Assiminea pecos is a rare 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 snail

Snail

Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

 in the family Assimineidae

Assimineidae

Assimineidae is a family of minute snails with an operculum that live in saltwater, freshwater or on the land; they are mostly aquatic gastropod mollusks or micromollusks, in the clade Littorinimorpha.- Ecology :...

 known by the common name Pecos assiminea. It is native to New Mexico

New Mexico

New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...

 and 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...

 in the United States. Specimens known from Mexico are now treated as members of a separate species, Assiminea cienegensis. The Pecos assiminea was federally listed as an endangered species

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 of the United States in 2005.

This snail was first described in 1987. It is generally between 1 and 2 millimeters long. Little is known about its life history

Biological life cycle

A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...

.

This tiny snail lives in the Pecos River

Pecos River

The headwaters of the Pecos River are located north of Pecos, New Mexico, United States, at an elevation of over 12,000 feet on the western slope of the Sangre de Cristo mountain range in Mora County. The river flows for through the eastern portion of that state and neighboring Texas before it...

 basin in eastern New Mexico and western Texas. It inhabits karst

KARST

Kilometer-square Area Radio Synthesis Telescope is a Chinese telescope project to which FAST is a forerunner. KARST is a set of large spherical reflectors on karst landforms, which are bowlshaped limestone sinkholes named after the Kras region in Slovenia and Northern Italy. It will consist of...

 topography, such as caves, caverns, and springs. It lives in mud and mats of saturated vegetation with small amounts of running water. The snail can be found at six sites: four in the Bitter Lake National Wildlife Refuge

Bitter Lake National Wildlife Refuge

Bitter Lake National Wildlife Refuge is a United States National Wildlife Refuge located in two separate sections in central Chaves County, New Mexico, USA, a few miles northeast of the city of Roswell. Both sections lie on the banks of the Pecos River...

 in New Mexico, one site at Diamond Y Spring and its drainage in Pecos County, Texas

Pecos County, Texas

Pecos County is a county located in Texas which is named for the Pecos River. It is one of the nine counties that comprise the Trans-Pecos region of West Texas. In 2000, its population was 16,809. The county seat is Fort Stockton....

, and one site at East Sandia Spring in Reeves County, Texas

Reeves County, Texas

Reeves County is a county located in the US state of Texas. It is one of the nine counties that comprise the Trans-Pecos region of West Texas. In 2000, its population was 13,137. Its seat is Pecos. Reeves County is named for George R. Reeves, a Texas state legislator and colonel in the...

.

Threats to this species and to other invertebrates living in the same habitat include the loss of the water sources that feed the karst cave network. This has been caused by the tapping of the aquifer

Aquifer

An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...

 beneath it; some areas have been drained dry. Diamond Y Spring and East Sandia Spring are in danger of being drained. The springs are also located in active oil and gas extraction regions, and pollution of the water is a threat. Fire is also a destructive force in the wildlife refuge habitat. The introduction

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

 of the decollate snail (Rumina decollata) is a potential threat, as it could be a predator upon the assiminea.