I examined the stomach contents of the salamander Hynobius tokyoensis during the winter and the spring breeding season in the Pacific coastal hilly area of central Japan. My observations indicated that this salamander continues to feed throughout the year in at least parts of the coastal area. Soil animals were utilized as prey items in the winter and in the breeding seasons, but males in the breeding season also preyed on aquatic animals. Hynobius tokyoensis is strictly terrestrial during the non-breeding season and predation on aquatic animals by the males is suggested to occur only during the breeding season.
The iguanid lizard, green anole Anolis carolinensis, has currently established breeding colonies on several tropical and subtropical Pacific islands. In the Ogasawara Islands, predation by the green anole has collapsed the endemic insect community. Now that the Ogasawara Islands have been inscribed on the World Heritage List as a natural heritage by UNESCO, it is necessary to study the current status and ecological aspects of the green anole there to improve the effectiveness of control efforts. When planning population management for an alien species, information regarding its fecundity (number of eggs laid per female per year) is essential. This species lays only one egg at a time, but lays multiple times during an extensive reproductive season each year. It is therefore difficult to estimate fecundity by ordinary methods, such as gonadal examination by necropsy. In the present study, we maintained 10 female anoles from Chichijima Island in indoor captivity under conditions similar to those of the Ogasawara Islands to record their egg-laying conditions. Egg-laying occurred from April to October with a peak in August, during which each female laid 0.95 eggs/week on an average. The average number of eggs laid by a female in a year was 13.7. Sites selected for laying were spaces between the leaves of ferns and in hollows on the ground. We consider that for efficient control of this species, we should intensively hunt females in April, before their egg-laying frequency begins to increase.
The chromosomal location and size of the 18S–28S ribosomal RNA (rRNA) gene cluster was examined by fluorescence in situ hybridization (FISH) and AgNO3 banding in three species of the Asian salamander family Hynobiidae: Hynobius quelpaertensis (2N=56), H. tsuensis (2N=56), and Onychodactylus koreanus (2N=78). These species have karyotypes that contain numerous microchromosomes and are thought to resemble the karyotype of the most recent common ancestor of all living caudate amphibians. In the Hynobius species FISH signals representing 18S–28S rDNA sequences were found on multiple single chromosomes as well as on a single homologous pair of micro-chromosomes (no. 23). Co-localization of AgNO3 bands was found on the same pair of microchromosomes indicating that this site represents transcriptionally active NORs (Ag-NORs). Onychodactylus showed FISH signals on an unidentified pair of microchromosomes, but these did not show AgNO3 bands, which were found only on several macrochromosomes and microchromosomes. These results suggest that 1) an active NOR located in a single pair of micro-chromosomes may have been shared by the common ancestor of hynobiids; 2) FISH revealed the presence of rDNA sequences in a similar-looking pair of microchromosomes in Onychodactylus, although the site seems to be Ag-negative; and 3) the similarity of chromosomal localization of the rDNA sequences between Onychodactylus and Hynobius suggests that the location of 18S–28S rDNA sequences on a pair of microchromosomes may be a common feature in the asymmetrical bimodai (AB) karyotypes of hynobiid salamanders.
I describe a new frog of the microhylid genus Hylophorbus from the north-coast mountain ranges of Papua New Guinea that is unique in its small size, continuous black lateral band bordered below by a white line and then a field of whitish gray, and other morphometric and color-pattern features that distinguish it from its two most similar congeners, each also possessing a black lateral band. The new species is one of the two smallest species in the genus. It is currently known only from two of the easternmost north-coast mountain ranges, although it seems likely to occur in nearby mountain ranges to the west, a distributional pattern that is common among endemic amphibians from this region.
A rhacophorid frog from Borneo is divergent genetically and morphologically from Javanese R. reinwardtii, with which it was formerly confused, and is recognized as a distinct species. The frog differs from R. reinwardtii by an immaculate green dorsum and a black posterior thigh surface, which is studded with sky blue spots in the female. Because the frog is also divergent genetically and morphologically from the other congeners recently split from R. reinwardtii, we describe it as a new species, R. borneensis.
An analysis of the microhabitat preference of the Alishan salamander (Hynobius arisanensis) was conducted in the Alishan area of Taiwan from 2003 to 2006. The study consisted of two parts: one to record microhabitat use of salamanders, and the other to quantify suitable microhabitat in the study site. The salamanders were found to use most of the microhabitat types available to them in the study site. However, they used rocks as shelters at a high frequency (77.7%). Although decayed logs were less available than rocks, the salamanders seemed to choose the logs as shelters. The decayed logs can keep moisture for a longer time and provide more prey than rocks, which probably causes the salamanders to choose less-available logs. The salamander preferred large rocks, but showed no preference for the size of logs. They also liked the cover objects with mosses growing on them. As for substrates, soil and plant debris were used most frequently. Salamanders were found negatively associated with live plant roots. Plant roots growing profusely under the cover objects are difficult for the salamanders to pass. The Alishan salamander preferred substrates with neutral substrate pH (6.2–7.0), high substrate moisture (70%–90%), and moderate substrate hardness (10–15). These results show that when information on microhabitat availability is taken into consideration, the real microhabitat preference of the salamanders does not agree with the descriptive results. We suggest that a quantitative approach should be taken for a habitat preference study, and that this information will be very useful for habitat restoration.
The two laticaudine sea kraits, Laticauda laticaudata and L. semifasciata, are distributed in the tropical waters of the western Pacific and the northernmost limit of their breeding populations is considered to be the Northern Ryukyus, Japan. These two species, however, have been occasionally reported from the main islands of Japan, which are located further north. To determine the origins of such individuals, we examined partial sequences of the mitochondrial cytochrome b gene of one specimen of L. laticaudata from Yamaguchi and two specimens of L. semifasciata from Oita and Mie. Comparisons of the sequences with published data for apparently stable populations in the Ryukyu-Taiwan region revealed that sequence of the Yamaguchi specimen was identical with a haplotype previously detected from a broad range of the Ryukyu-Taiwan region and we could not specify its origin. Sequences of the Mie and Oita specimens were identical with, or very close to, haplotypes detected only from the Central Ryukyus and the Southern Ryukyus-Taiwan region, respectively. These results indicate that they were drifters from the Central Ryukyus and further south, corroborating the unconfirmed belief that sea kraits found on the main islands were accidentally transported by the Kuroshio Current from the south. Considering that both species exhibit certain degree of genetic differentiation among island groups in the Ryukyu-Taiwan region, the putative transportations by the Kuroshio seldom contribute to effective gene flow among local populations. The Kuroshio probably poses threats to their survival as the current may carry individuals out of their habitats and distributional range.
Japalura polygonata is an arboreal agamid lizard native to the subtropical East Asian islands. Recent studies reported that this species had been introduced to southern and southeastern Kyushu, Japan. Here, we report that this species has also been introduced to Yakushima Island, a Natural World Heritage site located between Kyushu and Amamioshima Island (the northernmost extremity of its native range). Morphological examination of the Yakushima specimens revealed that this lizard population belongs to the nominotypical subspecies (J. p. polygonata), which is endemic to the Amami and Okinawa Groups of the Central Ryukyus, Japan. Observations of the gonadal condition revealed that females collected in April and June possessed shelled eggs in their oviducts. A few juveniles collected in late April and early August were considered hatchlings based on their body size. These lines of evidence strongly suggest that J. p. polygonata has already established a breeding colony on Yakushima Island. Based on the result of tree censuses, the forests where the lizards were found are classified as secondary forests with a primary component.
We assessed the taxonomic relationship of Pachytriton changi Nishikawa, Matsui et Jiang, 2012 and P. xanthospilos Wu, Wang et Hanken, 2012 using partial mitochondrial DNA sequence and found them to be so closely related as to be regarded as conspecific. This result, together with available morphological information, strongly indicates that P. xanthospilos is a subjective junior synonym of P. changi. By this synonymization, southern Hunan and northern Guangdong provinces are shown to be a part of the natural distribution range of P. changi, whose type locality is known only as China. However, known localities in this range are restricted and endangered status of the species is not changed.
A new striped Ichthyophis is described based on one adult male collected from the southeastern slope of Mt. Kinabalu, Sabah, East Malaysia. The new species is characterized by the absence of yellow marking on the jaw angle and the presence of a lateral stripe on most of the collar region, and is distinguished from all other striped congeners by a combination of characters that includes body size and proportion, position of tentacles, shape of annular grooves, and number of annuli, scale rows, and splenial teeth. The anterior phallodeum morphology is also described for the new species.
Chalcides viridanus is a small skink endemic to Tenerife, the Canary Islands. This paper describes its annual reproductive cycle and sexual dimorphism by use of data from external measurements, dissection, and histological observation of gonads from monthly samples. Males were significantly larger than females in head–forelimb length, distance between forelimbs and hind limbs, tail width, and body mass. Male testes were largest in March, when most individuals showed active spermiogenesis, although no spermiation was observed. In April, the testes were somewhat smaller but showed seminiferous tubules and epididymis ducts with abundant sperm. In this month, female gonads and ovarian follicles were significantly enlarged, and vitellogenesis was evident. Oviductal embryos were found in May and June, and parturition took place at the beginning of August. Both testis mass in males and diameter of the largest oocyte in females were significantly correlated to abdominal fat body mass. We conclude that in C. viridanus both sexes exhibit seasonal changes in gonadal activity with synchronous development of both male and female gonads in the spring months.
A new species of the subgenus Vibrissaphora in the genus Leptobrachium is described from eastern Laos, on the basis of molecular and morphological evidence. The new species differs from all members of the subgenus by lack of spines on upper lip, small size with adult male SVL of 55.2 mm, indistinct tympanum, first finger longer than fourth, inner metatarsal tubercle smaller than first toe, 2⅓ phalanges of fifth toe unwebbed, dorsum nearly smooth and flanks with densely granulated skin, dorsum light brown with dark brown spots, flanks dark brown reticulated with cream spots, and abdomen cream with irregular brown markings. Classification of two subgenera in Leptobrachium is discussed.
In order to estimate the structure of the loggerhead turtle assemblage in Okinawan waters, we measured the straight carapace length (SCL) and sexed 35 loggerhead turtles captured by set net between 2007 and 2011. Sexual maturity in females was determined on the basis of plasma triglyceride, cholesterol, total protein, and calcium concentrations. Of the 35 captured loggerhead turtles, 18 turtles were identified as males based on their elongated tails, while 16 turtles were identified as females in the process of vitellogenesis based on highly elevated blood plasma levels. Only one turtle with low plasma measurements was of indeterminate sex. We suggest that blood plasma measurements may serve as a useful indicator of female maturity. SCL means were 865±48 mm (mean±SD) for all turtles, 865±47 mm for males, and 871±52 mm for females; the turtle of unknown gender had an SCL of 791 mm. The loggerhead turtle assemblage in Okinawan waters was found to be larger in SCL and higher in the frequency of mature individuals than those in conspecific assemblages in other areas of Japanese waters so far studied. We suggest that the loggerhead turtles migrating to Okinawan waters are primarily in active reproductive states in preparation for mating and nesting.
The mitotic karyotype of Ichthyophis kodaguensis consists of 2N=42 chromosomes (FN=60) including nine pairs of sub- and metacentrics and twelve pairs of acrocentrics. Conspicuous blocks of C positive bands were observed in the centromeric regions of all constituent chromosomes. Karyotypic comparison with related species indicated species-specificity of pericentric inversion.