Morphological variation and new distributional records of Rhadinella dysmica (Serpentes: Dipsadidae), with comparisons with other dark-colored congeners

Small, secretive snakes comprise an important part of the herpetofauna of the Neotropics and yet most species are known from a handful of specimens due to their habits and relatively inaccessible localities. The Mexican endemic Rhadinella dysmica is the westernmost species of the genus and was described based on a single adult female. Herein we provide information on new specimens, including their morphological variation and hemipenial structure, expand the known geographic range for the species, and comment on the morphological similarities of the “dark-colored” species of the genus.

Comparative vulnerability of Indosylvirana temporalis and Clinotarsus curtipes (Anura: Ranidae) tadpoles to water scorpions: importance of refugia and swimming speed in predator avoidance

The comparative vulnerability of two co-existing tadpole species (Indosylvirana temporalis and Clinotarsus curtipes) to their common predator, water scorpions (Laccotrephes sp.; Hemiptera: Nepidae), and the importance of refugia in predator avoidance were studied in the laboratory. In a total of 60 experimental trials, 10 tadpoles each of I. temporalis and C. curtipes of comparable body sizes were exposed to water scorpions (starved for 48 h). Thirty trials included refugia while 30 did not. The results of this study showed that in both the absence and the presence of refugia C. curtipes tadpoles fell prey to water scorpions more frequently than I. temporalis tadpoles. A main difference between the two species is the speed of swimming; Vmax of C. curtipes (24.73 cm/s) tadpoles is lower than that of I. temporalis (30.78 cm/s) tadpoles. This is likely to be the reason why more C. curtipes tadpoles were preyed upon than were I. temporalis tadpoles. Predation risk of tadpoles of both species was affected significantly by the presence of refuge sites. The vulnerability of both tadpole species was lower where refuge sites were available. The present study clearly shows that I. temporalis tadpoles avoid predation by water scorpions more effectively than do C. curtipes tadpoles.

High prevalence of anomalies in Nyctimantis brunoi (Anura: Hylidae) from a restinga protected area in southeastern Brazil

In the present study we monitored a population of Nyctimantis brunoi, a species commonly found in restingas of southeastern Brazil. Field activities were carried out in the Parque Nacional da Restinga de Jurubatiba (PNRJ), a protected area located in the northern portion of the state of Rio de Janeiro. Specimens were sampled through a complete species inventory. We analyzed 218 individuals, 32 (14.7%) of which have anomalies. Additionally, a subsample of 15 specimens were radiographed to verify the occurrence of skeletal anomalies not externally detectable and to verify if the classification of anomalies attributed by means of external examination are detectable in the osteological structure of the specimen. There are 12 types of anomalies recognized in this population, three of them only detectable through internal investigation (radiography). We verified that most of anomalies externally detectable were correctly classified when compared to the osteological morphology of the radiographed specimens. Thus, in this investigation, the study of external malformations was capable to detect 60% of the types of anomalies. We conclude that further ecotoxicological and epidemiological studies of the population of N. brunoi in the PNRJ are necessary to establish the origins of anomalies in this species.