The karyotype of three Brazilian Terrarana frogs (Amphibia, Anura) with evidence of a new Barycholos species

A recent substantial rearrangement of the 882 described eleutherodactyline frog species has considerably improved the understanding of their systematics. Nevertheless, many taxonomic aspects of the South American eleutherodactyline species remain unknown and require further investigation using morphological, cytogenetic and molecular approaches. In this work, the karyotypes of the Brazilian species Ischnocnema juipoca (Atibaia and Campos do Jordão, SP), Barycholos cf. ternetzi (Uberlândia, MG, and Porto Nacional, TO), and Pristimantis crepitans (Chapada dos Guimarães and São Vicente, MT) were analyzed using Giemsa staining, Ag-NOR labeling, and C-banding techniques. All individuals had a diploid number of 22 chromosomes, but the Fundamental Numbers were different among species. The herein described low chromosome number of Pristimantis crepitans is unique within this genus, suggesting that cytogenetically this species is not closely related either to its congeneric species or to Ischnocnema. In addition, karyotype differences, mainly in the NOR position, clearly distinguished the two Barycholos populations, besides indicating the existence of a so far undescribed species in this genus. A taxonomic review could clarify the systematic position of P. crepitans and verify the hypothetic new Barycholos species.

Cytogenetics of Hylodes and Crossodactylus species (Anura, Leptodactylidae) with comments on Hylodinae/Dendrobatidae relationships.

The karyotype, nucleolar organizer region (NOR) location and C-banding pattern of two species of Hylodes (H. phyllodes and H. asper) and two of Crossodactylus (Crossodactylus sp. n. and Crossodactylus cf. caramaschi) were studied. All species had a diploid number of 2n = 26, with differences in the chromosomal morphology of the Hylodes species while the two Crossodactylus species were cytogenetically indistinguishable. The NOR was located on pair 1 in both species of Hylodes, and on pair 8 in the Crossodactylus species. In the latter, the NOR was heteromorphic between the homologues. The NOR was coincident with a secondary constriction in the four species. Except to H. phyllodes, such secondary constrictions were clearly seen strongly stained after C-banding treatment. The C-banding pattern varied between the two species of Hylodes, but was identical in the Crossodactylus species. The results from conventionally stained karyotypes confirmed the uniformity within the genus Crossodactylus, and the relatively conserved karyotypes within Hylodes, in agreement with other literature reports. We conclude that the cytogenetic data do not provide further evidence which could be useful to corroborate the supposed relationships between the hylodines and dendrobatids since there are no unambiguous homeologies between the karyotypes of these groups.

The ultrastructure of the spermatozoa of Epipedobates flavopictus (Amphibia, Anura, Dendrobatidae), with comments on its evolutionary significance.

We describe, for the first time, the spermatozoon ultrastructure of a dendrobatid frog, Epipedobates flavopictus. Mature spermatozoa of E. flavopictus are filiform, with a moderately curved head and a proportionally short tail. The acrosomal vesicle is a conical structure that covers the nucleus for a considerable distance. A homogeneous subacrosomal cone lies between the acrosome vesicle and the nucleus. The nucleus contains a nuclear space at its anterior end, and electron-lucent spaces and inclusions. No perforatorium is present. In the midpiece, the proximal centriole is housed inside a deep nuclear fossa. Mitochondria are scattered around the posterior end of the nucleus and inside the undulating membrane in the anterior portion of the tail. In transverse section the tail is formed by an U-shaped axial fiber connected to the axoneme through an axial sheath, which supports the undulating membrane. The juxta-axonemal fiber is absent. The spermatozoon of E. flavopictus has several characteristics not observed before in any anurans, such as a curved axial fiber, absence of a juxta-axonemal fiber, and presence of mitochondria in the typical undulating membrane. Our results endorse the view that, in anurans, the conical perforatorium and subacrosomal cone are homologous and that Dendrobatidae should be grouped within Bufonoidea rather than Ranoidea.