Current Herpetology

Captive breeding programs are utilized worldwide for the recovery and conservation of endangered species, including the critically-endangered hawksbill turtle (Eretmochelys imbricata). However, aggression is an issue that is commonly reported among captive hawksbill turtles housed together. In the present study, we installed rocks in a captive environment to assess whether they can suppress aggressive behavior in captive hawksbill turtles. The behavior of immature female hawksbill turtles (n=6) was recorded over a 10 d period (between 0900 and 1700 h daily) in an experimental tank under the following conditions: (1) housed alone or paired with another individual in the (2) presence and (3) absence of rocks. Resting behavior was recorded as the total amount of time spent resting per day, while hiding and biting behaviors (i.e., aggressive behavior) were recorded as the total number of events observed per day. Serum corticosterone concentrations were measured at 0900 and 1700 h daily throughout the experimental period. The median number of hiding and biting events was significantly lower for paired individuals housed in the presence of rocks than that for those housed in the absence of rocks. Although no significant differences in serum corticosterone concentrations were observed among the experimental groups, paired individuals spent significantly more time resting in the presence of rocks. Our results suggest that underwater rock installations effectively reduce aggression in captive hawksbill turtles.

The development of lotic-breeding Bufo torrenticola is described from zygote to completion of metamorphosis in captivity at 13±1°C. We delimit 56 developmental stages based on external features. We describe developmental stages so as to be comparable to common stages that are widely used for anurans. We also compare the larval development between B. torrenticola in lotic water and lentic water, and with lentic-breeding B. japonicus formosus in lentic water. Our results suggest tadpole mouth size in B. torrenticola is determined by genetic factors, but the tail muscle volume is determined by both genetic and environmental factors.

Sexual dimorphism and geographic variation are common in snakes. The white-lipped pitviper (Trimeresurus albolabris) is a common and widely distributed venomous snake species throughout the Southeast Asia. We report on the sexual dimorphism and geographic variation of T. albolabris in China. Ninety-nine specimens (57 females and 42 males) were examined by using analysis of variance, analysis of covariance, principal component analysis, and other statistical methods for 68 morphological characters. The result showed that T. albolabris displays significant sexual dimorphism in several external characters. Females have a longer snout-vent length, wider anal scales, and larger head size than males, whilst males exhibit a longer tail length and larger number of subcaudal scales. No significant geographic variation was detected, suggesting the absence of obvious morphological differentiation among local populations in China.

To elucidate phylogenetic patterns in courtship and male-male combat (MMC) behaviors in snakes, I plotted behavioral characters (BCs) onto phylogenetic trees of snakes. For courtship, I plotted 33 BCs onto a phylogenetic tree of 155 snake species in 12 families. For MMC, I plotted 21 BCs onto a phylogenetic tree of 128 snake species in 11 families. For courtship, results suggest the following. Spur Contact and Spur Movement are ancestral for the clade Pythonidae+Boidae and were present as early as the Paleocene Epoch. The Jerk, Chin-Rub, and Dorsal Advance are ancestral for the clade Endoglyptodonta and were present by the late Oligocene. A coital Bite was added in the colubrid clade Zamenis+Lampropeltini by the early Miocene. For MMC, results suggest the following. The Coil, Hook, Type 2 Head Raise, and Downward Push are ancestral for the clade Afrophidia and were present by the early Paleocene. The Type 1 Head Raise replaced the Type 2 Head Raise in Micrurus by the mid-Miocene and in the Lampropeltini by the early Miocene. In the Lampropeltini, Body Bowing was added and Pinning the Head replaced the Type 2 Head Raise by the early Miocene. In addition to written literature, this study utilized a large amount of documentation in the form of video footage on YouTube. For many species, the footage documents behaviors that were unrecorded in the written literature. The results demonstrate that social media can be a highly useful data source in the scientific study of animal behavior.

The number of species of salamanders of the genus Onychodactylus in Japan has increased from one to six nominal species over the past decade, by taxonomic studies based not only on morphological but also molecular phylogenetic data. However, the presence of an additional cryptic species has been suggested by a series of previous studies. Here, we describe a new species, Onychodactylus pyrrhonotus sp. nov., from the Kinki, Chubu and Hokuriku Districts of central Honshu, Japan, based on morphological and genetic evidence. It belongs to the O. japonicus species complex and is the sister species of O. kinneburi from Shikoku Island and westernmost part of Honshu with 5.5% sequence divergence in the mitochondrial cytochrome b gene. The range of the new species completely overlaps with that of O. japonicus sensu stricto, and they are syntopic in at least six known localities. As shown in a previous study, reproductive isolation between these sympatric species is substantial. The new species is morphologically most easily distinguished from congeners by coloration, a sharply defined scarlet to pinkish dorsal stripe or mottling on a black background and dusty white dots on the venter.

The objective of the present study was to explore the reproductive characteristics of the first-generation hybrid crocodile derived from captive Crocodylus siamensis, C. niloticus and C. porosus introduced from Cambodia, South Africa, and Malaysia. The data for 789 eggs and 651 hatchlings in 26 nests of hybrids of three different crocodile species were collected. Statistical analysis of reproductive variables of hybrid crocodile eggs indicated that the characteristic variables were normally distributed except for the hatching rate. Regression analyses were used to develop the linear equation between egg length, egg width, hatching rate, hatchling weight, and egg mass. The results found a significant correlation between egg mass and other traits except for egg shape index. Significant influences of egg mass and the egg shape index on hatching rate were detected. There was no significant linear relationship between clutch size and egg characteristics. There were several differences in the reproductive characteristic variables between hybrid crocodiles of C. niloticus×C. siamensis and their parental species bred in captivity (variables of the hybrid were generally smaller) and between C. siamensis×C. porosus and their parental species (variables of the hybrid were generally larger). However, there was no difference in the reproductive variables between hybrid crocodiles of C. niloticus×C. porosus and their parental species. These results indicate that careful and rigorous scientific assessments are required on the hybridization of endangered species in particular to fully consider the effects of human intervention on hybridization.

Kraits (genus Bungarus) are a group of highly venomous elapid snakes found across tropical Asia. Although they are notorious for causing many, often deadly, envenomations throughout the continent, their taxonomy and species nomenclature is subject to regular revisions. The boundaries demarcating B. candidus, B. multicinctus, and B. wanghaotingi, in Southern China and Northern Myanmar are particularly obscure. Despite the extensively overlapping distributions for the three species, only B. multicinctus has been documented in Hong Kong. Following genetic analyses, we suggest that both B. multincinctus and B. wanghaotingi occur in Hong Kong. However, our morphological examinations are overall inconclusive in distinguishing the two species. With potential interspecific antivenin differences, the new identification of B. wanghaotingi in Hong Kong is of important medical interest. We recommend further ecological, taxonomic, and behavioural studies be conducted to properly distinguish B. multincinctus and B. wanghaotingi in the region.

We developed eight novel microsatellite markers for the salamander Hynobius tsuensis, which is endemic to Tsushima Island, Japan. In H. tsuensis, the number of alleles, observed heterozygosity, and expected heterozygosity in each locus ranged from 1 to 10, 0.00 to 0.76, and 0.00 to 0.76, respectively. In cross-species amplification, five and four of the eight loci were successfully amplified for all individuals of Hynobius sp. from Tsushima and H. nebulosus, respectively. Three species of Hynobius were clearly split from each other in the STRUCTURE analysis, indicating genetic differentiation in nuclear DNA among three species. This is the first report on genetic variation between two close relatives, Hynobius sp. from Tsushima and H. nebulosus based on nuclear loci. These novel markers will be useful for elucidating intraspecific variations and inferring conservation units within H. tsuensis, and studying intra- and inter-specific variations in other Hynobius.

We uncovered the phylogenetic origins of the Japanese red-bellied newt (Cynops pyrrhogaster) population newly found in Yokohama city and 11 neighboring populations in Kanagawa Prefecture based on mitochondrial NADH6-tRNAGlu-cytochrome b DNA sequences. The Yokohama city population was found to be an alien population introduced from Western Japan. On the other hand, the other populations we investigated belong to either of two genetic lineages of the newt (CENTRAL and NORTHERN), and they are distributed parapatrically around the foot of the Tanzawa Mountains.

Life history parameters are essential when we consider appropriate strategy for conservation of wildlife based on population dynamics modelling. In this study, life history stage and sex-specific survival rates of a Japanese pond turtle (Mauremys japonica) population in foothill region were estimated. Life history was divided into three stages based on the age, separately for males and females, estimated by counting the number of annual rings on scutes: juvenile (1–2 years old), young adult (3–4), and adult (>5) in males, and juvenile (1–4), subadult (5–7), and adult (>8) in females. The median annual survival of subadult and adult females was 0.84 (95% credible interval: 0.54–0.99) and 0.94 (0.77–1.00), respectively, and higher than the survival of juvenile females. In contrast, adult survival of males was estimated as 0.79 (0.44–0.99), and it was higher than the survival of young adult and juvenile males. This study showed that the patterns of survivorship of M. japonica coincide with those of other chelonians.