Current Herpetology

Cannibalistic behaviour in seven Salamandra salamandra infraimmaculata half-sib cohort larvae (each born to a single female and at the same time) and in juveniles was studied under different food and density conditions. The level of cannibalistic behaviour (tails bitten off or larvae eaten) changed as the larvae grew, from a low level during the first week to a peak at five weeks, regardless of differences in mass between the experimental larvae. No cannibalistic behaviour was observed in post-metamorphic salamanders even if they were cannibalistic as larvae. Significant differences in levels of cannibalism were found among different cohorts. Whereas in one cohort only 7% of the larvae were cannibalistic, in another, the cannibalism level peaked at 70% thereby indicating a possible maternal effect. However, cannibalistic behaviour in salamander larvae was apparently not related to the mother's age. The effect of food and density on cannibalism seems to be indirect or of secondary importance. Thus, cannibalism level was similar when food was scarce or when fed ad-libitum, whereas larvae offered a high level of food were significantly more cannibalistic. This could indicate that an optimum food level triggers cannibalism. When food becomes abundant the need for cannibalism ceased to persist. Under xeric conditions, ponds dry out rapidly; consequently rapid development through cannibalism results in earlier metamorphosis essential for this species' survival because of the limited time for dispersal of juveniles.

We surveyed allozymic variation among Hynobius naevius from 11 localities of central Kyushu, Japan. The results revealed the presence of two genetic groups (I and II) that exhibited a great difference in allelic frequency and a large genetic distance. Specimens from seven of the 11 localities invariably belonged to Group I, and those from three other localities belonged to Group II. In the remaining one locality, representatives of both of these two groups were found just as in northern Kyushu. The two genetic groups also differed in morphological (Group I larger than Group II in body size) and ecological characters (breeding sites located in open streams in Group I, but possibly in underground water in Group II). These differences might have been enabling them to coexist.

Embryonic mortality and clutch size of the foam-nesting treefrog Rhacophorus arboreus were observed in early summer of 2000 and 2001 at a small pond in a secondary forest on the campus grounds of Tokyo Metropolitan University. A total of 24 foam nests were monitored from just after spawning. When hatchlings emerged, the foam nests were collected and examined for embryonic mortality and clutch size. Embryonic mortality, averaging 0.233 (0.036–0.616, SD=0.173), varied markedly among nests. Logistic regression showed that the date of spawning had a significant effect on embryonic mortality: the nests constructed late in the season suffered higher mortality. Clutch size varied from 272 to 872 (x̄=522.1, SD=134.0). Multiple regression analysis showed that year and date of spawning had no significant effect on clutch size. A significant correlation was detected between clutch size and height of the nesting position (r=−0.563, P=0.004): those nests constructed higher above the pond water tended to have smaller clutches. Factors affecting egg mortality and clutch size are discussed.

Suitability of different food items for tadpoles of the Japanese toad (Bufo japonicus formosus) was studied by rearing experiments. Tadpoles were fed single food items (leaf litter, algae, or sludgeworms) individually in the laboratory, and their survival, growth, and development were compared. All individuals metamorphosed successfully. Litter-fed tadpoles metamorphosed at a significantly smaller size than algae- or worm-fed tadpoles, but the latter two metamorphosed at a similar size. The larval period showed little difference among the three food treatments.

Rhacophorus notater Smith, 1924, described from a single juvenile, is regarded as conspecific with R. annamensis Smith, 1924. Both species were described from the same locality in Vietnam. Although the name R. notater appears before R. annamensis in the same publication, R. annamensis is more popular in name among herpetologists, and its biological details are better clarified than those of R. notater. Thus, I propose to treat R. notater as a junior synonym of R. annamensis.

Gehyra veriegata ogasawarasimae was described in 1930 from Chichijima Island of the Ogasawara Group, Japan, and then was reported to have 2n=63 chromosomes in 1949. Subsequently this taxon was synonymized with Lepidodactylus lugubris, a parthenogenetic species complex consisting of a number of diploid-triploid clones distributed in tropical Pacific and Indian Ocean islands. The above chromosome number, as well as dorsal color pattern of an individual illustrated in a figure of its original description, suggests that the type of G. v. ogasawarasimae (lost) belonged to a triploid clone of L. lugubris. However, all L. lugubris recently collected from Chichijima Island and another island of the Ogasawara Group had only 2n=44 chromosomes and belonged to a diploid clone, so-called clone A. A survey of museum specimens of L. lugubris collected from Chichijima Island during 1960–1970s yielded three specimens showing dorsal pattern characteristic of a triploid clone, so-called clone C. These suggest that the triploid clone C previously occurred on Chichijima Island and was erroneously described as Gehyra variegata ogasawarasimae. This clone may have been displaced by the diploid clone A through interclonal competition after recent colonization of the latter to Chichijima and other Ogasawara islands.