Mexican Horned Lance Vipers

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Mexican Horned Lance Vipers
Systematics
without rank: Toxicofera
Subordination : Snakes (serpentes)
Superfamily : Adder-like and viper-like (Colubroidea)
Family : Vipers (Viperidae)
Subfamily : Pit vipers (Crotalinae)
Genre : Mexican Horned Lance Vipers
Scientific name
Ophryacus
Cope , 1887

The Mexican Horn Terciopelos ( Ophryacus ) are a snake species from the subfamily of pit vipers . The genus occurs with two species in higher altitudes in the middle east and south of Mexico . The animals inhabit dry bushes, tropical deciduous forests and pine-oak forests with a pronounced dry season, as well as mountain cloud forests . Mexican horned lance vipers are poisonous, but nothing is known about their toxic effects on humans. The German name refers to the striking, horn-like or spike-like elongated scales above the eyes.

features

anatomy

Mexican horned lance snakes are small to medium-sized, relatively powerful snakes. The head is large, broad and clearly set off from the neck. The snout is pointed and the canthus is sharp. The tail is not suitable for grasping. The species have overall lengths of normally 37.5–50 cm, a maximum of 57.8 cm ( O. melanurus ), or 55–70 cm ( O. undulatus ).

Scaling

The rostral is wider than it is high and clearly concave. There are three praeocularia , the upper one of which is significantly larger than the others. The species show 2 to 6 suboculars , 2 to 4 postoculars and 1 to 4 supraoculars . A single supraocular above the eye is elongated into a long, relatively thin spine or flattened horn. Neighboring scales often show slight bumps as well. The scales on the canthus as well as the internasalia can also have short thorns or have particularly high keels. The top of the head is covered with small, mostly warty keeled scales.

The animals have 9 to 20 intersupraoculars . The number of supralabials is 10 to 14, the number of infralabials 9 to 14. The number of ventral scales ( ventral shields ) varies between 141 and 178, the number of subcaudalia divided in O. undulatus and undivided in O. melanurus between 36 and 57 and the number of dorsal scales in the middle of the body is 21.

coloring

The basic color of the upper side is reddish brown, olive brown or gray, with orange, yellow or green coloring components. On the back, the animals show a broad, dark zigzag pattern. On the flanks there are one or more rows of smaller and diffuse spots below. The sides of the head are undrawn or show a not very noticeable dark postocular stripe that extends from the back of the eye to behind the corner of the nose.

distribution and habitat

Mexican horned lance vipers are restricted to altitudes between 1,600 and 2,800 m in the middle east and south of Mexico . The animals inhabit dry bushes, tropical deciduous forests and pine-oak forests with a pronounced dry season, as well as mountain cloud forests .

Systematics

Campbell & Lamar recognize 2 types:

A molecular genetic investigation including both species has confirmed the monophyly of the genus.

Lifestyle, Diet and Reproduction

Both species are probably active during the day due to the low night temperatures. O. melanurus is apparently only living on the ground, O. undulatus , on the other hand, is at least partially tree-living and was regularly found three to four meters above the ground. The previously known food spectrum includes small lizards and mammals . All species are viviparous, young animals are usually born at the beginning of the rainy season. Between 3 and 13 young per litter are proven.

Poison

Mexican horned lance vipers, like all pit vipers, are poisonous, but nothing is known about the poisonous effects on humans.

swell

Individual evidence

  1. ↑ Christoph I. Grünwald, Jason M. Jones, Hector Franz-Chávez Iván T. Ahumada-Carrillo: A new species of Ophryacus (Serpentes: Viperidae: Crotalinae) from eastern Mexico, with comments on the taxonomy of related pitvipers. Mesoamerican Herpetology 1 (1), September 2014 ( full text ).
  2. ↑ Todd A. Castoe, Mahmood M. Sasa, Christopher L. Parkinson: Modeling nucleotide evolution at the mesoscale: The phylogeny of the Neotropical pitvipers of the Porthidium group (Viperidae: Crotalinae). Molecular Phylogenetics and Evolution, Volume 37, Issue 5, 2005: pp. 881-898

literature

  • David A. Warrell: Snakebites in Central and South America: Epidemiology, Clinical Features, and Clinical Management . In: Jonathan A. Campbell, William W. Lamar: The Venomous Reptiles of the Western Hemisphere. Comstock; Ithaca, London. 2004. ISBN 0-8014-4141-2 : pp. 709-761.
  • Jonathan A. Campbell, William W. Lamar: The Venomous Reptiles of the Western Hemisphere. Comstock; Ithaca, London; 2004 ISBN 0-8014-4141-2

Web links