Texas coral snake

Micrurus tener, commonly known as the Texas coral snake, is a species of venomous snake in the family Elapidae. The species is native to the southern United States and adjacent northeastern and central Mexico. Six subspecies are recognized as being valid, including the nominotypical subspecies, Micrurus tener tener The species Micrurus tener was once considered to be a subspecies of the eastern coral snake (Micrurus fulvius).

Geographic range


The Texas coral snake ranges from the southern United States south to northeastern and central Mexico. It inhabits the states of Texas, Louisiana and Arkansas, and the Mexican states of Tamaulipas, San Luis Potosí, Guanajuato, Querétaro and Morelos.

Description
The Texas coral snake has the traditional coloration associated with coral snakes: black, yellow, and red rings. These rings extend onto their belly. It is capable of growing to 48 in (122 cm) in total length (including tail), but most are closer to 24 in. Males are typically smaller than females. It has smooth dorsal scales, a rounded head, and the eyes have round pupils. Albinistic (lacking black pigment) and anerythristic (lacking red pigment) specimens have been found in the wild. "Pastel" (pink, translucent cream, and very light blue) coloration has been noted, and completely black (melanistic) specimens, are known. The Texas coral snake is somewhat larger (longer and stouter) than the eastern coral snake (Micrurus fulvius), and has a somewhat larger venom yield.

Behavior
All coral snakes are shy, secretive animals, typically nocturnal. They spend most of their time hiding in leaf litter, under logs. They can be seen crawling on the surface, after heavy rains, when the nighttime temperatures rise above 78 F.

When grabbed suddenly, or sometimes just when touched, they may thrash about, swing around, and bite. Sometimes they are calm, and then suddenly swing around and bite, for no apparent reason.

Diet
The primary diet of the Texas coral snake consists of other snakes, primarily earth snakes, and other small fossorial species. It is cannibalistic. It also occasionally eats small lizards, but the consumption of rodents by coral snakes is rare.

Reproduction
The Texas coral snake is oviparous.

Mimicry
Other nonvenomous snakes resemble the Texas coral snake as a form of Batesian mimicry. In the United States only, all three species of venomous coral snakes (Micruroides euryxanthus, Micrurus fulvius, and Micrurus tener) can be identified by the red rings contacting the yellow rings. A common mnemonic device is "red and yellow, kill a fellow. Red on black, friend of Jack". However, this mnemonic is not always accurate, due to the aforementioned color variations, and its usage is dangerous to both snakes and humans.

Venom


Coral snakes are proteroglyphous, meaning they have a pair of deeply grooved, semihollow, chisel-shaped, fixed fangs in the front of its upper jaw, through which venom is injected. Though it was previously thought that they to need to gnaw to inject venom, Coral snakes need only a quick bite to deliver a significant amount of venom. Many bites from coral snakes do not inject any venom at all (known as a dry bite).

Texas coral snake venom contains neurotoxin and myotoxin. Bite victims may experience potentially lethal paralysis or myolysis. Immediate first aid measures for a bite can include removing any jewelry on a limb that has been bitten (in case of severe swelling) and wrapping the bite area moderately tightly in a wide cloth; however, the bitten limb should be moved as little as possible. Bite victims should be taken to the nearest hospital as soon as possible for more advanced lifesaving measures, such as application of antivenom.

The Texas coral snake can deliver 10-12 mg of venom in a single bite.

Because of the low profits, the production of coral snake antivenin has been discontinued for several years. Prior to the availability of antivenin, the fatality rate of coral snake envenomations has been estimated at 10%, and death was primarily due to respiratory or cardiovascular failure as a result of paralysis induced by the neurotoxic venom.

Wyeth Pharmaceuticals, a wholly owned subsidiary of Pfizer, produced antivenin for the eastern coral snake, which can also be used for treatment of envenomation by the Texas coral snake. However, the last lot produced (Lot L67530) has an expiration date of January 31, 2020. Pfizer indicates that antivenom is available and one source states that production has resumed.

Subspecies
The six recognized subspecies of M. tener are:
 * M. t. tener (Baird & Girard, 1853)
 * M. t. fitzingeri (Jan, 1858)
 * M. t. bernadi (Cope, 1887)
 * M. t. maculatus Roze, 1967
 * M. t. microgalbineus B.C. Brown & H.M. Smith, 1942
 * M. t. tamaulipensis Lavin-Murcio & Dixon, 2004

Nota bene: A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than Micrurus.

M. t. tener is found in both the U.S. and Mexico, whereas the other four subspecies are endemic to Mexico.

Etymology
Their Latin name tener means "soft of delicate". This is in reference to the graceful features of the snake.

The subspecific name, fitzingeri, is in honor of Austrian herpetologist Leopold Fitzinger.

The name maculatus (Latin for spotted) refers to the presence of some large black spots in the red bands.

The name microgalbineus is derived from a modern Latin adaptation of the original Greek word micro meaning small and tiny and galbineus, Latin for greenish yellow. The name microgalbineus alludes to the short yellowish bands of this subspecies.

Taxonomy
The Texas coral snake was once considered a subspecies of the eastern coral snake, Micrurus fulvius, but more recent research has determined that it has enough morphological differences to be considered its own species.