Sex chromosomes in the Vizcacheras' White-lipped frog, Leptodactylus bufonius (Anura, Leptodactylidae).

Cytogenetic analyses were performed on specimens of Leptodactylus bufonius from different localities in Argentina. Mitotic chromosomes were studied with Giemsa and differential staining techniques (Ag-NOR, C-banding, and CMA3/DAPI) and fluorescence in situ hybridization with the 18S DNAr probe. All specimens showed karyotypes with 2n = 2x = 22 and FN = 44. Secondary constrictions were present in the long arm of chromosome pair 8, coincident with Ag-NOR and hybridization signals of the 18S DNAr probe. The C-banding technique evidenced an important amount of heterochromatin with a sex-linked pericentromeric band in the short arm of chromosome pair 4. This heterochromatic band was heteromorphic in males but present in both homologues of females, and it was CMA3 positive (DAPI negative) at fluorescence staining. The occurrence of heteromorphic XY sex chromosomes in L. bufonius is the second known case in Leptodactylus and the fifth within the speciose family Leptodactylidae.

Chromosome evolution in Lophyohylini (Amphibia, Anura, Hylinae).

The hyline tribe Lophyohylini includes 87 species of treefrogs, of which cytogenetics aspects have been studied in less than 20% of them. In order to evaluate the evolution of some of its chromosome characters (NOR position, C-bands, and DAPI/CMA3 bands), we studied the karyotypes of 21 lophyohylines, 16 of them for the first time, and analyzed them in a phylogenetic context. Most species showed similar karyotypes regarding chromosome number (2n = 24) and morphology (FN = 48), excepting Phyllodytes edelmoi and Osteocephalus buckleyi with 2n = 22 (FN = 44) and 2n = 28 (FN = 50), respectively. The NOR location was variable among species and provided valuable phylogenetic information. This marker was located in pair 11 in all species of Trachycephalus, Itapotihyla langsdorffii, and Nyctimantis arapapa, representing the plesiomorphic condition of Lophyohylini. Besides, other apomorphic states were recovered for the clades comprising N. rugiceps and N. siemersi (NOR in pair 5), and Dryaderces pearsoni, Osteocephalus, and Osteopilus (NOR in pair 9). Phyllodytes presented variation for NORs position; they were in pair 2 in P. edelmoi, pair 7 in P. melanomystax, and pair 8 in P. gyrinaethes and P. praeceptor. Polymorphisms in size, number, and activity of this marker were observed for N. siemersi, Osteocephalus fuscifacies, and some species of Trachycephalus. Remarkably, in N. siemersi NORs were detected on a single chromosome in the two specimens studied by this technique, raising the question of how this complex polymorphism is maintained. Interstitial telomeric sequences were found in P. edelmoi, P. melanomystax, and Osteocephalus buckleyi, and their presence seems to be not related to the chromosome reorganization events. Finally, some species showed spontaneous rearrangements, possibly as a consequence of an uncommon phenomenon in anuran cytogenetics: the presence of fragile sites or secondary constrictions not associated with NORs. We propose that this rare feature would have played an important role in the evolution of this group of frogs. From the evidence obtained in this and previous studies, we conclude that Lophyohylini presents a complex chromosome evolution.

A new frog of the Leptodactylus fuscus species group (Anura: Leptodactylidae), endemic from the South American Gran Chaco.

A new species of Leptodactylus frog (Anura: Leptodactylidae) from the South American Gran Chaco, morphologically similar and previously confused with the widespread Leptodactylus mystacinus, is described through the use of multiple sources of evidence (molecular, external morphology, coloration, osteology, bioacoustics, and behavior). The phylogenetic analysis with partial sequences of mitochondrial rDNA genes (12S and 16S) recovered the new species within the L. fuscus group, being highly divergent (>3% genetic distance in 16S). The new species was recovered as sister taxa of L. mystacinus, from which it is distinguished by tympanum coloration, cephalic index, dorsum and legs coloration, and some osteological differences in nasals and prevomers. This new frog is characterized by a moderate body size (SVL 46.80-66.21 mm), distinctive color pattern (reddish dorsal surfaces of body with noticeable black stripes in the dorsolateral folds), a circular and dark tympanum with dark tympanic annuli, and behavior of males that call on top of fallen logs and tree branches close to the ground.

A new species of Physalaemus (Anura, Leptodactylidae) from the Atlantic Forest of Misiones, northeastern Argentina.

A new species of Physalaemus from Misiones province, Argentina, in the Atlantic forest domain is described. The new species is a member of the P. gracilis group, based on its phylogenetic position and the occurrence of a putative morphological synapomorphy (occurrence of an unpigmented median stripe on throat, chest, and/or abdomen). Physalaemus sp. nov. is characterized by a long advertisement call composed of non-pulsed notes with slightly descendant modulation, large size (mean SVL = 32.0 mm males, 34.0 mm females), slender body aspect, head longer than wide, supratympanic fold developed, an unpigmented median stripe on venter, medium sized inguinal glands, tarsal tubercle present, and supernumerary tubercles on hands and feet, which are character states that combined distinguish the new species from all the members of the genus. In this study, we provide its formal description based on external morphology, advertisement call, and 16S genetic distance. In addition, the distribution ranges for the new species and P. gracilis are revisited, the advertisement call of P. gracilis is redescribed, and a discussion about the available names which could be applicable to the new species is provided.

A new species of Pseudopaludicola (Anura, Leiuperinae) from Espírito Santo, Brazil.

We describe a new anuran species of the genus Pseudopaludicola that inhabits sandy areas in resting as associated to the Atlantic Forest biome in the state of Espírito Santo, Brazil. The new species is characterized by: SVL 11.7-14.6 mm in males, 14.0-16.7 mm in females; body slender; fingertips knobbed, with a central groove; hindlimbs short; abdominal fold complete; arytenoid cartilages wide; prepollex with base and two segments; prehallux with base and one segment; frontoparietal fontanelle partially exposed; advertisement call with one note composed of two isolated pulses per call; call dominant frequency ranging 4,380-4,884 Hz; diploid chromosome number 22; and Ag-NORs on 8q subterminal. In addition, its 16S rDNA sequence shows high genetic distances when compared to sequences of related species, which provides strong evidence that the new species is an independent lineage.

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.

Karyotypic Data on 28 Species of Scinax (Amphibia: Anura Hylidae) Diversity and Informative Variation

The hylid frog genus Scinax is the most species-rich within Hylinae, with more than 100 recognized species grouped in the S. catharinae and S. ruber clades. The karyotypes of 14 species of the S. catharinae clade and 14 of the S. ruber clade were analyzed, several of them for the first time. All studied species presented 2n  =  2x  =  24 biarmed chromosomes (FN  =  48) and no identifiable sex chromosomes. There are two alternate states associated with the size and morphology of pair 1, corresponding to the S. catharinae clade and to the S. ruber clade. The morphology of pairs 2 and 6 also differentiate the species of both major clades. Species of the S. ruber clade in general have Ag-NORs in pair 11, as is commonly observed among hylines with 2n  =  24. The Ag-NORs' position in the long arms of pair 11 is interstitial in S. fuscomarginatus, S. fuscovarius, S. nasicus, S. similis, S. squalirostris, and S. uruguayus, and terminal in S. acuminatus, S. curicica, S. duartei, S. granulatus, S. hayii, and S. perereca. The single exception among species of the S. ruber clade is S. alter, which has terminal Ag-NORs at the long arms of pair 3. Most species of the S. catharinae clade have Ag-NORs in pair 6, representing a putative synapomorphy of this clade, while the Ag-NORs in pair 11 that occur in S. canastrensis are most parsimoniously interpreted as a reversion. C-banding is predominantly centromeric, but in the S. catharinae clade there is a greater amount of heterochromatin than in the S. ruber clade. This study corroborates the occurrence of informative variation, some already considered in a previous cladistic analysis, and reports new characters, outlining the significance of cytogenetic data for the systematics of Scinax.