The western keeled snake (''Pythonodipsas carinata'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

snake Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more j ...

in the family Pseudaspididae. It is native to western Namibia, southwestern Angola, and southwestern Zambia, and is the only member of the genus ''Pythonodipsas''.

Taxonomy

''P. carinata'' is most closely related to '' Pseudaspis cana''. Together these two monotypic genera make up the subfamily Pseudaspidinae of the family

Lamprophiidae The Lamprophiidae are a family of snakes found throughout much of Africa, including the Seychelles. There are 89 species as of July 2022. Biology Lamprophiids are a very diverse group of snakes. Many are terrestrial but some are fossorial (e.g. ...

. ''Pythonodipsas'' closely resembles the colubrine genus '' Spalerosophis'', although the two are not closely related.

Description

''P. carinata'' is unusual in possessing greatly fragmented head shields, a peculiar maxillary dentition (3rd to 6th largest, posterior-most tooth large and grooved), a reduced number of palatine teeth (including a greatly enlarged "fang"), and hypapophyses developed throughout the vertebral column. It was once thought to be a possible evolutionary intermediate between

vipers The Viperidae (vipers) are a family of snakes found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, and various other isolated islands. They are venomous and have long (relative to non-vipers), hinged fangs th ...

and non-venomous colubroids, but it is now known not to be closely related to vipers.

Behavior

''P. carinata'' are nocturnal.

Diet

''P. carinata'' eat vertebrates, with lizards comprising 67% of the diet, rodents 25%, birds 4%, and unidentified vertebrate bones 4%. Among lizard prey, geckos (39% of all prey) and skinks (18%) predominated. Both nocturnal (''Afroedura'', ''Chondrodactylus'', ''Palmatogecko'' and ''Pachydactylus'') and diurnal geckos (''Rhoptropus'' and ''Narudasia'') were eaten. All skink prey were ''Mabuya'' sp. Mammalian prey were eaten primarily by larger snakes.

Distribution and habitat

''P. carinata'' is a rare snake restricted to gravel plains and arid savannah.

Reproduction

''P. carinata'' lay eggs. Females probably mature between 47.5 and 51.0 cm snout-vent length, and males between 29.0 and 31.0 cm snout-vent length. Juveniles are born at sizes between 16 and 18 cm.

References

{{Taxonbar, from=Q13583140 Snakes of Africa Monotypic snake genera Pseudaspididae Taxa named by Albert Günther