Occurs in large springs.

North America: San Marcos and Guadalupe River systems in Texas, USA.

endemic to a single state or province

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Historically occupied Comal (Guadalupe River system) and San Marcos springs, central Texas; widely introduced in springs in the Colorado and Rio Grande (including Pecos River) drainages in western Texas (Minckley et al. 1991, Page and Burr 1991).

Texas, U.S.A.

Maximum size: 44 mm TL

4.4 cm TL (male/unsexed; (Ref. 5723))

Length: 3 cm

benthopelagic; non-migratory; freshwater

Depth range based on 4 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 0.5 - 0.5
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Habitat Type: Freshwater

Comments: Cool, clear, high-volume discharge springs near emergence from underground limestone aquifers; often in swift water.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 6 - 20

Comments: Nine localities in western and central Texas were mapped by Lee et al. (1980). Formerly in two springs and spring runs; now in four more (C. Hubbs, pers. comm., 1995).

Live bearing. May breed year-round. Gravid females "dominate" populations from late March to early June in Devil's River.

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Occurs in springs in central Texas; introductions have improved the conservation status.

Not Evaluated

Comments: Likely secure, based on numbers and "wide" distribution (Minckley et al. 1991). No significant threats (C. Hubbs, pers. comm., 1995).

Comments: Subgenus ARTHROPHALLUS, SENILIS species group (Rauchenberger 1989). See Rauchenberger (1989) for a study of the interrelationships of the subgenera and species groups within the genus Gambusia.