Boana, NORs are observed in a single pair of chromosomes, mostly in the small chromosomes, although in some species of the B. albopunctata, B. pulchella, and B. semilineata groups, this marker occurs on the larger pairs 8, 1, and 7, respectively. In Hyloscirtus, NOR position differs in the three studied species: H. alytolylax (4p), H. palmeri (4q), and H. larinopygion (1p). Heterochromatin is a variable marker that could provide valuable evidence, but it would be necesserary to understand the molecular composition of the C-bands that are observed in different species in order to test its putative homology. In H. alytolylax, a centromeric DAPI+ band was observed on one homologue of chromosome pair 2. The band was present in males but absent in females, providing evidence for an XX/XY sex determining system in this species. We review and discuss the importance of the different chromosome markers (NOR position, C-bands, and DAPI/CMA3 patterns) for their impact on the taxonomy and karyotype evolution in Cophomantini.

First record of the invasive Hemidactylus mabouia (Moreau de Jonnès, 1818) (Squamata, Gekkonidae), in the dry Chaco, Argentina

The invasive Hemidactylus mabouia (Moreau de Jonnès, 1818) is one of the most widespread introduced species of reptiles, being present in the New World at least 500 years ago. In this work, we report for the first time, the presence of the invasive gecko H. mabouia in the dry Chaco, a biogeographic region included in the Gran Chaco Sudamericano. We collected 3 individuals in an urban zone at Las Lomitas, Patiño department, Formosa Province, Argentina. This new record extends the distribution range of this introduced species by nearly 300 km (in a straight line) from Formosa city, the nearest point previously reported.

Multiple Sex Chromosome System and Robertsonian Rearrangements Involved in the Chromosome Evolution of the Phymaturus palluma group (Iguania: Liolaemidae)

Abstract The Liolaemid genus Phymaturus is a clade of saxicolous lizards with 44 species recognized, grouped in the Phymaturus palluma and the Phymaturus patagonicus groups. The chromosome data about this genus are extremely scarce; however, unpublished evidence suggests a great karyotypic diversity, mainly in the P. palluma group. In this work, we describe the karyotypes of six species of the P. palluma group (one of them unnamed) and report a multiple chromosome sex determination system with heterogametic males (X1X1X2X2 / X1X2Y). This sex-system represents a putative synapomorphy for the group. In accordance with the published literature and data obtained in this study, we report a wide variability for the diploid number of the P. palluma group (2N = 26 to 36) but same autosomic fundamental number in all the species of the clade (FNa = 32). Such variation is a consequence of different numbers of telocentric macroautosome pairs among karyotypes (2 to 10), suggesting chromosomal evolution of the group, driven mainly by successive Robertsonian rearrangements.