Teresa Cristina Sauer Avila-Pires

Niche segregation among sympatric Amazonian teiid lizards

Abstract We examined standard niche axes (time, place, and food) for three sympatric teiid lizards in the Amazon rain forest. Activity times during the day were similar among species. Ameiva ameiva were in more open microhabitats and had higher body temperatures compared with the two species of Kentropyx. Microhabitat overlaps were low and not significantly different from simulations based on Monte Carlo analysis. Grasshoppers, crickets, and spiders were important in the diets of all three species and many relatively abundant prey were infrequently eaten (e.g., ants). Dietary overlaps were most similar between the two species of Kentropyx even though microhabitat overlaps were relatively low. A Monte Carlo analysis on prey types revealed that dietary overlaps were higher at all ranks than simulated overlaps indicating that use of prey is not random. Although prey size was correlated with lizard body size, there were no species differences in adjusted prey size. A. ameiva ate more prey items at a given body size than either species of Kentropyx. Body size varies among species, with A. ameiva being the largest and K. altamazonica the smallest. The two species of Kentropyx are most distant morphologically, with A. ameiva intermediate. The most distant species morphologically are the most similar in terms of prey types. A morphological analysis including 15 species from four genera revealed patterns of covariation that reflected phylogenetic affinities (i.e., taxonomic patterns are evident). A cluster analysis revealed that A. ameiva, K. pelviceps, and K. altamazonica were in the same morphological group and that within that group, A. ameiva differed from the rest of the species. In addition, K. pelviceps and K. altamazonica were distinguishable from other species of Kentropyx based on morphology.

Evaluating the Effectiveness of Herpetofaunal Sampling Techniques across a Gradient of Habitat Change in a Tropical Forest Landscape

Abstract To improve our understanding of the distribution and abundance of amphibians and reptiles in tropical forests, herpetologists need to understand the relative effectiveness of different sampling techniques. However, current studies are biased by a focus on certain methods, species groups, or geographic regions. To address this problem, we conducted the first standardized comparison of patterns of species richness, rank-abundance, and community structure for both passive and active sampling methods for the study of herpetofauna in a tropical forest landscape. Moreover, we compare the effectiveness of these methods in primary and secondary forests and Eucalyptus plantation. Although different methods captured significantly different numbers of species and individuals, almost all techniques provided complementary benefits for the sampling of both lizards and leaf litter amphibians. The use of a limited set of methods can severely bias our understanding of changes in amphibian and lizard community structure in response to large-scale habitat change. Contrary to other studies, we recommend the use of pitfall traps in all studies, even Rapid Assessments (RAP), because they are indispensable for sampling many cryptic species, as well as being particularly cost effective for large-scale research. Because of the combination of complementary methods in sampling effectiveness, and the influence of method choice on taxon responses to habitat change, we recommend the use of multiple sampling techniques wherever possible. Synchronous adoption of multiple techniques in field studies will help improve sample representation and, thus, the understanding of species distributions and human impacts on herpetofauna in tropical forests.

Comparative Ecology of Sympatric Gonatodes (Squamata: Gekkonidae) in the Western Amazon of Brazil

Abstract Two sphaerodactyline geckos, Gonatodes hasemani and G. humeralis were studied in eastern Rondônia, Brazil, to determine ecological factors allowing coexistence. Gonatodes hasemani lives primarily on fallen logs in undisturbed forest, whereas G. humeralis lives primarily on tree trunks. Although both species occur in most forest patches, G. hasemani is more common within terra firme (never flooded) forest, and G. humeralis is more common in forest adjacent to rivers. Gonatodes hasemani is slightly larger in body size and is more robust than the more arboreal G. humeralis. Both species are active at the same time during the day, maintain the same body temperatures, and are most frequently found in shade. Dietary overlaps based on numbers (0.831) and volumes (0.877) of prey types were high indicating relatively similar diets. Differences in prey types appear to reflect differences in microhabitat use, and both species eat prey of the same size. Reproductive characteristics are similar but the larger bodied G. hasemani produces slightly larger eggs. The niche axis on which these two lizards most clearly separate is microhabitat: G. hasemani uses lower perches with larger diameters in the forest primarily because individuals typically are found on fallen logs, whereas G. humeralis uses higher and thinner perches because individuals are typically found on tree trunks and vines. Limited data on snakes that prey on small lizards in Amazon forest suggests the possibility that niche differences between these Gonatodes species may be mediated by predators. Dois lagartos geconídeos Sphaerodactylinae, Gonatodes hasemani e G. humeralis, foram estudados no leste de Rondônia, Brasil, com o intuito de se determinar os fatores ecológicos que permitem sua coexistência. Gonatodes hasemani vive primariamente sobre troncos de árvores caídos, em mata não perturbada, enquanto G. humeralis vive primariamente sobre troncos em pé. Embora ambas as espécies ocorram na maioria das áreas de mata, G. hasemani é mais comum em mata de terra firme, enquanto G. humeralis é mais comum em matas adjacentes a rios. Gonatodes hasemani é ligeiramente maior quanto ao tamanho do corpo e mais robusto que seu congênere mais arborícola, G. humeralis. Ambas as espécies estão ativas nas mesmas horas do dia, mantêm a mesma temperatura corporal, e são mais frequentemente encontradas na sombra. Uma grande sobreposição na dieta, tanto baseada em número (0.831) quanto em volume (0.877) de tipos de presas indica dietas relativamente similares. As diferenças observadas nos tipos de presas parecem refletir diferenças no uso de microhabitats, sendo o tamanho das presas semelhantes para as duas espécies. As características reprodutivas são semelhantes, mas G. hasemani, que possui um corpo maior, produz ovos ligeiramente maiores. O eixo no qual esses dois lagartos mais claramente se separam, no que diz respeito ao nicho, é o microhabitat: G. hasemani utiliza substratos mais baixos e de maior diâmetro na mata, primariamente porque indivíduos são tipicamente encontrados em troncos caídos, ao passo que G. humeralis utiliza substratos mais altos e mais finos, já que indivíduos são encontrados tipicamente sobre troncos de árvores vivas e cipós. Os dados, ainda que limitados, sobre cobras que se alimentam de pequenos lagartos na floresta amazônica sugerem a possibilidade de que as diferenças de nicho entre essas duas espécies de Gonatodes possam ser mediadas por predadores.

SMALL IN A BIG WORLD: ECOLOGY OF LEAF-LITTER GECKOS IN NEW WORLD TROPICAL FORESTS

Abstract We studied the ecology of four species of closely related leaf litter geckos, Coleodactylus amazonicus, C. septentrionalis, Lepidoblepharis xanthostigma, and Pseudogonatodes guianensis in tropical rainforests of Brazil and Nicaragua. All are found in leaf litter of undisturbed tropical forest where mean hourly surface temperatures vary from 23.5–29.1 C. Surface temperatures, where individual C. amazonicus were found, averaged 27.4 C and air averaged 29.9 C. Coleodactylus amazonicus was the smallest species and L. xanthostigma was the largest. The latter was the most different morphologically as well. Tail loss rates varied from 45.5–81.8% among species. All four species ate very small prey items, largely springtails, homopterans, termites, small insect larvae, and spiders. Nevertheless, considerable differences existed among species. Some variation existed among populations of C. amazonicus. Prey size was correlated with lizard SVL within and among species. All four species are typically the smallest species in their respective lizard assemblages. Small body size may have consequences for predation. Partially due to small body size, these lizards are vulnerable to extirpation resulting from effects of tree removal on thermal attributes of their leaf litter environment.

Life on the Leaf Litter: The Ecology of Anolis nitens tandai in the Brazilian Amazon

Abstract We studied the ecology of Anolis nitens tandai at three localities in the central and western Amazon of Brazil. The lizards were largely restricted to leaf litter microhabitats in relatively undisturbed rain forest. Activity occurred throughout the day. Body temperatures of active lizards averaged 27.7 ± 0.3 C and were similar to air and substratum temperatures in the microhabitats in which lizards were found. Microhabitats containing lizards were slightly warmer than a random set of microhabitats suggesting that the lizards selected relatively warm sites within a relatively cool forest habitat, but avoidance of treefalls suggests lizards do not seek out the warmest available microhabitats. The diet consisted mostly of grasshoppers, crickets, spiders, and insect larvae. Mean prey size increased with lizard body size, and lizards varied in how full their stomachs were. Sexual dimorphism in mass and limb length exists. Compared with other subspecies of Anolis nitens, A. n. tandai has relatively longer limbs than Anolis nitens scypheus or Anolis nitens nitens and intermediate body temperatures. Estudou-se a ecologia de Anolis nitens tandai em três localidades da Amazônia brasileira central e ocidental. Os referidos lagartos foram encontrados principalmente em microhabitats do folhiço, em floresta úmida relativamente não perturbada. Apresentaram-se ativos durante todo o dia, com uma temperatura corporal média de 27,7 ± 0,3 C, similar às temperaturas do ar e do substrato no microhabitat onde se encontravam. As temperaturas nos microhabitats contendo lagartos mostrou-se ligeiramente mais elevada que a de uma amostra aleatória de microhabitats, sugerindo que os lagartos procuram locais relativamente quentes em meio a um habitat florestal relativamente frio. Contudo, o fato de que evitam clareiras causadas pela queda de árvores sugere que eles não procuram os microhabitats mais quentes disponíveis. Dimorfismo sexual quanto à massa corporal e comprimento dos membros locomotores existe. A dieta consistiu principalmente de gafanhotos, grilos, aranhas e larvas de insetos. O tamanho médio da presa aumentou com o tamanho do corpo do lagarto, e os lagartos variaram com relação à quantidade de alimento encontrada nos estômagos. Em comparação a outras subespécies de Anolis nitens, A. n. tandai apresenta membros locomotores relativamente mais longos que Anolis nitens scypheus ou Anolis nitens nitens, e temperaturas corporais intermediárias.

Ecology of Two Sympatric Species of Neusticurus (Sauria: Gymnophthalmidae) in the Western Amazon of Brazil

Neusticurus ecpleopus is linearly distributed along forest streams, uses stream banks and associated leaf litter, and numerically feeds primarily on fly larvae and ants. The most important prey items volumetrically are crickets and fly larvae. Neusticurus juruazensis occurs in leaf litter of damp low forest but is not directly associated with streams. Fly larvae and collembolans are the most abundant items in the diet but orthopterans, centipedes, and fly larvae are the most important items based on volume. Activity patterns and body temperatures are similar between species, and temperatures of lizards and their microenvironments are higher than average environmental temperatures based on comparisons with null temperature distributions. Morphologically, N. ecpleopus is a more robust species with a relatively longer tail when compared with N. juruazensis. Sexual dimorphism in size and head proportions exists in N. juruazensis but not in N. ecpleopus, at least at our study site. Associations between morphology and habitat use suggest that differences in habitat use explain relatively minor dietary differences and allow coexistence. A comparison of several species and populations of Neusticurus indicates that ecologically there is very little variation among most species. Neusticurus ecpleopus distribui-se linearmente ao longo de riachos na mata, utiliza as margens dos riachos e o folhiCo associado, e alimenta primariamente, em termos numericos, de larvas de moscas e formigas. Em termos volumetricos, os itens predados mais importantes sio gafanhotos e larvas de moscas. Neusticurus juruazensis ocurre no folhipo da mata baixa e encharcada, mas nio esti diretamente associado a riachos. Larvas de moscas e colembolas sio os itens mais abundantes na dieta, mas ort6pteros, centropeias e larvas de moscas sio os itens mais importantes em termos de volume. Os padrtes de atividade e as temperaturas corporais sio semelhantes entre as duas especies. As temperaturas dos lagartos e de seus microambientes sio mais altas do que a media das temperaturas ambientais baseadas em comparap6es com distribup6es nulas de temperaturas. Morfologicamente, N. ecpleopus e uma especies mais robusta e com cauda relativamente mais longa do que N. juruazensis. Diformismo sexual quanto ao tamanho e quanto as proporytes da cabeca ocurrem em N. juruazensis, mas nio em N. ecpleopus, pelo menos em nossa Area de estudo. Associap6es entre morfologia e uso de habitat sugerem que diferencas no uso do habitat explicam pequenas diferenCas na dieta e permitem a coexistencia das duas especies. Uma comparaCio entre diversas especies e populap6es de Neusticurus indica que existe pouca variap o, ecologicamente entre as especies.

Sharing Amazonian Rain-Forest Trees: Ecology of Anolis punctatus and Anolis transversalis (Squamata: Polychrotidae)

Abstract We studied the ecology of Anolis punctatus and Anolis transversalis at six localities in the Amazon region of Ecuador and Brazil from 1994–1999. Both lizards are arboreal, about the same size (A. punctatus slightly larger) but differ in some body proportions. Anolis transversalis is restricted to undisturbed primary forest more so than A. punctatus, but both use similar microhabitats. During midday, A. transversalis was not observed, suggesting that individuals may not be active near the ground at that time. Both species are thermal conformers although each was able to maintain Tb slightly higher than that of its perch. Most lizards contained prey, and, overall, a positive relationship existed between lizard body size (SVL) and mean prey volume. Volumetrically, A. punctatus ate mostly ants and orthopterans, whereas A. transversalis ate mostly roaches, beetles, and ants. Dietary overlaps were low (0.56). These two species can be considered “crown giants” among Amazonian anoles. Similar to many Amazonian rain-forest lizards, ecological traits of A. punctatus and A. transversalis render them likely candidates for local extinction when deforestation occurs.

Anolis chrysolepis Duméril and Bibron, 1837 (Squamata: Iguanidae), Revisited: Molecular Phylogeny and Taxonomy of the Anolis chrysolepis Species Group

Abstract The Anolis chrysolepis species group is distributed across the entire Amazon basin and currently consists of A. bombiceps and five subspecies of A. chrysolepis. These lizards are characterized by moderate size, relatively narrow digital pads, and a small dewlap that does not reach the axilla. We used the mitochondrial gene ND2 to estimate phylogenetic relationships among putative subspecies of A. chrysolepis and taxa previously hypothesized to be their close relatives. We also assessed the congruence between molecular and morphological datasets to evaluate the taxonomic status of group members. On the basis of the two datasets, we present a new taxonomy, elevating each putative subspecies of A. chrysolepis to species status. We provide new morphological diagnoses and new distributional data for each species.

New Lizard of the Genus Leposoma (Squamata, Gymnophthalmidae) from the Lower Rio Negro, Amazonas, Brazil

Abstract A new species of Leposoma is described from Ilha do Lago do Prato and Ilha do Açaí, Arquipélago das Anavilhanas, in the lower Rio Negro, state of Amazonas, Brazil. Like all members of the parietale group, it differs from all species of the scincoides group by having wider and shorter dorsal scales and ventrals arranged in regular longitudinal rows. It is further characterized by having conic granules on the sides of neck, three enlarged pairs of chin shields, absence of granules between superciliaries and supraoculars, a longer than wide interparietal with lateral margins almost parallel, 42–44 transverse dorsal rows (the highest number in Leposoma), gular scales small in 13–15 rows (less than 11 in other Leposoma), 30–33 scales around body, 26–27 ventrals, two preanal and four femoral pores on each side in males, one preanal and no femoral pores in females, 13–14 and 19–21 lamellae under finger IV and toe IV, respectively. The new species is sympatric with Leposoma guianense and Leposoma percarinatum and is more similar to the latter.

Description and Phylogenetic Relationships of a New Genus and Species of Lizard (Squamata, Gymnophthalmidae) from the Amazonian Rainforest of Northern Brazil

ABSTRACT Marinussaurus curupira, a new genus and species of Gymnophthalmidae lizard is described from Iranduba, state of Amazonas, Brazil. The genus is characterized by an elongate body; short and stout pentadactyl limbs; all digits clawed; single frontonasal; two prefrontals; absence of frontoparietals; interparietal and parietals forming a straight posterior margin, with interparietal shorter than parietals; distinctive ear opening and eyelid; few temporals; three pairs of chin shields; nasal divided; a distinct collar; smooth, mainly hexagonal, dorsal scales; smooth quadrangular ventral scales; two precloacal and three femoral pores on each side in males; pores between three or four scales. Parsimony (PAR) and partitioned Bayesian (BA) phylogenetic analyses with morphological and molecular data recovered the new genus as a member of the Ecpleopodini radiation of the Cercosaurinae. A close relationship of the new genus with Arthrosaura is postulated.