Species Information

Kingdom: Animalia
  Phylum: Arthropoda
    Class: Malacostraca
      Order: Isopoda
        Family: Sphaeromatidae
          Genus: Thermosphaeroma
            Species: thermophilum

Socorro Isopod - Thermosphaeroma thermophilum

Socorro Isopod

Image courtesy of Biota Information System of New Mexico

272254

Species Extent (New Mexico)

General Description

Socorro Isopod (Thermosphaeroma thermophilum) is an approximately 1 cm isopod that is only found in Sedillo Spring in Socorro County, New Mexico. They inhabit thermal spring waters with temperatures ranging from 25-33?C. They walk along the bottom of pools and runs and filter feed.

Status

Global Rank: G1

State Rank: S1

Rank Metadata
State Rank: S1 Rank Changed: 08/04/2025
Rank Reviewed: 05/01/1982
Reason: The Socorro Isopod is a freshwater species endemic to a single thermal spring system near the City of Socorro, in New Mexico, U.S.A. The natural habitat at Sedillo Spring was destroyed sometime in the early 1900s, though the species can still be found in a heavily modified environment at the outflow of the thermal spring. In 1988, outflow from the spring diminished and the habitat dried out, leading to the apparent extirpation of the species at Sedillo Spring. Captive bred individuals were reintroduced to the site a month later, when flows returned. Therefore, the species was assessed as Extinct in the Wild in 1996. Currently, the isopod has an extent of occurrence (EOO) and area of occupancy (AOO) of just 1 km<sup>2</sup>, as it is known from just one site. This site is considered one occurrence, as the main threat to the species is diminished spring flows. Continuing decline in area, extent, and quality of habitat has been observed, and the site requires annual maintenance. Therefore, the species is currently assesed as S1 in New Mexico.
 
Ecological Factors
Specificity: Very narrow. Specialist or community with key requirements scarce. Range Extent: <100 square km (less than about 40 square miles)
Occurences: 1 - 5 Population Size: Unknown
Area of Occupancy: The Socorro Isopod is known only from the thermal outflow of Sedillo Spring, located approximately 3 km west of the City of Socorro, in Socorro County, New Mexico. The spring habitat was altered in the early 1900s to support a bathhouse, referred to as "The Evergreen", which was subsequently abandoned (Shuster 1981a). The water system is now a small, cement lined animal watering tank, a smaller pool, and about 40 meters of open irrigation pipe (USFWS 1982). In total, the Isopod occurs throughout the entire 50 m reach of the spring system (Lang <em>et al</em>. 2006). In August of 1988, this altered native habitat dried up when spring discharge was diminished, leading to a likely extinction event of the Socorro Isopod in the wild. T Threat Summary: N/A

State Status: E

Federal Status: Listed Endangered [LE]

USFS Status:

BLM Status:

SWAP Status: SGCN

NMRP Strategy Status:

Observations in Natural Heritage New Mexico Database

Number of Subpopulations: 3

Number of Mapped Locations: 5

Number of Observations: 68

Observation date range: 01-01-1898 to 12-27-2022


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