Male Hynobius leechii (Amphibia: Hynobiidae) Discriminate Female Reproductive States Based on Chemical Cues

A series of no-choice olfactory response tests using water pre-conditioned with females, with intact and surgically removed ventral glands, at various reproductive states were conducted to determine whether male Hynobius leechii discriminates among females in different reproductive states based on chemical cues. Similarly, ventral gland extracts were tested, and ventral glands were examined histologically. Males’ responses to putative odors of females in four (ovulating, ovulated, ovipositing, and oviposited) reproductive states were independently measured by: i) the latency time to initiate male behavioral response, ii) the arrival time at a fixed point of putative odor source, and iii) the staying time close to the odor point source. Male salamanders showed significant olfactory responses to recently ovulated and ovipositing female odors by quickly arriving at odor sources and staying longer at the origin of the source, but the olfactory responses to the earlier staged ovulating females and the later stage of already oviposited females were not different from controls. Olfactory responses of test males to water preconditioned by intact females or females with ventral glands excised were not different. In addition, ventral gland extracts did not induce significant olfactory responses of test males although the lumens of alveoli in ventral glands of oviposited females were smaller than those of ovulated females. These results indicate that male H. leechii recognizes ovulated and ovipositing females based on chemical cues released but not from the ventral glands.