The keeled earless lizard (Holbrookia propinqua) is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of phrynosomatid

Phrynosomatidae

Phrynosomatidae is a diverse family of lizards, found from Panama to the extreme south of Canada. Many members of the group are adapted to life in hot, sandy deserts, although the spiny lizards prefer rocky deserts or even relatively moist forest edges, and the short-horned lizard lives in prairie...

 lizard

Lizard

Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...

.

Geographic range

It is found primarily in Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, in the states of Tamaulipas

Tamaulipas

Tamaulipas officially Estado Libre y Soberano de Tamaulipas is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 43 municipalities and its capital city is Ciudad Victoria. The capital city was named after Guadalupe Victoria, the...

 and Veracruz

Veracruz

Veracruz, formally Veracruz de Ignacio de la Llave officially Estado Libre y Soberano de Veracruz de Ignacio de la Llave , is one of the 31 states that, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided in 212 municipalities and its capital city is...

, but it also ranges to the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, in southern Texas

Texas

Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

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Description

The dorsal scales are small, pointed, and keeled, as the common name implies. The lateral scales are similar but smaller. The ventral scales, which are flat and smooth, are 3-4 times larger than the dorsal scales. Adults may attain 62 mm (2⅜ inches) snout to vent length (SVL), 140 mm (5½ inches) total length.

Subspecies

There are three recognized subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 of Holbrookia propinqua:

• northern keeled earless lizard, Holbrookia propinqua propinqua Baird
  Spencer Fullerton Baird
  Spencer Fullerton Baird was an American ornithologist, ichthyologist and herpetologist. Starting in 1850 he was assistant-secretary and later secretary of the Smithsonian Institution in Washington, D.C...
  
   & Girard
  Charles Frédéric Girard
  Charles Frédéric Girard was a French biologist specializing in ichthyology and herpetology.Born in Mulhouse, France, he studied at the College of Neuchâtel, Switzerland as a student of Louis Agassiz. In 1847, he accompanied Agassiz as his assistant to Harvard...
  
  , 1852
• southern keeled earless lizard, Holbrookia propinqua piperata H.M. Smith & Burger, 1950
• Stone's keeled earless lizard, Holbrookia propinqua stonei Harper
  Francis Harper (biologist)
  Francis Harper was an American naturalist. His research included studies of the Okefenokee Swamp and fieldwork in the north eastern United States and in northern Canada, and he also studied the 18th century American naturalists John and William Bartram...
  
  , 1932