Picture by Chad Thomas, Texas State Universtiy-San Marcos
manantial roundnose minnow
San Felipe Creek and Devils River (tributaries of the Rio Grande del Norte; Girard 1856).
Etymology/Derivation of Scientific Name
Dionda – from the Greek Dione, the mother of Venus (Edwards 1999); argentosa – silvery, referring to the sides and abdomen (Scharpf 2005). Common name of this species “manantial” is a Spanish word that translates as “spring-run”, referring to the habitat necessary for survival of this species (Hubbs et al. 1991).
Dionda argentosa Girard 1856:178; Hubbs et al. 1991:18; Gold et al. (1992); Mayden et al. (1992).
Dionda episcopa Hubbs and Brown (1956); Robinson (1959).
Maximum size: 75.9 mm SL (3.13 in) (Cantu and Winemiller 1997).
Coloration: A black band through eye to snout; small black caudal spot (Hubbs and Brown 1956; Hubbs et al. 1991). Gilbert (1856) described coloration of the dorsal region as reddish brown; sides and abdomen silver; fins olivaceous.
Counts: Pharyngeal teeth 0,4-4,0; 8 anal fin soft rays; 36-41 lateral line scales; fewer than 10 dorsal fin soft rays (Hubbs and Brown 1956; Edwards 1999; Hubbs et al. 1991).
Mouth postion: Subterminal (Schonhuth et al. 2008).
Body shape: Terete.
Morphology: Caudal spot rounded; first obvious dorsal fin ray a thin splint, closely attached to the following well developed but unbranched ray, especially at tip; lower lip thin, without a fleshy lobe; lateral line usually not decurved, either straight or with a broad arch; premaxillaries protractile; upper lip separated from the skin of snout by a deep groove continuous across the midline. Intestinal canal long, more than twice the length of the body (Hubbs et al. 1991).
Distribution (Native and Introduced)
U.S. distribution: Found only in Texas.
Texas distribution: Devils River, San Felipe and Sycamore creeks in Val Verde County (Hubbs et al. 1991; Garrett et al. 1992). Schonhuth et al. (2008) reported collection of this species from the lower Pecos River at Pandale, Val Verde Co. and from San Felipe Spring, in Moore Park, Val Verde County.
Abundance/Conservation status (Federal, State, Non-governmental organizations)
D. argentosa is abundant in the Devils River, San Felipe Creek, and Sycamore Creek and is not federally protected (Cantu and Winemiller 1997; Garrett et al. 1992; Edwards et al. 2004). However, Edwards et al. (2004) stated that reductions in water quality and/or quality could easily alter their status. Scharpf (2005) listed the species as imperiled.
Macrohabitat: Headwaters and runs of spring-influenced waters (Hubbs and Brown 1956; Hubbs and Garrett 1990; Hubbs et al. 1991).
Mesohabitat: Adapted to flood-prone environment (Harrell 1978); D. argentosa primarily occupied riffles prior to flooding in the Devils River, but shifted toward channel habitat post-flooding. Cantu and Winemiller (1997) reported that D. argentosa occurred in most mesohabitats of the Devils River, but was not found in isolated pools or a deep pool site which may indicate avoidance of large predators. Hubbs and Brown (1956) reported that the species is restricted to clear, spring-fed waters having little temperature variation.
Spawning season: Collection of small individuals (< 15 mm, 0.60 in, SL) from fall – spring, with highest incidence in winter, suggests that reproduction may peak during the fall in the Devils River, Texas (Cantu and Winemiller 1997).
Spawning habitat: No information at this time.
Spawning Behavior: No information at this time.
Fecundity: No information at this time.
Age at maturation: No information at this time.
Migration: No information at this time.
Growth and Population structure: No information at this time.
Longevity: No information at this time.
Food habits: No information at this time.
Phylogeny and morphologically similar fishes
D. argentosa and the Devils River minnow (D. diaboli) are sympatric species in the Devils River, Sycamore Creek and San Felipe Creek, Texas: adults of D. argentosa are much longer and stouter than those of D. diaboli; D. argentosa has 36-41 lateral line scales versus 32-36 in D. diaboli; and D. argentosa lacks the cross-hatched scales and double dashes along the lateral line which are characteristic of D. diaboli (Edwards 1999); the caudal spot is rounded in D. argentosa and is wedge-shaped in D. diaboli (Hubbs et al. 1991). Dionda argentosa and the roundnose minnow (D. episcopa) are very similar, but the latter species is restricted to streams in the Pecos River were D. argentosa is not found (Edwards 1999). The Nueces roundnose minnow (D. serena) occurs only in the Nueces River system and has 7 anal fin rays versus 8 anal fin rays in D. argentosa (Edwards 1999). The Guadalupe roundnose minnow (D. nigrotaeniata) is found only in the Colorado and Guadalupe river basins (Edwards et al. 2004).
No information at this time.
Commercial or Environmental Importance
D. argentosa is a sympatric congener of the Devils River minnow (D. diaboli; Garrett et al. 1992), and as such its status may be aided by current efforts to recover D. diaboli (Edwards et al. 2004).
The D. argentosa and D. diaboli sympatric species pair apparently evolved allopatrically and their current sympatry resulted from the often complex paleohydrology of the region (Hubbs and Miller 1977; Mayden et al. 1992; Edwards 1999; Edwards 2001).
Cantu, N.E.V., and K.O. Winemiller. 1997. Structure and habitat associations of Devils River fish assemblages. Southwestern Naturalist 42(3):265-278.
Edwards, R.J. 1999. Ecological profiles for selected stream-dwelling Texas freshwater fishes II. Report to the Texas Water Development Board. 69 pp.
Edwards, R.J. 2001. Ecological Profiles for selected stream-dwelling Texas freshwater fishes III. Report to the Texas Water Development Board. 59 pp.
Edwards, R.J., G.P. Garrett, and N.L. Allan. 2004. Aquifer-dependent fishes of the Edwards Plateau region. Chapter 13, pp. 253-268 in: Mace, R.E., E.S. Angle, and W.F. Mullican, III (eds.). Aquifers of the Edwards Plateau. Texas Water Development Board. 360 pp.
Garrett, G.P., R.J. Edwards, and A.H. Price. 1992. Distribution and status of the Devils River minnow, Dionda diaboli. The Southwestern Naturalist 37(3):259-267.
Girard, C.F. 1856. Researches upon the Cyprinoid fishes inhabiting the fresh waters of the United States of America, west of the Mississippi Valley, from specimens in the Museum of the Smithsonian Institution. Proceedings of the Academy of Natural Sciences of Philadelphia 8(5):165-213.
Gold, J.R., Y. Li, M. C. Birkner, and J.D. Jenkin. 1992. Chromosomal nor karyotypes and genome sizes in Dionda (Osteichthyes: Cyprinidae) from Texas and New Mexico. The Southwestern Naturalist 37(3): 217-222.
Harrell, H.L. 1978. Response of the Devil’s River (Texas) fish community to flooding. Copeia 1978(1):60-68.
Hubbs, C., and G.P. Garrett. 1990. Reestablishment of Cyprinodon eximius (Cyprinodontidae) and status of Dionda diaboli (Cyprinidae) in the vicinity of Dolan Creek, Val Verde Co., Texas. The Southwestern Naturalist 35(4):446-448.
Hubbs, C. and W.H. Brown. 1956. Dionda diaboli (Cyprinidae), a new minnow from Texas." The Southwestern Naturalist 1(2): 69-77.
Hubbs, C.L., and R.R. Miller. 1977. Six distinctive cyprinid fish species referred to Dionda inhabiting segments of the Tampico Embayment drainage of Mexico. Trans. San Diego Soc. Nat. Hist. 18(17):265-335.
Mayden, R.L., R.M. Matson, and D.M. Hillis. 1992. Speciation in the North American genus Dionda (Teleostei: Cypriniformes). Pp. 710-746 In: Mayden, R.L. (ed.), Systematics, Historical Ecology, and North American freshwater fishes. Stanford Univ. Press, Palo Alto, California. 969 pp.
Robinson, D.T. 1959. The Ichthyofauna of the lower Rio Grande, Texas and Mexico. Copeia 1959(3):253-256.
Scharpf, C. 2005. Annotated checklist of North American freshwater fishes, including subspecies and undescribed forms, Part 1: Petromyzontidae through Cyprinidae. American Currents, Special Publication 31(4):1-44.
Schonhuth, S., I. Doadrio, O. Dominguez-Donminguez, D.M. Hillis, and R.L. Mayden. 2008. Molecular evolution of southern North American cyprinidae (Actinopterygii), with the description of the new genus Tampichthys from central Mexico. Molecular Phylogenetics and Evolution 47(2008):729-756.