Discovery of Nucho-Dorsal Glands in Rhabdophis adleri

Abstract: The nuchal and nucho-dorsal glands are unique defensive organs that have been found in only 13 species of Asian natricine snakes. In Rhabdophis such nuchal glands have been described in nine species, whereas the absence of the glands has been also reported in a few species, including R. adleri. We reexamined the absence/presence of the nuchal glands ofR. adleri by dissection of two freshly dead individuals and a recently preserved specimen, as well as by careful reobservation of six type specimens, in which the absence of the glands had been reported. The glands were found both in the neck and along the entire length of the body in the three new specimens. We also confirmed the presence of the glands, at least in the anterior part of the body, in three type specimens. We conclude that the glands were simply overlooked in the original description and that R. adleri possesses nuchodorsal glands that extend over the full length of the body, including the neck region.