The spermatozoon of Iguana iguana is filiform and resembles that of other iguanian lizards, being most similar to Tropidurus . All sperm synapomorphies of Tetrapoda, Amniota and Squamata are present in the sperm of Iguana iguana . By reconstructing the evolution of 30 sperm characters we identified a novel synapomorphy of Iguania: the presence of a well-developed acrosomal ridge at the level of the epinuclear lucent zone. Because of the poor topological resolution among iguanian clades we could not discount the possibility of convergence or neutral selection as determinant of the variability in characteristics of the sperm cell. In agreement with previous studies, we identified heterogeneous rates of evolution among the three main regions of the sperm cell, namely the head, midpiece and tail.

A detailed description of the sperm ultrastructure of Tropidurus semitaeniatus and T. torquatus is provided. Mature spermatozoa of T. semitaeniatus and T. torquatus are filiform and characterized by: apical portion of acrosome depressed; perforatorium single; epinuclear lucent zone well developed; midpiece short; mitochondria columnar; midpiece with three sets of alternating ring structures and mitochondria (rs1/m1, rs2/m2, rs3/m3); nuclear shoulders rounded; nucleus elongate; fibres 3 and 8 enlarged; and fibrous sheath in midpiece. Spermatozoa ofTropidurus are unusual in possessing a unilateral electron-lucent ridge at the surface of the acrosome and an epinuclear electron-lucent zone. The two species are very similar, differing in details such as degree of acrosome flattening, presence of bulging at nuclear base, and arrangement of microtubules in the endpiece. Comparisons between Tropiduridae and other families of iguanian lizards are made.

Phylogenetic relationships of corytophanid lizards (Iguania, Squamata, Reptilia) based on partitioned and total evidence analyses of sperm morphology, gross morphology, and DNA data. -Zoologica Scripta , 34 , 605-625. We conducted partitioned and combined Bayesian and parsimony phylogenetic analyses of corytophanid lizards (Iguania) using mtDNA, gross morphology, and sperm ultrastructure data sets. Bayesian and parsimony hypotheses showed little disagreement. The combined analysis, but not any of the partitioned ones, showed strong support for the monophyly of Corytophanidae and its three genera, Basiliscus , Corytophanes , and Laemanctus . Basiliscus is the sister taxon of a well-supported clade formed by Corytophanes and Laemanctus . The relationships of species within Basiliscus and Corytophanes received weak support, regardless of the method used. We defend those relationships as feasible and open to further testing. Data derived from the ultrastructure of spermatozoa are potentially a good source of characters for systematic inferences of Iguania and its major lineages. A Brooks Parsimony Analysis based on the geographic distributions of corytophanids and the phylogenetic tree obtained from the combined analysis suggested a Central American origin of the group, a recent colonization of northern South America, and the role of epeirogenic uplifts and the formation of lowlands during the late Tertiary in the differentiation of corytophanids.

No abstract

ABSTRACT. Life history parameters such as diet, reproduction, and sexual dimorphism are crucial to understand ecological and evolutionary forces shaping species traits. Nevertheless, such information is scant in the literature for most Neotropical squamates. Gymnophthalmidae contains over 242 species in 46 genera and includes small-size, mostly terrestrial species, although psamophilic, semi-aquatic, and low vegetation dwellers also occur. Dryadosaura is a monospecific genus -Dryadosaura nordestina Rodrigues et al., 2005 -, occurring in Atlantic Forest areas from Rio Grande do Norte to Northern Bahia, and little is known about its ecology and natural history. We analyzed the species' diet, reproduction, and sexual dimorphism based on 170 specimens deposited in museum collections. Dryadosaura nordestina is considered generalist and active forager, based on dietary items. Arthropods, especially ants and insect larvae, dominate the diet. The reproductive period shows a peak during the rainy season (May through June), while recruitment occurs from July through November. Males are significantly larger than females, and sexes can also be distinguished based on shape variables: males have higher heads and longer bodies, while body height and width are larger in females.

We investigate the role of ecology and phylogeny in the association between lizard abundance and microhabitat variables in an Amazon rain forest site. Using pitfall trap arrays, we collected data from 349 individuals belonging to 23 lizard species. After accounting for spatial autocorrelation and using a canonical correspondence analysis (CCA), we found that lizard captures were significantly associated with microhabitat variables, which accounted for 48 percent of the observed variation. Furthermore, a canonical phylogenetic ordination (CPO) indicated that microhabitat variables are more important in determining the distribution of lizard species than phylogenetic relationships among species. Termite nests, canopy openness, and tree circumference were strongly associated with the number of captures of certain lizard species. Our results confirm autecology studies of individual lizard species for which data are available. We suggest that maintaining heterogeneous forested microhabitats should be a central goal for sustaining a high lizard biodiversity in Amazon rain forests.Abstract in Portuguese is available in the online version of this article.

We tested three non-exclusive hypotheses that the lizard, Gymnodactylus carvalhoi, lives in termitaria to avoid thermal extremes, to avoid predators, or because of an abundance of food (dietary specialist). We first confirm that these geckos are restricted to termitaria in the region studied. Body temperatures (T b ) of geckos averaged below environmental temperatures during day outside of termitaria and above outside temperatures at night; T b averaged only slightly higher than temperatures inside termitaria. We conclude that thermal constraints in Cerrado habitats lacking rocks restrict Gymnodactylus to termite nests. High frequencies of tail loss and the presence of many potential predators within termitaria suggest high encounter rates with predators, indicating that predation pressure does not restrict these geckos to termite nests. Dietary data indicate that G. carvalhoi is a termite specialist. Published data indicate that other Gymnodactylus species and populations are also termite specialists, even though several live primarily outside termitaria (in crevices and under rocks). An evolutionary history of termite specialization and low thermal requirements in the clade (Gymnodactylus) predispose them to feed on termites within the termitaria.

No abstract