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This study described the detailed osteological features of the Setouchi salamander Hynobius setouchi. H. setouchi, which is endemic to central Japan, was recently delineated from the wide range of H. nebulosus species based on molecular and external morphological characteristics. However, the osteological features of the species belonging to the genus Hynobius have not been examined, which has hindered the detailed understanding of morphological diversity in the genus. To address this problem, this study elucidated the osteological features of the salamander using micro-computed tomography scanning and whole-mount double staining methods. The articular, a part of the hypobranchial I, a part of coracoid, pubis, carpus, and tarsus were cartilaginous in small-sized individuals and were partially or completely ossified in large-sized individuals. The degree of ossification varied in the operculum, basibranchial II, and ascending process of the palatoquadrate. However, ossification was not associated with body size. The lacrimal, ossified manus, and ossified pes exhibited varying degrees of articulation or fusion irrespective of body size. Moreover, the cranium and tarsus of H. setouchi exhibited several unique characteristics. These osteological characteristics will aid in revising the taxonomy and phylogeny of the Hynobius species.

Taxonomic identification of two Taiwanese salamanders, Hynobius sonani (Maki, 1922), and H. formosanus Maki, 1922, was clarified. Based on the descriptions and measurement data in the original description, we confirmed that H. sonani has been treated as H. formosanus and vice versa, which might have been caused by confusion of sampling localities of the two species. Because we could not find the holotypes of the two species and concluded these were lost, we herein assign neotypes for these species for precluding future taxonomic confusion.

The hynobiid salamander genus

The hynobiid salamander genus Hynobius is a basal taxon in the urodeles that plays a key role in understanding the evolution of sexual dimorphism in urodeles. We examined the age (juveniles vs. adults) and sexual differences in the external and skeletal morphology of a Japanese lentic breeding salamander, Hynobius setouchi. We found that juveniles had larger heads than those of adults, and most characters were larger in adult males than in females, except for trunk size. This was also observed in skeletal morphology, although some tail characters differed only in the skeleton. We suggest that intra- and interspecific comparisons of the external and skeletal characters of salamanders should consider age, sexual, and seasonal differences.

Life cycle environmental impact of an electric-assist bicycle has been discussed, and the effectiveness of such bicycle is compared with existing transportation from the viewpoints of carbon dioxide and carbon dioxide equivalent emissions. In life cycle environmental evaluation, in-vehicle fuel cell power generator is applied as an energy source for the electric-assist bicycle as well as commercial purchased electricity. Its transportation with scooter, passenger car and light truck are chosen for comparison. Accordingly, the environmental impact affecting factors of each type of transportation device are shown. As a result, the electric-assist bicycle is found to be effective for short-distance transport of as in a factory or a local transportation.