Abstract2_3 (Hasumi)

Hasumi, M., and M. Kakegawa: Mixed oviposition of the sympatric salamander species, Hynobius nigrescens and Hynobius lichenatus. Nippon Herpetological Journal 37: 1-9, September 1989. (In Japanese with English abstract)

Abstract: A premating isolating mechanism was discussed based on our investigations on the development of embryos in some sites of mixed oviposition of the sympatric salamanders, Hynobius nigrescens and H. lichenatus. Kawamura (1953) demonstrated in the genus Hynobius that in hybridization between sympatric species embryos died during early development (postmating isolating mechanism). A natural example of this mechanism was found in a pond (approximately 3 m² in area; 1012 m elevation). At the end of the breeding season (1 June 1986), the pond possessed an egg sac of H. lichenatus deposited among more than 500 pairs of egg sacs of H. nigrescens. Fifteen embryos in the egg sac all died out by a late neural-fold stage. On the other hand, in other populations examined in relatively low density the development of embryos progressed normally in both species in which the breeding periods overlapped. This suggests that in a site of mixed oviposition of the sympatric species individual salamanders can distinguish usually their kin (species recognition), perhaps through a pheromone secreted from the cloacal gland.