Gustavo H. C. Vieira

The ultrastructure of the spermatozoon of the lizard Iguana iguana (Reptilia, Squamata, Iguanidae) and the variability of sperm morphology among iguanian lizards

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 CRITICALLY ENDANGERED NEW SPECIES OF CNEMIDOPHORUS (SQUAMATA, TEIIDAE) FROM A CERRADO ENCLAVE IN SOUTHWESTERN AMAZONIA, BRAZIL

We describe a new species of Cnemidophorus from a Cerrado enclave in southwestern Amazonia, Rondônia state, Brazil. This species is apparently endemic to Cerrado enclaves in the vicinity of the city of Vilhena, a region under intensive anthropic pressure due to the expansion of soybean plantations. A discriminant analysis indicated that femoral pores and scales around the tail are the best discriminators among Brazilian species of Cnemidophorus. A naïve Bayesian network constructed with categorical (mostly coloration) variables indicated that the new species had high conditional probabilities of dorsolateral fields absent, vertebral field spotted, and paravertebral lines absent. The analyses revealed clear distinctions between species of Cnemidophorus that range north and south of the the Amazon River. The new species may have evolved as a result of vicariance, following the isolation of peripheral enclaves of Cerrado in southwestern Amazonia after the late Pleniglacial. The restricted range in small areas, under extreme human pressure around Vilhena, makes this species one of the most critically endangered elements of the Brazilian herpetofauna.

Ultrastructural study of spermatozoa of the neotropical lizards, Tropidurus semitaeniatus and Tropidurus torquatus (Squamata, Tropiduridae).

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

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.

Spermiogenesis and testicular cycle of the lizard Tropidurus torquatus (Squamata, Tropiduridae) in the Cerrado of central Brazil

We studied the spermiogenesis and testicular cycle of the lizard Tropidurus torquatus , using light and electron microscopy. Males bearing spermatozoa were present practically year-round and spermatogenic activity showed a regenerative phase from late dry season to the end of the rainy season (July to March), with low frequency of initial stages of the spermatogenic cycle, and a brief degenerative phase from April to June, lacking the total regression of seminiferous tubules. These characteristics resemble those from species with continuous reproductive cycles, contrasting with the strongly seasonal reproductive cycle of females. Spermiogenesis includes nuclear elongation, chromatin condensation, acrosomal and flagellar development, and elimination of excessive cytoplasm. We describe some new aspects in the spermiogenesis of T. torquatus , including the interaction between spermatid and Sertoli cell, acrosomal granule, subacrosomal granule, and the fibrous sheath formation. The testicular cycle of T. torquatus is very similar to that of other lizards that inhabit seasonal environments, and its spermiogenesis and ultrastructure of mature sperm display a number of conservative features.

Ecology of Anolis nitens brasiliensis in Cerrado Woodlands of Cantao

Abstract We studied the ecology of Anolis nitens brasiliensis during late-dry and early-wet season 2005 in a Cerrado habitat in Tocantins state, Brazil. Most lizards were found on tree trunks or leaf litter in non-flooded igapó forest. Most were found in shade or filtered sun on both cloudy and sunny days. Body temperatures (Tbs) averaged 30.6°C and did not vary among microhabitats. Microhabitats exposed to direct sun consistently reached extremely high temperatures whereas microhabitats in shade or filtered sun provided temperatures throughout the day allowing lizard activity. Nineteen prey categories were found in lizard stomachs, but the diet was dominated by spiders, crickets/grasshoppers, ants, and beetles. Although lizards that ate large prey ate fewer prey, no correlation existed between size or number of prey and lizard body size (SVL). Males were larger in SVL and mass than females, and males had relatively longer hind limbs than females. Females were variable but larger in body width. In general, the ecology of Anolis n. brasiliensis is similar to that of its Amazonian relatives, with the exception that it lives in a more thermally extreme environment and is active at slightly higher Tbs. Ecological traits of this lizard, particularly its reliance on relatively low Tb for activity, suggest that it might be particularly vulnerable to local extinction if its habitat is altered. The presence and apparent widespread distribution of A. n. brasiliensis in the Cerrado provides further evidence that the “vanishing refuge” theory cannot account for geographical patterns of distribution in the A. nitens complex.

Reproduction, Body Size, and Diet of Polychrus acutirostris (Squamata: Polychrotidae) in Two Contrasting Environments in Brazil

Abstract We compared reproduction, diet, and body size of Polychrus acutirostris (Squamata: Polychrotidae) from the Cerrado and Caatinga biomes in Brazil. Because these two biomes have widely different climates, we predicted that lizards in Caatinga would produce smaller clutches in response to rainfall unpredictability. We also expected reproductive timing to differ between biomes, with lizards occurring in the Cerrado producing a single clutch in association with the predictable rains of October–November. Contrary to expectations, clutches had fewer (although larger) eggs in Cerrado. Reproductive period was remarkably similar (peak of female reproductive activity in November), but female reproduction started 1 month earlier in Cerrado. Diet composition was also similar, with the exception of spiders, that exhibited a high index of relative importance in Cerrado but were nearly absent in Caatinga lizard diets. Lizards from both biomes ingested a large proportion of plant material, as well as soft-bodied arboreal arthropods, such as orthopterans, and mostly slow-moving, large arboreal insects. Rainfall predictability in the Cerrado therefore did not influence Polychrus reproduction or diet in the same manner as in other lizard species. The large number of small eggs in the Caatinga suggests that the competitive environment for offspring is either unpredictable or that mortality is high but random. Rain forest Polychrus lizards produce few large eggs, suggesting that the competitive environment for offspring is predictably intense and mortality is non-random. Cerrado Polychrus lizards seem intermediate between Caatinga and rain forest Polychrus lizards, producing fewer and larger eggs than their conspecifics in the Caatinga but relatively more and smaller eggs than rain forest Polychrus species.

An ultrastructural comparative study of the sperm of Hyla pseudopseudis, Scinax rostratus, and S. squalirostris (Amphibia: Anura: Hylidae)

We make detailed comparisons of the ultrastructure of the spermatozoon among three species of the family Hylidae, Hyla pseudopseudis, Scinax rostratus, and S. squalirostris. The acrosome complex consists of two conical structures covering the nuclear rostrum, the acrosome vesicle, and the subacrosomal cone. The nucleus has a moderately condensed chromatin with a conical shape in longitudinal sections and a circular shape in cross-sections. In H. pseudopseudis, mitochondria are numerous and circular, and in S. rostratus and S. squalirostris there are fewer mitochondria that are more elongate in longitudinal and transverse sections. In H. pseudopseudis, the mitochondrial collar starts adjacent to the distal centriole, occupying the whole midpiece, whereas in both Scinax species the mitochondrial collar starts only at the posterior one-third of the midpiece. In both Scinax species, the presence of juxta-axonemal fiber, axial sheath, and axial fiber in the tail are seemingly plesiomorphic characters, widespread among bufonoid frogs. In H. pseudopseudis, however, the absence of axial fiber and axial sheath seems to be derived from the typical bufonoid condition. The differences between Hyla and Scinax sperm endorse the separation of the two genera and suggest that sperm ultrastructure can be a useful tool to investigate relationships at the intrafamily level.

Herpetofauna of protected areas in the Caatinga III: The Catimbau National Park, Pernambuco, Brazil

Despite the increase in herpetofaunal inventories in the Caatinga biome, information for many areas is still lacking and new surveys are required. We conducted a 30-day inventory of the herpetofauna of the Catimbau National Park, Pernambuco State, Brazil. Thirty-seven pitfall trap arrays composed of 4 buckets each, along with glue traps and active searches were used to sample local herpetofaunal diversity. We recorded 21 species of frogs, 25 lizards, 11 snakes, and 1 chelonian. All sampling methods contributed significantly to achieve the amphibian and reptile diversity recovered in the inventory. Rarefaction curves and richness estimators suggest that local biodiversity is still underestimated. We attempted to show the great potential of Catimbau National Park, characterized by the richest herpetofauna surveyed in a core region of the biome, along with the presence of endemic species such as the worm snake Amphisbaena supranumeraria and the limbless lizard Scriptosaura catimbau, underscoring the importance of the area for the conservation and maintenance of the Caatinga herpetofauna biodiversity.