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Rio San Juan, in Nuevo Leon (Girard 1859).
Etymology/Derivation of Scientific Name
Rauchenberger (1989) recognized Gambusia speciosa as a distinct species.
Gambusia speciosa Girard 1859:121; Hubbs et al. 2008:39-40.
Gambusia affinis speciosa
Maximum size: Girard (1859) noted that the largest specimens examined measured 38.1 mm TL and were female.
Coloration: Girard (1859) described coloration: body is reddish brown, except belly which is yellowish or whitish; small black spots may be observed along the dorsal region near the base of the scales; dorsal and anal fins are grayish; caudal ventrals and pectorals are olivaceous.
Counts: Dorsal fin rays 7 (Hubbs et al. 2008).
Body shape: Dorsal fin origin well behind anal fin origin (Hubbs et al. 2008). Girard (1859) described the body as deep upon its middle and the tail tapering; head enters about four and one-half times in the total length; eye is proportionally large and circular, the diameter entering three times in the length of the side of the head; dorsal fin is very narrow and elevated; anal fin is narrow and deep; ventrals are small and pectorals are well developed.
External morphology: Distal end of the 4th fin ray of gonopodium in male curved in a wide arch; spines at tip of 3rd anal fin ray of male gonopodium (first enlarged ray) 1 to 3 times longer than wide (Hubbs et al. 2008).
Internal morphology: Intestinal canal short with few convolutions (Hubbs et al. 2008).
Distribution (Native and Introduced)
U.S. distribution: Primarily occurs in Mexico, found in streams and tributaries to the Rio Grande and more southern drainages (Hubbs et al. 2008).
Texas distribution: Occurs only in the Devils River and associated streams in Val Verde County (Hubbs et al. 2008).
Abundance/Conservation status (Federal, State, NGO)
Listed as Threatened by the American Fisheries Society; categories of threats: present or threatened destruction, modification, or reduction of habitat or range; and other natural or anthropogenic factors that affect the existence of this species, including impacts of nonidigenous organisms, hybridization, competition, and/or predation (Jelks et al. 2008). Stable in the lower Pecos River (Hoagstrom 2003). Over 3000 G. speciosa were taken in extensive collections from Pinto Creek (Texas) in June 2002 (Garrett and Edwards 2003). See also Contreras-Balderas (1974); Edwards et al. (2002), Edwards (2003) and Garrett et al. (2004).
Macrohabitat: Springs, outflows, marshes, stream margins (Minckley et al. 1991).
Age/size at maturation:
Growth and Population structure:
Food habits: Gambusia speciosa adults preyed on their young in experimental aquaria (Hubbs 1991).
Phylogeny and morphologically similar fishes
Gambusia speciosa is a member of the G. affinis species group (Rauchenberger 1989). Gambusia speciosa with 7 dorsal fin rays, and with the distal end of the 4th fin ray of gonopodium in male curved in a wide arch; while G. affinis (western mosquitofish) has 6 dorsal fin rays (rarely 7), and the distal end of the 4th fin ray of gonopodium in male parallel or curved only in a weak arch (Hubbs et al. 2008).
According to Garrett and Edwards (2003), G. clarkhubbsi (San Felipe gambusia) occurs in sympatry with G. speciosa in the headwaters of San Felipe Creek (Rio Grande tributary in Del Rio, Texas).
Commercial or Environmental Importance
Gambusia speciosa has been used successfully in experimental stream units and is known to have produced larvae in the streams (Matthews et al. 2006).
Contreras-Balderas, S. 1974. Speciation aspects and man-made community composition changes in Chihuahuan Desert fishes. In: Wauer, R.H., and D.H. Riskind (eds.). Transactions of the Symposium on the Biological Resources of the Chihuahuan Desert Region United States and Mexico. U.S. Department of the Interior, National Park Service Transactions and Proceedings Series (3):405-431.
Edwards, R.J. 2003. Ecological profiles for selected stream-dwelling Texas freshwater fishes IV. Report to the Texas Water Development Board. 19 pp.
Edwards, R.J., G.P. Garrett, and E. Marsh-Matthews. 2002. Conservation and status of the fish communities inhabiting the Conchos basin and middle Rio Grande, Mexico and U.S.A. Reviews in Fish Biology and Fisheries 12:119-132.
Garrett, G.P., and R.J. Edwards. 2003. New species of Gambusia (Cyprinodontiformes: Poeciliidae) from Del Rio, Texas. Copeia 2003(4):783-788.
Garrett, G.P., R.J. Edwards, and C. Hubbs. 2004. Discovery of a new population of Devils River minnow (Dionda diaboli), with implications for conservation of the species. The Southwestern Naturalist 49(4):435-441.
Girard, C.F. 1859. Ichthyological notices. Proceedings of the Academy of Natural Sciences of Philadelphia 11:113-122.
Hoagstrom, C.W. 2003. Historical and recent fish fauna of the lower Pecos River. pp 91-110 in: G.P. Garrett, and N.L. Allan (eds.) 33rd Annual Symposium of the Desert Fishes Council, Sul Ross University, Alpine, Texas. Vol. 42. Museum of Texas Tech University.
Hubbs, C. 1991. Intrageneric “cannibalism” in Gambusia. The Southwestern Naturalist 36(2):153-157.
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.
Matthews, W.J., K.B. Gido, G.P. Garrett, F.P. Gelwick, J.G. Stewart, and J. Schaefer. 2006. Modular experimental riffle-pool stream system. Transactions of the American Fisheries Society 135(6):1559-1566.
Minckley, W.L., G.K. Meffe, and D.L. Soltz. 1991. Conservation and management of short-lives fishes: the cyprinodontoids, Chapter 15. pp. 247-282 in: Minckley, W.L., and J.E. Deacon (Eds.). Battle Against Extinction: Native Fish Management in the American West. University of Arizona Press, Tucson, Arizona. 517 pp.
Rauchenberger, M. 1989. Systematics and biogeography of the genus Gambusia (Cyprinodontiformes: Poeciliidae). American Museum Novitates 2951:1-74.