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

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...

in the family

Pseudaspididae Pseudaspididae is a small family (biology), family of Elapoidea, elapoid snakes, containing only two species (each in their own Monotypic taxon, monotypic genus) from sub-Saharan Africa. They were formerly placed as a subfamily of the Lamprophiid ...

. 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 The mole snake (''Pseudaspis cana'') is a species of snake. It has been placed in the family Lamprophiidae, and more recently in the family Pseudaspididae, along with the genus ''Pythonodipsas''. It is native to much of southern Africa, and is t ...

''. 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 Seychelles. There are 89 species as of July 2022. Biology Lamprophiids are a diverse group of snakes. Many are terrestrial but some are fossorial (e.g. '' Ambly ...

. ''Pythonodipsas'' closely resembles the colubrine genus ''

Spalerosophis ''Spalerosophis'' is a small genus of snakes in the Family (biology), family Colubridae. Geographic range Member species are found in a wide range throughout South Asia, Southern Asia, the Middle East, and North Africa. Species The following s ...

'', 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 Vipers are snakes in the family Viperidae, found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, New Zealand, Ireland, and various other isolated islands. They are venomous and have long (relative to non-viper ...

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