Authors: S. Carranza , E. Nicholas Arnold , Richard H. Thomas , J. A. Mateo And L. F. López-jurado

Authors: Masahiro Saka

Abstract: Acute toxicity tests were carried out on five species of Japanese amphibian larvae, at different developmental stages, to assess the risk posed by thiobencarb, a component of rice paddy herbicides. Test substances were four types of commercially formulated herbicide containing mainly thiobencarb, and the 24 h, 48 h, 72 h and 96 h LC₅₀ (median lethal concentration) values of these herbicides were calculated by probit analysis. These values ranged from 0.9 to 6.5 mg/I of thiobencarb. Newly hatched larvae seemed to be slightly more resistant to the herbicides than well-developed larvae in all test species. There were no clear interspecific differences in responses. The actual thiobencarb concentration in paddy water was measured with indoor models for two weeks, and it ranged from Xenopus laevis produced approximately the same LC₅₀ values as those of Japanese amphibians. This indicates that experimental frogs such as Xenopus laevis can act as a model for these native and wild amphibians when toxicity tests are conducted.

Keywords: Japanese amphibians, herbicide, thiobencarb, acute toxicity, risk assessment

Authors: Jean Baptiste Ramanamanjato , Ronald A. Nussbaum And Christopher J. Raxworthy

Abstract: Mabuya vezo is described as a new white-spotted species of the aureopunctata-group of Madagascan mabuyas, identified by its small size and the presence of regularly arranged rows of white spots on the dorsal and dorsolateral surfaces of the neck, body, and tail. It is known from a single locality, Lavenombato, near the mouth of the Onilahy River in south-western Madagascar. M. vezo is a rock-dwelling species, similar in size and habitat to M. vato, and in general coloration to the much larger M. aureopunctata. M. vezo is broadly sympatric with only one member of its species-group, M. aureopunctata, but two species of the elegans-group, M. elegans and M. gravenhorstii, occur in the same area. The type locality of M. vezo is "fady" (taboo), which provides some degree of protection for this species, which is known from only seven specimens.

Keywords: Scincidae, Mabuya, new species, systematics, Madagascar

Authors: Carlos Frederico Duarte Rocha And Davor Vrcibradic

Abstract: The reproductive cycles, fat body cycles and some life-history traits of the sympatric viviparous skinks Mabuya macrorhyncha and M. agilis were compared in a seasonal "restinga" habitat of south-eastern Brazil. Both male and female reproductive and fat body cycles are very similar between species, with gestation lasting 9-12 months and parturition occurring during the early wet season. Clutch size of M. macrorhyncha was smaller than that of M. agilis. Females mature at a larger size in M. macrorhyncha than in M. agilis, but males of both species appear to mature at similar sizes. In both species, females are larger than males, but the latter have proportionately larger heads. Reproductive traits of M. agilis are typical of Neotropical Mabuya, but those of M. macrorhyncha have some peculiarities, one of which (small clutch size) is believed to result from constraints imposed by its morphological adaptation (i.e. relatively flattened body plan) to bromelicolous habits.

Keywords: Reproduction, life history, Mabuya, Brazilian skink

Authors: John M. R. Baker And Tim R. Halliday

Abstract: Newly constructed ponds on farm land were surveyed for amphibians and compared with long-standing farm ponds. The frequencies of amphibian occupation of the two pond types were similar (65 and 71% respectively), but the species composition differed. Bufo bufo was found more frequently in new ponds than in old ponds, whereas Triturus cristatus and T. vulgaris were found less frequently in new ponds. The differences in the amphibian species assemblage between the two types of pond reflected the ponds' functions and the amphibians' dispersal abilities. New ponds were larger and tended to support fish and waterfowl more frequently than did old ponds. Triturus cristatus was not found in any fish ponds. Principal component and discriminant analyses of variables related to ponds and the surrounding terrestrial habitat indicated that, for T. cristatus and T. vulgaris, the location of new ponds relative to existing ponds was a significant factor in pond colonization. Triturus cristatus and T. vulgaris did not colonize ponds at distances greater than 400 m from existing ponds. Rana temporaria and Bufo bufo were not so constrained by dispersal abilities and were able to colonize new ponds at distances up to 950 m from existing ponds. Rana temporaria was more likely to be found in new ponds containing submerged vegetation; however, multivariate analyses could not discriminate between ponds that were, and were not, colonized by Bufo bufo. The results of this study are discussed with regard to the construction and management of ponds for the conservation of these amphibians.

Keywords: amphibian assemblages, farm ponds, colonization, habitat characteristics

Authors: Michael B. Thompson And Kylie J. Russell

Abstract: We measured water contents, gro wth of embryos and metaboli c rates in hard-shelled eggs of the Australian gecko, Phyllodactylus marmoratus, throughout incubation to make comparisons between (I) the proportional water content at oviposition of eggs of P. marmoratus and flexible-shelled eggs of lizards; and (2) the dry-mass specific energy consumption during development in P. marmoratus and lizards with flexible-shelled eggs. Egg contents (i.e. excluding eggshell) contained nearly 80% water, higher than reported for any other squamate reptile. Eggs were laid at embryonic stages 26/27-29, which is slightly earlier than for most other lizards. Incubation lasted 79-84 days at 25 °C and net water loss averaged just under 3 mg. Metabolism reflected the size of embryos, with little growth and lo w rates of oxygen consumption during the first third of incubation. Thereafter, growth and oxygen consumption in creased, with oxygen consumption slowing after day 70. This pattern is similar to that of other species of lizard. Water content of embryos fell from above 90% early in incubation to around 70% at hatching. Thus, the embryonic metabolic scaling factor was different when based on embryonic wet and dry mass. The dry-mass specific energetic cost of development in P. marmoratus was lower than other lizards, but this result was not related to having a hard-shelled egg. The respiratory exchange ratio suggests that embryonic metabolism is based on mixed protein and lipid, a pattern similar to that in flexible-shelled eggs of lizards, but different from birds.

Keywords: Phyllodactylus, gecko, embryonic development.