Identification of microchips through diagnostic imaging helps to determine the longevity of the golden lancehead (Bothrops insularis) in captivity

As serpentes vindas da natureza e encaminhadas para centros de reabilitação ou de pesquisa têm uma idade incerta. Na natureza, esses animais, muitas vezes atingem um tamanho corpóreo menor do que os indivíduos cativos devido a uma menor frequência de alimentação. Assim, a idade de uma cobra recém-chegada da natureza é geralmente estimada com base em seu tamanho corpóreo, o qual é comparado com dados em cativeiro. A utilização dos meios de diagnóstico por imagem tem auxiliado a medicina na análise das serpentes em cativeiro, mediante avaliação da estrutura óssea, dos órgãos e de alterações. Este trabalho relata o uso de diagnóstico por imagem (radiografia e ultrassonografia) para identificar a presença de microchips e, consequentemente, estimar a idade de uma Bothrops insularis em cativeiro.

Reproductive cycle and sperm storage of female coral snakes, Micrurus corallinus and Micrurus frontalis

We analyzed the hypothesis that the lack of synchronization between the mating and ovulation period of Micrurus frontalis (BRT clade) is indicative of the capacity of females to store sperm. Conversely, since these reproductive events occur in the same season for Micrurus corallinus (BRM clade), sperm storage is not expected. Thus, we analyzed the reproductive cycle of female M. corallinus and M. frontalis, and investigated the occurrence of sperm storage. Our results showed that these two species of coral snakes (clades BRM and BRT) possess different reproductive cycles. Micrurus frontalis exhibits an extensive reproductive period encompassing three seasons (summer, autumn and winter), while M. corallinus directs secondary vitellogenesis and ovulation to the hottest period of the year (spring and summer). We confirm, for the first time, the strategy of sperm storage (SSr) in females of the genus Micrurus. We observed sperm storage receptacles located in the non-glandular uterus in all seasons of the year for M. corallinus and in spring, summer and autumn in M. frontalis. Furthermore, the presence of SSr in females in the non-reproductive (post-ovulatory) period, the verification of myoid cells around the receptacles and secretion of neutral carbohydrates in the lumina of SSrs may indicates a long-term storage. The posterior infundibulum is another possible region of sperm storage by the presence of tubular ciliated gland; however, reproductive studies with other species of the genus are necessary for a better understanding of the reproductive strategies of the BRT and BRM clades.

Anatomy of the reproductive system of a population of Amerotyphlops brongersmianus from southeastern Brazil (Serpentes: Scolecophidia)

Amerotyphlops brongersmianus (Vanzolini, 1976) is distributed in Brazil from the Atlantic Rainforest to the Cerrado biome. Only few studies have focused on the gross anatomy, reproductive organs, and histological data of typhlopids. We accessed information from the anatomy of gonads of 95 individuals collected at different months in the Restinga de Jurubatiba National Park, Rio de Janeiro state, Brazil. This included histological sections of the testes, ductus deferens and sexual segment of kidney in males, and oviducts in females, from which fecundity was determined. Results revealed a correlation between gross morphology and histology of the reproductive system. Testes volume increased during spermatogenesis, and the ductus deferens diameter increased with the presence of spermatozoa. Additionally, changes occurred in kidney morphology, which showed a smooth or rough surface, the latter corresponding to the development of the sexual segment of the kidney (SSK). Spermatozoa were found inside the lumen of the SSK of some males. Females lacked left oviducts and showed changes in morphological and histological aspects of the right oviducts throughout the year. In summer and spring the uterus showed undeveloped structures, while during winter this organ showed conspicuously developed glands and appeared pleated and opaque upon gross examination. The infundibulum was pleated in most females throughout the year and one female had spermatozoon in a receptacle located in the posterior infundibulum. In spring this organ was enlarged compared to winter, with a thinner epithelium. Fecundity corresponded to 7–11 eggs.

Infundibular sperm storage and uterine muscular twisting in the Amazonian lancehead, bothrops atrox

Although knowledge about the reproduction of snakes of the genus Bothrops has increased recently, many questions remain regarding sperm storage by these neotropical pitvipers. The relationship between two known sperm storage sites—the nonglandular uterus and the infundibulum—has yet to be detailed for Bothrops. In addition, the formation of uterine muscular twisting (UMT) and its function in sperm storage in the nonglandular uterus have been questioned. This article presents data on both sperm storage sites (posterior infundibulum and nonglandular uterus) in the Amazonian lancehead, Bothrops atrox, aiming to address the role of UMT in bothropoid reproduction considering female reproductive stages, timing of sperm storage, and morphology and histochemistry of sperm receptacles. The oviduct of B. atrox is composed of the infundibulum (anterior and posterior), the glandular uterus, the nonglandular uterus and the pouch. Sperm storage occurs in the posterior infundibulum and nonglandular uterus in vitellogenic females. In the posterior infundibulum sperm is stored in receptacles, while in the nonglandular uterus it is stored in crypts in the UMT of vitellogenic females. Both sperm storage sites possess granules testing positive for neutral mucopolysaccharides in the presence of spermatozoa, possibly favoring the conditions for spermatozoa surveillance during sperm storage in the reproductive tract.

Atividade reprodutiva de Bothrops insularis (Amaral, 1921) na Ilha de Queimada Grande - SP

Estudos sobre comunidades insulares são exíguos, embora a Teoria de Equilíbrio de Biogeografia de Ilhas tem sido utilizada para interpretar a organização das mesmas. Bothrops insularis é uma serpente criticamente ameaçada de extinção e endêmica da Ilha da Queimada Grande (IQG) - SP. Descrita em 1921 por Afrânio do Amaral, esta espécie alcança um metro de comprimento, tem coloração pardo-amarelada, apresenta atividade diurna e possui hábito semi-arborícola, condicionado por sua alimentação à base de aves migratórias. Em 1959 um estudo populacional na ilha verificou a proporção de machos, fêmeas e intersexos. O estudo envolveu duas amostras no intervalo de aproximadamente 25 anos. Os resultados mostraram uma mudança na proporção dos sexos durante esse período, com uma redução do número de machos, aumento do número de indivíduos intersexos e frequência estacionária das fêmeas "verdadeiras". Recentemente estudos têm demonstrado apenas a existência de fêmeas intersexos e machos. No presente estudo analisou-se a frequência e o número de machos, fêmeas e intersexos de Bothrops insularis, associando hábitos reprodutivos e comportamentais in situ. Foram realizadas expedições a Ilha da Queimada Grande entre 2014 a 2015. As observações dos indivíduos visualmente detectados foram feitas ao longo da trilha por meio de procura visual limitada por tempo em transectos, abrangendo alguns microhabitats mais acessíveis. Nesse método é possível coletar informações mais precisas sobre a atividade do animal e sua localização no hábitat. Dados de coleta entre 1995 a 1997 referentes a expedições realizadas à IQG por terceiros foram compilados e utilizados para comparação com a atividade reprodutiva entre 2014 e 2015.

Avaliação seminal na falsa coral Oxyrhopus guibei

A subordem das serpentes é composta por uma variedade de espécies que podem apresentar aspectos reprodutivos distintos entre si, ocorrendo variações correlacionadas ao ambiente em que vivem e a estação do ano. Para conhecer o real status reprodutivo de um animal deve ser levado em conta o estudo morfológico macro e microscópico aliado a técnicas como a histologia para analisar estruturas ínfimas e suas funções. A falsa coral (Oxyrhopus guibei) é um animal sinantrópico e não peçonhento comum na região metropolitana de São Paulo e possui um ciclo reprodutivo contínuo. Esse projeto descreveu o ciclo espermático nos machos de Oxyrhopus guibei ao longo do ano, evidenciando picos de produção espermática entre o inverno e a primavera. A coleta de sêmen ocorreu mensalmente nos animais mantidos no biotério do Laboratório de Ecologia e Evolução (LEEV) do Instituto Butantan.

Reproductive biology of Bothrops atrox (Serpentes, Viperidae, Crotalinae) from the brazilian Amazon

Reproductive seasonality is common among snakes, with mating, pregnancy, and birth or oviposition occurring only during few months of the year and modulated mainly by two environmental phenomena—temperature and rainfall. Species of Bothrops inhabit regions with varied climatic conditions, including those that are tropical, subtropical, equatorial, and semiarid. Bothrops atrox is an endemic and widespread species of the Amazon rain forest. Such habitat is characterized by an equatorial climate with little variability in temperature and humidity, but marked seasonality in intense precipitation. We investigated several aspects of the reproductive biology of B. atrox, including the reproductive cycle, the sexual segment of the kidney (SSK), sperm storage, and the possible influence of temperature and rainfall on pregnancy duration, birth, and spermatogenesis. Specifically, we examined museum specimens to describe sexual dimorphism, litter size, and male and female urogenital cycles through macroscopic and histological analyses. Females of B. atrox exhibited follicular recrudescence mainly from January to April (part of the wet season). Pregnant females were found throughout the year (except May), but births were found to occur mainly at the end of the dry season (August–October). Males exhibited SSK hypertrophy and sperm production in the wet season (November–April). Females were found to be larger than males, but males of B. atrox—as with other members of the B. atrox species complex—obtain relatively larger body sizes when compared with other species of Bothrops, which might be an adaptive response to male–male combat in this species. Together, our results show that B. atrox from Amazonia has a unique reproductive strategy (for each sex) among pit vipers, indicating greater reproductive plasticity when compared with its congeners.

Morphological variation and sexual dimorphism in two sympatric dipsadine snakes from Southern Brazil

Snakes have high morphological variation, including between sexes. Most of these variations are evidenced only by linear measurements, which are generally restricted to size traits. Using traditional and geometric morphometrics methods we analyze how body size attributes and head size and shape varies between sexes and species of two sympatric Tachymenini snakes, Thamnodynastes strigatus and Tomodon dorsatum. We took body size measurements from 87 specimens of T. strigatus and 83 specimens of T. dorsatum. We also extracted head shape and size of 146 specimens of T. strigatus and 156 specimens of T. dorsatum. Our results showed sexual differences in some body size attributes and in head shape and size. Females of both species had larger SVL, BM, HW, BW and heads than in males. But, T. strigatus is not sexually dimorphic in head size. Females of the T. strigatus also exhibited an enlargement of the parietal region compared to the males, while T. dorsatum females exhibited a wider snout than males. These sexual differences could be a result of fecundity selection and may also indicate that females consume larger preys than conspecific males. At the species level, T. strigatus is larger in body and head size than T. dorsatum. The head shape of T. strigatus is characterized by a more elongated head with larger frontal and prefrontal scales and slender snout compared to T. dorsatum. Shape differences between these two snakes probably evolved in association with divergences in habitat use (e.g. terrestrial and arboreal) and diet specialization (e.g. piscivory, and malacophagy).

A histological and ultrastructural investigation of the female reproductive system of the water snake (Erythrolamprus miliaris): oviductal cycle and sperm storage

We studied the structural and cellular organisation of the oviduct of Erythrolamprus miliaris including its morphological variation during the reproductive cycle using light microscopy, scanning electron microscopy and transmission electron microscopy. Four anatomically distinct regions compose the oviduct of E. miliaris including the anterior and posterior infundibulum, glandular uterus, non-glandular uterus and pouch. The cells of the oviductal epithelium secrete material by apocrine and merocrine processes, which vary between the anatomical regions and according to each phase of the reproductive cycle. The infundibular epithelium secretes electron dense vacuoles, which suggests the production of lipids, whereas the epithelial secretion of the glandular uterus, non-glandular uterus and pouch creates lucent and slightly electron dense vacuoles, indicating the production of glycoproteins. The timing of mating, vitellogenesis and sperm storage directly influences the morphofunctional alterations in the oviducts of E. miliaris. Sperm storage occurs only in the infundibular receptacles with increased production of the neutral carbohydrates in the presence of male gametes. Sperm storage happens in vitellogenic, non-vitellogenic and pregnant females of E. miliaris. Thus, females may be able to produce multiple clutches at different seasons of the year regardless of mating during autumn.

Uterine and eggshell modifications associated with the evolution of viviparity in South American water snakes (Helicops spp.)

The evolution of viviparity requires eggshell thinning to bring together the maternal uterus and extraembryonic membranes to form placentae for physiological exchanges. Eggshell thinning likely involves reduced activity of the uterine glands that secrete it. We tested these hypotheses by comparing the uterine and eggshell structure and histochemistry among oviparous and viviparous water snakes (Helicops) using phylogenetic methods. Eggshell thinning occurred convergently in all three origins of viviparity in Helicops and was accomplished by the loss of the mineral layer and thinning of the shell membrane. Uterine glands secrete the shell membrane in both oviparous and viviparous Helicops. These glands increase during vitellogenesis regardless of the reproductive mode, but they always reach smaller sizes in viviparous forms. As there is no phylogenetic signal in eggshell thickness and gland dimensions, we conclude that interspecific differences are related to reproductive mode and not phylogeny. Therefore, our results support the hypothesis that eggshell thinning is associated with the evolution of viviparity and that such thinning result from a reduction in gland size in viviparous taxa. Interestingly, the shell membrane thickness of viviparous females of the reproductively bimodal Helicops angulatus is intermediate between their oviparous and viviparous congeners. Thus, although eggshell thinning is required by the evolution of viviparity, a nearly complete loss of this structure is not. However, uterine gland dimensions are similar across viviparous Helicops. Fewer glands or their functional repurposing may explain the thinner shell membrane in viviparous species of Helicops in comparison to viviparous females of the bimodal H. angulatus.

How does oocyte uptake occur? A macroscopic study of the ovarian and oviductal modifications for egg capture in the coral-snake Micrurus corallinus

The processes of follicular development, ovulation, egg capture, and egg transport vary among vertebrates. Therefore, analysis of the reproductive tract of several lineages is needed for understanding the evolutionary changes of the reproductive system. In turtles, the ovulated eggs are released into the coelomic cavity and taken up by one of the two oviducts, a phenomenon called extrauterine migration of eggs. However, the process of egg uptake in lizards is different. The egg is ovulated directly into the infundibulum, and oocyte uptake by the contralateral oviduct rarely occurs. The same pattern has been hypothesized to occur in snakes. To test this hypothesis, we analyzed the reproductive tract of female Micrurus corallinus preserved in zoological collections. We examined the anatomical characteristics of the infundibulum and ovary and compared the reproductive output between the ovaries to verify the mechanism of egg capture and the anatomical viability of extrauterine migration of eggs. The reproductive output of the right ovary was higher than that of the left ovary, and the higher number of eggs in the right oviduct is due exclusively to the production of the ipsilateral ovary. Several anatomical features prevent extrauterine migration of eggs, including the asymmetry of the reproductive system, the arrangement of the ovarian follicles in a single row, and the formation of a wrapping around the ovary and infundibulum by the visceral pleuroperitoneum membrane (preventing against ectopic eggs). Therefore, the hypothesis of egg capture by the contralateral oviduct is anatomically infeasible in M. corallinus and possibly in other snakes.

Deworming protocols of island snakes kept in capitivity at the Butantan Institute

Bothrops insularis and B. alcatraz are critically endangered species inhabiting two different coastal islands of the state of São Paulo. Although they are closely related species, they show distinct morphological characteristics due to their isolation from the continent. There is a general lack of studies on conservation and captive husbandry of these species, including their parasites. Our aim was to evaluate the deworming protocols used in B. insularis and B. alcatraz in captivity. We evaluated three deworming protocols through fecal examination: (1) adult B. insularis were treated with ivermectin and praziquantel, (2) adult B. alcatraz were treated with ivermectin, and (3) juvenile B. insularis and B. alcatraz were treated with ivermectin. The snakes are kept in the Laboratory of Ecology and Evolution at the Instituto Butantan (São Paulo, Brazil) for conservation purposes. To evaluate the deworming protocols, we performed the Willis-Mollay (1921) technique. After treating with the first protocol, 19% of the animals showed only eggs of a pseudoparasite (Syphacia obvelata). After the second protocol, 75% of the animals showed cestodes (Ophiotaenia sp.). After the third protocol, 32% of the animals showed only the pseudoparasite, S. obvelata. The pseudoparasite was found only in B. insularis individuals that ate adult mice in captivity. However, cestode eggs were found only in those adult snakes of the second protocol that did not receive praziquantel. Based on the negative results for pathogenic parasites, we conclude that the first protocol was effective for adult snakes whereas the third protocol was effective for juveniles.

Bothrops insularis e B. alcatraz são espécies criticamente ameaçadas de extinção que habitam duas ilhas diferentes da costa do estado de São Paulo. Embora elas sejam espécies intimamente relacionadas, apresentam características morfológicas distintas devido ao seu isolamento do continente. Há uma falta geral de estudos sobre conservação e criação em cativeiro dessas espécies, incluindo seus parasitas. O objetivo desse trabalho foi avaliar os protocolos de vermifugação utilizados em B. insularis e B. alcatraz em cativeiro. Foram avaliados três protocolos de vermifugação através do exame coproparasitológico: (1) B. insularis adultas foram tratadas com ivermectina e praziquantel, (2) B. alcatraz adultas foram tratadas com ivermectina, e (3) B. insularis e B. alcatraz juvenis foram tratadas com ivermectina. As serpentes são mantidas no Laboratório de Ecologia e Evolução do Instituto Butantan (São Paulo, Brasil) para projetos de conservação. Para avaliar os protocolos de vermifugação, foi realizado a técnica de Willis-Mollay (1921). Depois de tratado com o primeiro protocolo, 19% dos animais apresentaram somente ovos de pseudoparasitas, (Syphacia obvelata). Depois do segundo protocolo, 75% dos animais apresentaram cestóides (Ophiotaenia sp.). Depois do terceiro protocolo, 32% dos animais apresentaram somente pseudoparasitas, S. obvelata. O pseudoparasita foi encontrado somente em indivíduos de B. insularis que comeram camundongos adultos em cativeiro. Contudo, ovos de cestóides foram encontrados somente nas serpentes adultas do segundo protocolo que não receberam praziquantel. Com base nos resultados negativos para parasitas patogênicos, concluímos que o primeiro protocolo foi eficaz para serpentes adultas, enquanto que o terceiro protocolo foi efetivo para juvenis.

Uterine and eggshell modifications associated with the evolution of viviparity in South American water snakes (Helicops spp.)

The evolution of viviparity requires eggshell thinning to bring together the maternal uterus and extraembryonic membranes to form placentae for physiological exchanges. Eggshell thinning likely involves reduced activity of the uterine glands that secrete it. We tested these hypotheses by comparing the uterine and eggshell structure and histochemistry among oviparous and viviparous water snakes (Helicops) using phylogenetic methods. Eggshell thinning occurred convergently in all three origins of viviparity in Helicops and was accomplished by the loss of the mineral layer and thinning of the shell membrane. Uterine glands secrete the shell membrane in both oviparous and viviparous Helicops. These glands increase during vitellogenesis regardless of the reproductive mode, but they always reach smaller sizes in viviparous forms. As there is no phylogenetic signal in eggshell thickness and gland dimensions, we conclude that interspecific differences are related to reproductive mode and not phylogeny. Therefore, our results support the hypothesis that eggshell thinning is associated with the evolution of viviparity and that such thinning result from a reduction in gland size in viviparous taxa. Interestingly, the shell membrane thickness of viviparous females of the reproductively bimodal Helicops angulatus is intermediate between their oviparous and viviparous congeners. Thus, although eggshell thinning is required by the evolution of viviparity, a nearly complete loss of this structure is not. However, uterine gland dimensions are similar across viviparous Helicops. Fewer glands or their functional repurposing may explain the thinner shell membrane in viviparous species of Helicops in comparison to viviparous females of the bimodal H. angulatus.

Reproductive biology of Philodryas patagoniensis (Snakes: Dipsadidae) in south Brazil: female reproductive cycle

In this study, we describe the female reproductive cycle of Philodryas patagoniensis in south Brazil, which was described through morpho-anatomical and histological analyses. The peak of secondary vitellogenesis occurred during winter-spring (July-December), ovulation in spring (October-December), mating and fertilization in spring-summer (October-February), oviposition in spring-autumn (October-May) and births from late spring to autumn (December-July). The diameter of vitellogenic follicles/eggs was larger in winter-spring than in other seasons. The diameter of the shell glands was also larger in winter-spring. In spite of the clear reproductive peak, gonads only showed reduced activity in the autumn. Therefore, at the individual level, females have a discontinuous cyclical reproduction; in the populational level, the reproductive cycle is seasonal semisynchronous. We support the hypothesis that P.patagoniensis have the ability to produce multiple clutches with long-term stored sperm. Sexual dimorphism in body size was evident, and females are significantly larger and heavier than males. Larger females were able to produce follicles and eggs in larger amount and size. The maternal body size was positively related to the reproductive effort and fecundity. To conclude, we deliberated about the proximal and distal causes that influence the reproductive traits and patterns of P.patagoniensis.

Hundred legs good, two fangs better: adult centipede (Scolopendridae) devoured by a juvenile Amazon lancehead, Bothrops atrox (Viperidae) / Uma centena de pernas é eficaz, mas duas presas são ainda melhores: lacraia adulta (Scolopendridae) devorada por uma jovem serpente amazônica, Bothrops atrox (Viperidae)

Centipedes are part of the diet of several snake species of the genus Bothrops. However, reports on predation of centipedes by snakes are normally incomplete, and important data for natural history studies as the species identification and size of the prey are rarely published. The aim of this work was to report the presence of the centipede Scolopendra viridicornis in the digestive tract of the Amazon pit viper B. atrox. The snake specimen is an immature female from Aripuanã, state of Mato Grosso, Brazil, having a 623 mm snout-vent length. The centipede is an adult Scolopendra viridicornis, estimated to be 190 mm long, and found in the snake's stomach. The success in preying on this large and potentially dangerous centipede could be explained by the snake's dimensions, large enough for overpowering the prey, but still retaining characteristics of youth, such as venom with specific action against specific prey items.

Lacraias fazem parte da dieta de diversas espécies de serpentes do gênero Bothrops. Entretanto, informações importantes para estudos de história natural, como identificação da espécie e tamanho de presas, são raramente publicados. O objetivo desse trabalho é registrar a presença de uma lacraia Scolopendra viridicornis, no trato digestivo de uma jararaca da Amazônia, Bothrops atrox. A serpente estudada é uma fêmea imatura, com 623 mm de comprimento rostro-cloacal, proveniente de Aripuanã, estado de Mato Grosso, Brasil. A lacraia é um adulto de Scolopendra viridicornis parcialmente digerida, com aproximadamente 190 mm de comprimento. O sucesso na predação dessa grande e perigosa presa pode ser explicado pelas dimensões da serpente, que é grande o suficiente para dominar a presa, mas ainda retém características juvenis, como veneno com ação específica em determinados ítens alimentares.

Mating plugs and male sperm storage in Bothrops cotiara (Serpentes, Viperidae)

We describe two new aspects of male reproduction in the pit viper Bothrops cotiara: the formation of mating plugs and epididymal sperm storage. Based on histological analyses of specimens (four males and three females), we propose that long-term sperm storage occurs in the ductus deferens, whereas macroscopic hypertrophy indicates that the epididymis may be a short-term sperm storage site. Secretions of the sexual segment of the kidneys probably form the mating plug that males deposit in the female vagina during copulation. A mating plug without sperm was observed in the spring. Future studies should address the functions and longevity of mating plugs and the role of the epididymis in Bothrops reproduction.

Hundred legs good, two fangs better: adult centipede (Scolopendridae) devoured by a juvenile Amazon lancehead, Bothrops atrox (Viperidae) / Uma centena de pernas é eficaz, mas duas presas são ainda melhores

Centipedes are part of the diet of several snake species of the genus Bothrops. However, reports on predation of centipedes by snakes are normally incomplete, and important data for natural history studies as the species identification and size of the prey are rarely published. The aim of this work was to report the presence of the centipede Scolopendra viridicornis in the digestive tract of the Amazon pit viper B. atrox. The snake specimen is an immature female from Aripuana, state of Mato Grosso, Brazil, having a 623 mm snout-vent length. The centipede is an adult Scolopendra viridicornis, estimated to be 190 mm long, and found in the snake's stomach. The success in preying on this large and potentially dangerous centipede could be explained by the snake's dimensions, large enough for overpowering the prey, but still retaining characteristics of youth, such as venom with specific action against specific prey items.

Lacraias fazem parte da dieta de diversas espécies de serpentes do gênero Bothrops. Entretanto, informações importantes para estudos de história natural, como identificação da espécie e tamanho de presas, são raramente publicados. O objetivo desse trabalho é registrar a presença de uma lacraia Scolopendra viridicornis, no trato digestivo de uma jararaca da Amazônia, Bothrops atrox. A serpente estudada é uma fêmea imatura, com 623 mm de comprimento rostro-cloacal, proveniente de Aripuanã, estado de Mato Grosso, Brasil. A lacraia é um adulto de Scolopendra viridicornis parcialmente digerida, com aproximadamente 190 mm de comprimento. O sucesso na predação dessa grande e perigosa presa pode ser explicado pelas dimensões da serpente, que é grande o suficiente para dominar a presa, mas ainda retém características juvenis, como veneno com ação específica em determinados ítens alimentares.

Reproductive biology of the brazilian lancehead, bothrops moojeni (Serpentes, Viperidae), from the state of Sao Paulo, Southeastern Brazil

Bothrops moojeni inhabits riparian forests and adjacent open, wet areas in the Brazilian Cerrado. We address several aspects of the reproductive biology of a population from southeastern Brazil, including sexual maturation and dimorphism, male and female reproductive cycles, and sperm storage. We also provide the first record of male-male combat behavior in the wild. We sampled specimens held in the scientific collection of the Butantan Institute, Sao Paulo, Brazil. After macroscopic analyses and dissections, we collected the testes of males and the posterior uterus of females showing uterine muscular twisting for microscopic analyses. Males < 54.5 cm and females < 58.0 cm were sexually immature. Mature females are larger than males, although male-male combat is reported for this species. Male-male fighting and copulation occur during late summer in the wild. Histological analysis of the testes confirmed that sperm production occurs simultaneously with those reproductive events. Females showed an extended period of vitellogenesis, from February to November (late summer to spring). We observed stored sperm in the female reproductive tract during autumn. Because mating is not synchronous with ovulation, sperm storage is an obligatory component of the reproductive cycle of B. moojeni. Ovulation begins in August (winter) but most females with the presence of embryos in the oviducts occurred from January to March (summer). Parturition in captivity occurred in February, confirming that births are concentrated in the summer. Given that the Cerrado is highly fragmented in southeastern Brazil, studies on the reproductive biology of additional B. moojeni populations might provide useful information regarding intraspecific variation in reproduction in pit vipers.