The Short-tailed Snake (Stilosoma extenuatum) is a small harmless colubrid

Colubrid

A colubrid is a member of the snake family Colubridae. This broad classification of snakes includes about two-thirds of all snake species on earth. The earliest species of the snake family date back to the Oligocene epoch. With 304 genera and 1,938 species, Colubridae is the largest snake family...

 snake. Fossorial and seldom seen, it is found only in sandy, upland parts of Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

 where it is listed as Threatened and is protected by state law. It is usually considered to be the sole member of the genus Stilosoma which dates to the late Miocene and is included with milk snakes in the colubrine tribe Lampropeltini.

Etymology

The short-tailed snake's tail comprises less than ten percent of the snake's total length, hence the common name. Named by A. Erwin Brown in 1890, Stilosoma extenuatum derives its generic name from the Greek stylos for pillar and soma for body. This refers to the stiffness of the short-tailed snake's body, which is caused by its wide and inflexible column of unusually short vertebrae. The specific name, extenuatum, is Latin for thin or slender.

Physical description

The short-tailed snake is a small serpent averaging 36-51 cm (14-20 inches) with a record measurement of 65.4 cm (25¾ inches), and is perhaps as thin as a pencil. It is gray above with 50 to 80 dark blotches and may or may not have a yellow stripe running down the spine. The underside is white with dark brown blotches. It bears a more-than-superficial resemblance to the kingsnakes, especially the mole kingsnake (Lampropeltis calligaster rhombomaculata

Lampropeltis calligaster rhombomaculata

Lampropeltis calligaster rhombomaculata known commonly as the mole kingsnake or brown kingsnake is a subspecies of the prairie kingsnake .-Geographic range:...

), but can be distinguished by its smaller size and much more slender build. Also, Stilosoma extenuatum has 6 upper labials, whereas kingsnakes (genus Lampropeltis) have 7 upper labials.

Behavior

The short-tailed snake is as poorly understood as it is seldom-seen, rare and geographically limited. It is a burrowing snake that rarely appears above ground and does so even more rarely during the day. Like other snakes of the tribe Lampropeltini, it vibrates its tail when startled by predators or people but can be distinguished from a rattlesnake by its slender build and lack of rattle. An excitable snake, it makes a poor captive and is protected against harassment or captivity by Florida law. Despite this, much of what little we know about the short-tailed snake has been based on observations of captive specimens.

Diet

Captive specimens show a keen preference for black-crowned snakes of the genus Tantilla

Tantilla

Tantilla is a large genus of harmless colubrid snakes which includes 64 species commonly known as centipede snakes, blackhead snakes, and flathead snakes.- Description :...

and will often eat them exclusively, rejecting other species of small snake or lizard. It is possible that black-crowned snakes, some of which are themselves small, burrowing snakes endemic to Florida, comprise the entire diet of wild short-tailed snakes.

Habitat and range

Found only in a handful of counties in central Florida, the short-tailed snake prefers sandy-soiled, pine or oak woodlands but may be found in other habitats provided it has access to prey suitable soil for burrowing.

Evolution and taxonomy

As a member of the Lampropeltinine tribe, Stilosoma is ultimately derived from Old World rat snakes that crossed the Bering Land Bridge into North America more than 20 million years ago. More recently, Stilosoma is a relict of the Miocene "Florida Island", separated from the mainland by higher sea levels. It is closely related to the kingsnakes and still bears a resemblance to the mole kingsnakes which are also found in Florida. One fossil species, Stilosoma vetustum dates from the late Miocene, some 5-10 million years ago. How far divergent Stilosoma is from its kingsnake ancestors is still a matter of debate. In 2009 Alex Pyron and Burbrink resolved to include it in the kingsnake genus Lampropeltis based on multiple lines of molecular and morphological evidence.

External links

• Fossil snakes of North America: origin, evolution, distribution, paleoecology
• http://reptile-database.reptarium.cz/species.php?genus=Lampropeltis&species=extenuatum