Ultrastructure variation in the spermatozoa ofPseudopaludicolafrogs (Amphibia, Anura, Leptodactylidae), with brief comments on its phylogenetic relevance

Abstract

The taxonomic history of the small frogs of the genus Pseudopaludicola from South America has been controversial. Phylogenetic inferences based on molecular data have identified four Pseudopaludicola clades, correlating with the known variation in karyotypes (2n = 22, 20, 18, and 16). In this study, the ultrastructure of the spermatozoa was analyzed in 12 species of the Pseudopaludicola, with the aim of describing their morphology and identifying characters that may contribute to a better understanding of the phylogenetic relationships. The spermatozoa presented marked differences in tail structures. The tails of the spermatozoa of the species with 2n = 22 chromosomes (Pseudopaludicola sp. 1 [P. pusilla group], Pseudopaludicola falcipes, P. mineira, and Pseudopaludicola saltica), as well as Pseudopaludicola ameghini and Pseudopaludicola ternetzi (2n=20), have juxta-axonemal fibers, undulating membranes and axial fibers. In contrast, in the species with 2n = 18 (P. facureae, P. giarettai, Pseudopaludicola canga, P. atragula, and Pseudopaludicola sp. 2) and 2n = 16 (Pseudopaludicola mystacalis), there are no evident axial or juxta-axonemal fibers, but a paraxonemal rod with a thick undulating membrane, which is shorter than that found among Pseudopaludicola species. The ultrastructural morphological differences observed in the spermatozoa of these species may be phylogenetically informative, given that they coincide with the consensus phylogeny of the group and appear to represent a progressive simplification of the spermatozoon.

A comparative ultrastructural analysis of spermatozoa in Pleurodema (Anura, Leptodactylidae, Leiuperinae)

“…J) and P. thaul (Pugin and Garrido, ). Also, this condition has recently been reported for several species Pseudopaludicola ( Pseudopaludicola canga , P. giarettai , P. atragula , P. facureae , and P. mystacalis ; Santos et al ). Occurrence of an abaxonemal bulb‐shaped swelling : (0) absent, (1) present.This structure also refers to the accessory fibers of the sperm tail. The paraxonemal rod can possess a distinct bulb at the abaxonemal end (character 7: 1).…”

“…Transverse striations observed at midpiece (character 1: 1) in Pleurodema guayapae were considered in this study as homologous to those described in all Physalaemus species studied at present ( P. biligonigerus , P. gracilis , P. marmoratus , and P. nattereri ) and in some Pseudopaludicola species ( P. ameghini , P. canga , P. falcipes , and P. saltica ; Amaral et al, ; Zieri et al, ; Santos et al, ).…”

“…The acrosome complex of the spermatozoa in most species of Pleurodema is formed by a subacrosomal cone below the acrosome vesicle, similarly to that observed in most studied hyloid frogs. This configuration was observed in Batrachylidae (Pugin and Garrido, ), Bufonidae (Burgos and Fawcett, ; Rastogi et al, ; Lee and Jamieson, ; Meyer et al, ; Báo et al, ), Calyptocephalellidae (Pugin and Garrido, ), Dendrobatidae (Garda et al, ; Aguiar‐Jr et al, 2003, 2004; Veiga‐Menoncello et al, ), Hylidae (Rastogi et al, ; Lee and Kwon, ; Lee and Jamieson, ; Costa et al, ), other Leptodactylidae (Amaral et al, ; Scheltinga, ; Zieri et al, ; Santos et al, ), Microhylidae (Scheltinga et al, ), Myobatrachidae (Lee and Jamieson, ), and Rhinodermatidae (Pugin and Garrido, ). The subacrosomal cone was also observed in Ascaphidae (Jamieson et al, ), Leiopelmatidae (Scheltinga et al, ), Pelodytidae (Pugin‐Ríos, ), Megophryidae, and Pelobatidae (Scheltinga, ).…”

“…Figure J.Characters 4–6 refer to the accessory fibers of the sperm tail. The generalized anuran sperm has two longitudinal fibers that accompany the axoneme: the juxtaxonemal fiber (= minor fibre sensu Lee and Jamieson, ) adjacent to doublet 3 of the axoneme, and the axial fiber (= major fibre sensu Lee and Jamieson, = axial rod sensu Amaral et al, ).An axial fiber occurs in Pseudopaludicola falcipes , P. mineira , P. saltica , and P. ternetzi (Amaral et al, ; Santos et al, ). In these cases, the axial fiber is attached to the juxtaxonemal fiber by a thin cytoplasmic lamina, the undulating membrane (characters 4:1; 5: 1, 6: 0).…”

“…An axial fiber occurs in Pseudopaludicola falcipes , P. mineira , P. saltica , and P. ternetzi (Amaral et al, ; Santos et al, ). In these cases, the axial fiber is attached to the juxtaxonemal fiber by a thin cytoplasmic lamina, the undulating membrane (characters 4:1; 5: 1, 6: 0).…”