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Goodenough Springs near the Rio Grande, Val Verde County, Texas (Peden 1973a).
Etymology/Derivation of Scientific Name
Maximum size: 54 mm TL (Page and Burr 1991).
Suborbital bar prominent; lateral stripe broad and conspicuous; dark markings on anus of mature females; caudal fin without prominent dark markings; markings on sides crescentric; dorsal and (in females) anal fins with yellow pigmentation (lost in preservation); predorsal stripe thin or absent; no dark bands on sides; median fins without large black spots near their bases (Hubbs et al. 2008).
Counts: Dorsal rays 7-8 (Hubbs et al. 2008).
Body shape: Slender; maximum body depth goes into standard length about 5 times in females; dorsal fin origin well behind anal fin origin (Hubbs et al. 2008).
External morphology: Longest serra goes 1.7 times (usually ranges from 1.5-1.9) onto width of segment on ray 4p of gonopodium; elbow of gonopodium composed of usually 2 (rarely 3) fused segments; tip of anterior branch of 4th ray of male gonopodium does not extend to tip of posterior branch; pectoral fin of males with slight indentation, shallower than widest pectoral fin ray; distal segments of anterior branch of 4th fin ray of gonopodium not coalesced to elbow; spines at tip of 3rd anal fin ray of male gonopodium 4-10 times longer than wide (Hubbs et al. 2008).
Internal morphology: Intestinal canal short with few convolutions (Hubbs et al. 2008).
Distribution (Native and Introduced)
Texas distribution: Original range included the headsprings and the 1.3 km springrun of Goodenough Springs (Val Verde County) to its confluence with the Rio Grande (Peden 1973a; Guillory 1980; Hubbs et al. 2008).
Abundance/Conservation status (Federal, State, NGO)
Extinct (Hubbs et al. 2008). Listed as Extinct by the American Fisheries Society; categories of threats: present or threatened destruction, modification, or reduction of habitat or range; other natural or anthropogenic factors that affect the existence of this species, including impacts of nonidigenous organisms, hybridization, competition, and/or predation; and a narrowly restricted range (Jelks et al. 2008). Species became extinct in the wild as a result of the inundation of Goodenough Springs (once the 3rd largest spring system in Texas) by Amistad Reservoir in 1968 (Peden 1973a; Guillory 1980; Hubbs et al. 2008). Culture populations existed until the late 1970s at the University of Texas at Austin and at the U.S. Fish and Wildlife Service endangered species culture facility in Dexter, New Mexico; these two populations eliminated prior to 1983 due to contamination by western mosquitofish (Gambusia affinis; Hubbs and Jensen 1984; Miller et al. 1989; Hubbs et al. 2008).
Macrohabitat: Prior to inundation, this species was common in the large, rapid flowing, warm springs (Guillory 1980).
Age at maturation:
Growth and Population structure:
Phylogeny and morphologically similar fishes
Gambusia amistadensis is a member of the G. nobilis species group, and is closely related to the Big Bend gambusia (G. gaigei; Guillory 1980).
Commercial or Environmental Importance
Guillory, V. 1980. Gambusia amistadensis (Peden), Goodenough gambusia. pp. 539 in D. S. Lee et al., Atlas of North American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, i-r+854 pp.
Hubbs, C., and B.L. Jensen. 1984. Extinction of Gambusia amistadensis, an endangered fish. Copeia 1984:529-530.
Hubbs, C., R.J. Edwards, and G.P. Garrett. 2008. An annotated checklist of the freshwater fishes of Texas, with keys to identification of species. Texas Journal of Science, Supplement, 2nd edition 43(4):1-87.
Jelks, H.L., S.J. Walsh, N.M. Burkhead, S. Contreras-Balderas, E. Diaz-Pardo, D.A. Hendrickson, J. Lyons, N.E. Mandrak, F. McCormick, J.S. Nelson, S.P. Platania, B.A. Porter, C.B. Renaud, J.J. Schmitter-Soto, E.B. Taylor, and M.L. Warren, Jr. 2008. Conservation status of imperiled North American freshwater and diadromous fishes. Fisheries 33(8):372-407.
Miller, R.R., J.D. Williams, and J.E. Williams. 1989. Extinctions of North American fishes during the past century. Fisheries 14(6):22-38.
Page, L. M., and B. M. Burr. 1991. A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston, Massachusetts. 432 pp.
Peden, A.E. 1973a. Virtual extinction of Gambusia amistadensis n. sp., a poecilid fish from Texas. Copeia 1973(2):210-221.
Peden, A.E. 1973b. Variation in anal spot expression of Gambusiin females and its effect on male courtship. Copeia 1973(2):250-263.