Current Herpetology

The speciose genus Limnonectes exhibits a broad range of reproductive behavior and sizes at maturity. Two Southeast Asian species are near the low end of the size range and near one extreme of reproductive habits (their larvae are said to have direct development). Limnonectes hascheanus and L. limborgi are small, having a maximum snout-vent length of less than 40 mm, with reduced webbing and females with enlarged, pigment-less ova. The distinctions between these species have not been clear and L. limborgi has been treated as a junior synonym of L. hascheanus. We show that these two nominal species differ in size, development of odontoids in adult males, in extent of webbing, and mitochondrial and nuclear DNA sequence data. Their geographic ranges scarcely overlap, with L. hascheanus apparently being restricted to the southern part of the Malay Peninsula and L. limborgi being distributed in a large arc from southern Myanmar northward to northern Thailand and Laos before curving around to central Laos, northeastern Thailand, Cambodia, and southern Vietnam. Because the holotype of L. limborgi appears to have been lost, we describe a neotype, using a specimen from southern Myanmar studied by Boulenger.

We investigated a sample of apparently unique frogs from Sado Island, Japan. While being tentatively identified to Rana rugosa on the basis of general morphological resemblance, this form (yellow type) differs from the typical Japanese R. rugosa by showing deep yellow or orange coloration in abdomen and the ventral surfaces of legs, and by having much smoother skin on the entire body. For the Japanese populations of Rana rugosa, following four genetic forms are currently recognized: Kanto form (around Tokyo and northeastern Japan), Western Japan form (western Japan), XY form (central Japan), and ZW form (northwestern Japan). Of these, the latter two forms bear differentiated sex chromosomes of XX/XY and ZZ/ZW types, respectively, and are assumed to have originated through hybridizations between the former two forms. In order to infer the phylogenetic affinity of the yellow type from Sado Island, we examined the karyotype and also analyzed the mitochondrial gene sequences. Our results strongly suggested that the yellow type had originated from the ancestral lineage of the Kanto form early in the divergence of R. rugosa in Japan, achieving genetic characteristics of its own. Also, the results suggested distant affinity of the ZW form to the yellow type, despite their geographic proximity.

We investigated the genetic structure of 16 populations (from five geographical groups) of clouded salamander (Hynobius nebulosus) in northern Kyushu, Japan, by analyzing the sequence of the mitochondrial DNA control region. A total of 24 haplotypes were found in 199 individuals of the salamander. In the analysis of genetic diversity of the populations, an isolated small population sustained in an urban area had a low level of genetic diversity. This is considered to be due to both the less suitable nature of the habitat and a recent artificial barrier to gene flow. In the analysis of genetic differentiation (F_ST) among 16 populations, significant differences were detected in 76.7% of all possible population pairs. Analysis of molecular variance (AMOVA) showed that most of the genetic variation was attributed to individual differences within populations, but a significant genetic difference among groups was also detected. This fine-scale genetic differentiation would be formed through genetic isolation (or gene flow) by geographic distance, because strong correlations between genetic F_ST/(1-F_ST) and geographic distances were detected. In 10 northern populations from two adjacent groups that were separated by a small lowland river there is a significant positive correlation between geographic and genetic distance, but there tends to be a larger genetic distance between the inter-group populations than the distance within groups. These results suggest that even a small lowland river, if combined with past rising of sea level by transgression, might be a landscape barrier to gene flow of this species.

Maternal attendance of eggs is a parental care behavior widespread in snakes, but observations under natural situations are limited. During a radio-tracking study in a dry forest in Madagascar, we located a female Leioheterodon madagascariensis that was attending a clutch of eggs in a cavity below ground. The late embryonic stage of an excavated egg and locations of the female recorded before its discovery with the clutch suggest that the female had been attending the eggs for a relatively long period but with occasional intervals when she left the oviposition site.

Skull morphology was compared between juvenile and adult green turtles by geometric morphometrics. The size of the orbit and length of the supraoccipital in relation to the centroid size were larger in juveniles than in adults, while the relative sizes of the infratemporal fossae and parietal were larger in the latter than in the former. The difference in the relative length of the supraoccipital did not predict the maintenance of functional equivalence of trophic structures, probably reflecting a functional trophic change with growth.