Evolution of Nuchal Glands, Unusual Defensive Organs of Asian Natricine Snakes (Serpentes: Colubridae), Inferred From a Molecular Phylogeny

A large body of evidence indicates that evolutionary innovations of novel organs have facilitated the subsequent diversification of species. Investigation of the evolutionary history of such organs should provide important clues for understanding the basis for species diversification. An Asian natricine snake, Rhabdophis tigrinus, possesses a series of unusual organs, called nuchal glands, which contain cardiotonic steroid toxins known as bufadienolides. Rhabdophis tigrinus sequesters bufadienolides from its toad prey and stores them in the nuchal glands as a defensive mechanism. Among more than 3,500 species of snakes, only 17 Asian natricine species are known to possess nuchal glands or their homologues. These 17 species belong to three nominal genera, Balanophis, Macropisthodon, and Rhabdophis. In Macropisthodon and Rhabdophis, however, species without nuchal glands also exist. To infer the evolutionary history of the nuchal glands, we investigated the molecular phylogenetic relationships among Asian natricine species with and without nuchal glands, based on variations in partial sequences of Mt‐CYB, Cmos, and RAG1 (total 2,767 bp). Results show that all species with nuchal glands belong to a single clade (NGC). Therefore, we infer that the common ancestor of this clade possessed nuchal glands with no independent origins of the glands within the members. Our results also imply that some species have secondarily lost the glands. Given the estimated divergence time of related species, the ancestor of the nuchal gland clade emerged 19.18 mya. Our study shows that nuchal glands are fruitful subjects for exploring the evolution of novel organs. In addition, our analysis indicates that reevaluation of the taxonomic status of the genera Balanophis and Macropisthodon is required. We propose to assign all species belonging to the NGC to the genus Rhabdophis, pending further study

The amphibians and reptiles of Mindanao Island, southern Philippines, II: the herpetofauna of northeast Mindanao and adjacent islands

We summarize all available amphibian and reptile species distribution data from the northeast Mindanao faunal region, including small islands associated with this subcenter of endemic vertebrate biodiversity. Together with all publicly available historical information from biodiversity repositories, we present new data from several major herpetological surveys, including recently conducted inventories on four major mountains of northeast Mindanao, and adjacent islands of Camiguin Sur, Dinagat, and Siargao. We present species accounts for all taxa, comment on unresolved taxonomic problems, and provide revisions to outdated IUCN conservation status assessments in cases where our new data significantly alter earlier classification status summaries. Together, our comprehensive analysis of this fauna suggests that the greater Mindanao faunal region possesses distinct subcenters of amphibian and reptile species diversity, and that until this area is revisited and its fauna and actually studied, with on-the-ground field work including targeted surveys of species distributions coupled to the study their natural history, our understanding of the diversity and conservation status of southern Philippine herpetological fauna will remain incomplete. Nevertheless, the northeast Mindanao geographical area (Caraga Region) appears to have the highest herpetological species diversity (at least 126 species) of any comparably-sized Philippine faunal subregion

Observations on the vertebral hypapophyses and associated Musculature in some snakes, with special reference to the Colubridae

Hypapophyses are reported to be present on the anterior precaudal vertebrae of representatives of all snake families, except the Typhlopidae, Leptotyphlopidae, and Uropeltidae. The processes occur on all precaudal vertebrae in the Acrochordidae, Colubridae (auct.), Elapidae, Viperidae, and two subfamilies of the Boidae, the Bolyerinae and Tropidophinae. Among the numerous genera of the Colubridae caudal extent of the presence of the hypapophyses is variable, even within a genus or species. Cope (1864) associated hypapophyses on the posterior precaudal vertebrae with the Homalopsinae. In the years following he utilized the character to distinguish the Homalopsinae (1886), the Colubrinae (1887), the Natricidae (1893); in his last classification (1900), Cope divided the families Colubridae and Dipsadidae into two informal series of genera based on the presence or absence of hypapophyses on the posterior precaudal vertebrae. Boulenger (1893-96) used the presence or absence of posterior hypapophyses in a similar manner to separate the genera of two subfamilies of the Colubridae, the Colubrinae and Dipsadomorphinae. Several authors since have used the character in organizations of the confusing array of colubrid genera (Dunn, 1928; Bogert, 1940; Smith, 1943, who suggested the terms Hypophysia and Anhypophysia for the two basic types; Underwood, 1967). Malnate (1960) suggested a possible evolutionary sequence for the character in the Colubridae. Auffenberg (1963) recommended that more detailed observations be made of the hypapophyses. Rosén (1905a, b) took exception to Boulenger's statements regarding posterior hypapophyses in some genera. Brongersma (1938) reviewed Rosen's work, confirmed his findings, and added that hypapophyses ar

A study of the yellow-lipped snake, Rhadinaea flavilata (Cope)

Volume: 24Start Page: 359End Page: 36

Amphlesma Platyceps (Blyth) and Amphiesma Sieboldii (Guenther): Sibling Species (Reptilia: Serpentes)

Volume: 63Start Page: 1End Page: 1

Interpopulation variation in the colubrid snake Natrix pryeri from the Riukiu Islands, with description of a new subspecies

Volume: 31Start Page: 51End Page: 6