Abstract We analyzed reproductive biology of Erythrolamprus jaegeri coralliventris, a snake from the Brazilian Pampa. Females presented larger snout-vent length than males, while no significant differences were found in tail length/snout-vent length ratios between sexes. Females attain sexual maturity in larger sizes than males. The reproductive cycle of females presented a seasonal pattern, with advanced vitellogenesis occurring from middle winter to middle spring and oviductal eggs occurring from middle winter to middle summer. The real fecundity ranged from two to eigth eggs and the expected fecundity varied from one to 12 secondary follicles. No significant correlation was found between females body size and the following parameters: real fecundity, length of the largest egg and potential fecundity. Therefore, E. j. coralliventris presents a seasonal reproductive pattern, which seems to follow the rainfall profile observed for the studied region. This may represent a strategy of energy gain associated to the reproductive cycle, considering that the food resources most explored by this species are anurans that present higher activity during rainy periods.

Abstract: Herein we investigated diet, sexual dimorphism and reproductive biology of two sympatric congeneric species at the coastal Brazilian Pampa, Philodryas aestiva and P. patagoniensis. Analysis of the stomach content of the scansorial Philodryas aestiva revealed that it feeds mainly on Anura and small mammals, while it occasionally consumes Insecta, Squamata and Aves. The more terrestrial Philodryas patagoniensis presented a broader diet, composed mainly of Anura, Squamata and small mammals. Insecta and Actinopterygii were found in lower frequencies. In females of both species, snout-vent length was significantly larger than in males, while tail length/snout-vent length ratio was significantly higher in males. Males reach sexual maturity at smaller sizes than females in both species. Fecundity was higher in P. patagoniensis (3 to 24 eggs; 15 ± 8.15) than in P. aestiva (10 to 20 eggs; X = 14.50 ± 3.53). Females of P. aestiva showed secondary follicles in all seasons while eggs occurred from middle-winter to early-summer. Secondary follicles occurred throughout the year in P. patagoniensis, but concentrated in spring. Eggs occurred in late-summer, middle-autumn and spring. Both species presented positive correlations between SVL and clutch size. Differences in analyzed traits seem to reflect divergences in species morphology and use of habitat/microhabitat.

ABSTRACT We investigated reproductive features of the dipsadid snake Erythrolamprus poecilogyrus sublineatus in the southernmost Brazilian coast, a subtropical region characterized by well-marked seasons. Females are significantly smaller than males, have a shorter tail, and reach sexual maturity at later times along their development. In contrast to tropical subspecies, E. p. sublineatus females presented a seasonal pattern, with secondary follicles occurring from late winter to early autumn and egg production restricted to the whole spring and early summer. Males presented seasonal variation in testes volume (increase in autumn and decrease in winter) while no significant seasonal variation was found in ductus deferens width. The number of oviductal eggs varied from two to nine, thus, real fecundity is also inferior than that observed in tropical E. poecilogyrus forms. Considering the thermal requirements for reproduction, it is possible that the colder climatic conditions of the southern Brazilian coast have shaped the seasonal reproductive pattern in E. p. sublineatus. The shorter body size of this subspecies may also represent a conditioning factor of low fecundity.

RESUMO As serpentes Erythrolamprus jaegeri jaegeri e Erythrolamprus poecilogyrus sublineatus são simpátricas e sintópicas na região costeira do extremo sul do Brasil. Aqui analisamos a composição da dieta para avaliar a amplitude de nicho e a seleção de presas por ambas as espécies. Foram examinados 192 espécimes, e a análise dos conteúdos estomacais revelou que ambas as espécies predominantemente consomem anuros. No entanto, a dieta de E. j. jaegeri consiste principalmente de peixes e anfíbios, enquanto a de E. p. sublineatus é mais ampla, incluindo peixes, anfíbios, répteis e mamíferos. O Índice Padronizado Levins apresentou valores mais baixos para E. j. jaegeri (BA = 0,17) do que para para E. p. sublineatus (BA = 0,61), evidenciando estratégias especialistas e generalistas para cada espécie, respectivamente. Em relação à seleção das presas, E. p. sublineatus apresentou maior comprimento rostro-cloacal e maior cabeça, boca e mandíbula do que E. j. jaegeri e se alimenta de presas maiores. Além disso, foram confirmadas correlações positivas entre tamanho e peso de predadores e presas, em ambas as espécies. Os resultados mostram o desenvolvimento de diferentes mecanismos para a coocorrência das duas espécies, tais como seleção de presa por tamanho, de tal modo que o tamanho do predador esteja relacionado ao tamanho de sua presa; ou pelo desenvolvimento de estratégias diferentes para diminuir a sobreposição de nichos entre as espécies.

ABSTRACT The snakes Erythrolamprus jaegeri jaegeri and Erythrolamprus poecilogyrus sublineatus are sympatric and syntopic in the coastal region of southern Brazil. Herein, we analyzed the diet composition to evaluate the niche breadth and the prey selection by both species. We examined 192 specimens, and analysis of stomach contents revealed that both species predominantly consume anurans. However, the diet of E. j. jaegeri consists mainly of fish and amphibians, whereas that of E. p. sublineatus is broader, including fish, amphibians, reptiles and mammals. The Standardized Levins Index presented lower values for E. j. jaegeri (BA = 0.17) than for E. p. sublineatus (BA = 0.61), evidencing specialist and generalist strategies for each species, respectively. Regarding prey selection, E. p. sublineatus presented a larger snout-vent length, head, mouth and lower jaw than E. j. jaegeri and fed on larger prey. In addition, positive correlations between the size and weight of predators and prey were confirmed in both species. The results show the development of different mechanisms for co-occurrence of the two species, such as prey selection by size, such that the size of the predator is related to the size of their prey, or by developing different strategies to decrease niche overlap between species.

RESUMO A variação geográfica no tamanho e forma do crânio do rato-do-pântano Scapteromys tumidus foi examinada em amostras de oito clusters geográficos, abrangendo a maior parte da distribuição no sul do Brasil e no Uruguai, usamos dois métodos de geometria morfométrica bidimensional para as vistas dorsal, ventral e lateral do crânio. Os descritores geométricos não mostraram diferenças significativas no tamanho do crânio entre os clusters geográficos, enquanto que as diferenças na forma foram altamente significativas. Encontramos correlação significativa e moderada entre distâncias geográficas e morfológicas, corroborando o modelo de isolamento-por-distância. Amostras da planície costeira central do Rio Grande do Sul foram as mais diferenciadas, segregando completamente de todas as outras amostras na análise de variáveis canônicas para a vista dorsal. As regiões visivelmente mais variáveis no crânio foram o arco zigomático (principalmente a raiz esquamosal do zigomático) e as bordas laterais da caixa craniana. Uma vez que a correlação entre as distâncias geográfica e morfológica não foi alta, é possível que outros fatores (heterogeneidade ambiental e/ou barreiras geográficas) venham atuando na diferenciação do crânio de S. tumidus.

ABSTRACT The geographic variation in skull size and shape of the swamp rat Scapteromys tumidus was examined in samples from eight geographic clusters in almost of its distribution in southern Brazil and Uruguay. For analysis we used two-dimensional geometric morphometric methods for dorsal, ventral and lateral views of the skull. The geometric descriptors showed no significant differences in skull size between geographic clusters, while differences in shape were highly significant. We found a significant and moderate correlation between geographic and morphological distances, corroborating the isolation-by-distance model. Samples from the Rio Grande do Sul central coastal plain were the most differentiated, segregating completely from all other samples in canonical variate analysis for the dorsal view. The most visible variable regions in skull were the zygomatic arch (mainly the squamosal root of zygomatic) and the lateral braincase borders. Once correlation between geographic and morphological distances were not strong, it is possible that other factors (environmental heterogeneity and/or geographic barriers) may are acting in S. tumidus skull differentiation.

Apesar de sua ampla distribuição e abundância em determinados habitats, o mão-pelada Procyon cancrivorus (G. Cuvier, 1798) é considerado uma das menos conhecidas espécies de carnívoro Neotropical. No presente estudo analisamos a dieta de P. cancrivorus em uma mata paludosa e uma ilha estuarina no extremo sul do Brasil. Frutos da palmeira gerivá Syagrus romanzoffiana foi o item mais consumido na mata paludosa, seguido por insetos e moluscos. Pequenos mamíferos, seguidos por frutos de Bromelia antiacantha (Bromeliaceae) e crustáceos braquiúros foram os itens mais frequentes na ilha estuarina. Outros itens encontrados em menor frequência foram frutos de Solanum sp., Psidium sp., Smilax sp. and Dyospiros sp., diplópodos, escorpiões, peixes, anfíbios anuros, répteis (teiú e serpentes), aves e mamíferos de médio porte (gambá-da-orelha-branca, tatu e ratão-do-banhado). Os valores do índice de Levin (mata paludosa: 0.38; ilha estuarina: 0.45) indicam uma aproximação a uma posição mediana entre uma dieta especialista e bem distribuída. O índice de Pianka (0.80) mostrou uma considerável similaridade na dieta entre os dois sistemas. Procyon cancrivorus apresentou uma dieta variada nas áreas estudadas e pode desempenhar um importante papel como dispersor de sementes em ecossistemas costeiros no extremo sul do Brasil.

Despite its wide range and abundance on certain habitats, the crab-eating raccoon Procyon cancrivorus (G. Cuvier, 1798) is considered one of the less known Neotropical carnivore species. In the present study we analyzed the diet of P. cancrivorus in a peat forest and in an estuarine island in southernmost Brazil. Fruits of the gerivá palm tree Syagrus romanzoffiana were the most consumed item in the peat forest, followed by insects and mollusks. Small mammals, followed by Bromelia antiacantha (Bromeliaceae) fruits and brachyuran crustaceans were the most frequent items in the estuarine island. Other items found in lower frequencies were Solanum sp., Psidium sp., Smilax sp. and Dyospiros sp. fruits, diplopods, scorpions, fishes, anuran amphibians, reptiles (black tegu lizard and snakes), birds and medium-sized mammals (white-eared opossum, armadillo and coypu). Levin’s index values (peat forest: 0.38; estuarine island: 0.45) indicate an approximation to a median position between a specialist and a well distributed diet. Pianka’s index (0.80) showed a considerable diet similarity between the two systems. Procyon cancrivorus presented a varied diet in the studied areas and may play an important role as seed disperser on coastal environments in southernmost Brazil.

Este trabalho apresenta dados sobre os aspectos sobre cariótipo, distribuição geográfica, habitats de ocorrência e morfometria de Cryptonanus guahybae (Tate, 1931), baseados em 15 espécimes tombados no Museu de Ciências Naturais da Universidade Luterana do Brasil. Os exemplares são procedentes das seguintes localidades do estado do Rio Grande do Sul: 1.- Usina Hidrelétrica de Itá; 2. Derrubadas; 3. Estação Ecológica de Aracuri - Esmeralda (Planalto Meridional); 4. Tapes (Planície Costeira Interna); 5. Venâncio Aires (Depressão Central); e 6. Área de Proteção Ambiental da Lagoa Verde e entorno - Rio Grande (Planície Costeira Externa). Ampliamos a distribuição geográfica da espécie cerca de 250 km em direção norte e 100 km em direção sul, sendo os municípios de Derrubadas e Rio Grande, respectivamente, os novos limites norte e sul dessa distribuição. O registro no município de Derrubadas também expande cerca de 180 km em direção oeste o limite de distribuição geográfica de C. guahybae. A análise citogenética dos espécimes do Rio Grande revelou um número diplóide (2n) igual a 14 e de braços autossômicos (NF) igual a 24, sendo os pares 1, 2 e 3 submetacêntricos, o par 4 metacêntrico, os pares 5 e 6 subtelocêntricos, o cromossomo sexual X submetacêntrico e o Y acrocêntrico. O par 6 apresentou regiões organizadoras de nucléolo (Ag-RON) nos telômeros de seus braços curtos. Dados sobre os exemplares procedentes do município de Rio Grande indicam a ocorrência da espécie em matas de restinga, nos biótopos de interior e bordas de mata arenosa ciliar e interior, e clareiras de mata palustre, sendo efetuadas capturas no solo e no sub-bosque (altura = 0.5 - 1.55 m).

This article reports data on karyotype, geographic distribution, habitat occurrence and morphometry of Cryptonanus guahybae (Tate, 1931) based on 15 specimens deposited in the mammal collection of the Museu de Ciências Naturais of Universidade Luterana do Brasil. The specimens were recorded in the following localities in Rio Grande do Sul state: 1. Itá Hydroelectric Power Plant; 2. Derrubadas; 3. Aracuri Ecological Station - Esmeralda (Southern Plateau); 4. Tapes (Inner Coastal Plain); 5. Venâncio Aires (Central Depression) and 6. Lagoa Verde Reserve Area and surroundings - Rio Grande (External Coastal Plain). We amplified the extension of the species distribution ca. 100 km southwards and 250 km northwards, being the municipalities of Derrubadas and Rio Grande, respectively, the new northern and southern limits of its geographical range. Derrubadas municipality record also extends C. guahybae distribution ca. 180 km westwards. Cytogenetic analysis showed a diploid number of 2n=14 and fundamental number FN=24 with pairs 1, 2 and 3 being submetacentrics, pair 4 metacentric, pairs 5 and 6 subtelocentrics, while sexual chromosomes X and Y were a submetacentric and an acrocentric, respectively. Ag-NOR analysis showed a single region located in the short arms of pair 6. In relation to habitat occurrence, the specimens from Rio Grande municipality were recorded in restinga forest, occupying the inner or borderline of sandy riparian forest and inner and gaps of flooded forest. Individuals were trapped on the ground and in short trees (heights = 0.5 - 1.55 m).