Picture by Chad Thomas, Texas State University-San Marcos
Nueces roundnose minnow
Rio Sabinal, Texas and Rio Nueces, Texas (Girard 1856).
Etymology/Derivation of Scientific Name
Dionda – from the Greek Dione, the mother of Venus (Edwards 1999); serena – fair, possibly referring to fairer complexion when compared to the roundnose minnow (Dionda episcopa; Scharpf 2005).
Dionda serena Girard 1856:177.
Dionda texensis Girard 1856:177.
Dionda episcopa Hubbs (1951); Hubbs and Brown (1956); Lee and Gilbert 1980:154.
Dionda serena Hubbs et al. 1991:18; Mayden et al. (1992); Gilbert 1998:147; Nelson et al. 2004:70, 198.
Maximum size: 76 mm (3.00 in) SL (Thomas et al. 2007).
Coloration: Cross-hatched scale markings and double dashes long the lateral line; rounded caudal spot (Hubbs and Brown 1956; Edwards 1999). Black band through eye to snout (Hubbs et al. 1991). Describing coloration of individuals from the Nueces River, Girard (1956) recorded the dorsal region as grayish brown; the abdominal region grayish white; a diffused grayish black band may be observed along the middle of the flanks, embracing the lateral line beneath, and a black spot upon the base of the caudal; ventral and pectoral fins yellowish. Coloration of Sabinal River specimens was described by Girard (1856): light brown dorsal region, the flanks and abdomen silvery, the lateral line scales dotted with black, imitating spots; a black spot upon base of the caudal fin.
Counts: Pharyngeal teeth 0,4-4,0; 34-40 lateral line scales; 7 anal fin soft rays (Hubbs and Brown 1956; Hubbs et al. 1991).
Mouth position: Subterminal
Body shape: Slender (Schonhuth et al. 2008). Distance from origin of anal fin to end of caudal peduncle contained two and one-half or fewer times in distance from tip of snout to origin of anal fin (Hubbs et al. 1991). Girard (1856) described individuals from the Nueces River: body deep upon the middle; head small and subconical, entering five and one-half times the total length; eye large and circular; insertion of ventral fin placed slightly posteriorly to the anterior margin of the dorsal. Specimens from the Sabinal River were described by Girard (1856) as slender and elongated, the dorsal outline being nearly straight; the head enters five and one-half times in the total length; eye large and circular, the diameter entering only three times in the length of the side of head; insertion of pelvic fins immediately opposite the anterior margin of the dorsal fin.
Morphology: 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 skin of snout by a deep groove continuous across the midline (Hubbs et al. 1991). Girard (1856) noted a somewhat depressed lateral line, in Nueces River specimens. Intestine 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: Endemic to the Nueces River drainage unit (Hubbs et al. 1991; Warren et al. 2000; Edwards et al.
Abundance/Conservation status (Federal, State, Non-governmental organizations)
Scharpf (2005) listed Dionda serena as imperiled. However, Edwards et al. (2004) reported that the species was not federally protected and noted that it is abundant throughout its limited distribution though its status could easily change due to reductions in water quality and/or quantity. Warren et al. (2000) listed status as currently secure.
Macrohabitat: Spring-fed headwaters (Hubbs et al. 1991; Edwards 1999; Edwards et al. 2004).
Mesohabitat: Hubbs and Brown (1956) reported that the species is restricted to clear, spring-fed waters having little temperature variation.
Spawning season: In the Nueces River, Texas, two breeding populations observed in April; spawning when water temperatures reach about 17-18°C (62.6-64.4°F) (Hubbs 1951; Lee and Gilbert 1980).
Spawning Habitat: In the Nueces River, Texas, fish observed in water temperature 17-18°C (62.6-64.4°F), buried over 25 mm (0.98 in) in gravel; gravel substrate was filled with ground water; fish became active when disturbed, but soon returned to same spot and resumed spawning. Fish observed spawning in 25 mm (0.98 in) of water at another locality in the Nueces River (Hubbs 1951; Lee and Gilbert 1980).
Spawning Behavior: No information at this time.
Fecundity: Eggs heavy and non-adhesive (Hubbs 1951; Lee and Gilbert 1980).
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
Dionda serena is thought to be an ecological equivalent of the Devils River minnow (D. diaboli), a species found in the Rio Grande drainage; the two may be closely related (Hubbs and Brown 1956; Edwards et al. 2004). D. serena does have cross-hatched scale markings, but they are not as distinct as those in D. diaboli; both D. serena and D. diaboli have double dashes along the lateral line; D. serena has 7 dorsal fin soft rays and 34-40 lateral line scales, while D. diaboli has 8 dorsal fin soft rays and 32-36 lateral line scales (Edwards 1999). Neither the roundnose minnow (D. episcopa; found in the Pecos River in Texas), nor the manantial roundnose minnow (D. argentosa; found in the Devils River, Sycamore Creek and San Felipe Creek of the Rio Grande drainage, Texas) have the cross-hatched scale markings or double dashes along the lateral line that are found in D. serena; both D. episcopa and D. argentosa have lateral line counts of 36-41, while D. serena has 34-40 lateral line scales (Edwards 1999). The Guadalupe roundnose minnow (D. nigrotaeniata) is found only in the Colorado and Guadalupe River basins, Texas.
No information at this time.
Commercial or Environmental Importance
No information at this time.
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., 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.
Gilbert, C.R. 1998. Type catalogue of recent and fossil North American freshwater fishes: families Cyprinidae, Catostomidae, Ictaluridae, Centrarchidae and Ellasomatidae. Florida Museum of Natural History, Special Publication 1, University of Florida, Gainesville.
Girard, C. 1856. Researches upon the cyprinid fishes inhabiting the fresh waters of the United States of America west of the Mississippi Valley, from specimens in the museum of the Smithson. Institution. Proc. Acad. Nat. Sci. Phila. (8):165-213.
Hubbs, C. 1951. Observations on the breeding of Dionda episcopa serena in the Nueces River, Texas. Texas Journal of Science 3:490-492.
Hubbs, C., and W.H. Brown. 1956. Dionda diaboli (Cyprinidae), a new minnow from Texas. Southwestern Naturalist 1:69-77.
Hubbs, C., R. J. Edwards, and G. P. Garrett. 1991. An annotated checklist of the freshwater fishes of Texas, with keys to the identification of species. Texas Journal of Science, Supplement 43(4):1-56.
Lee, D.S., and C.R. Gilbert. 1980. Dionda episcopa (Girard), Roundnose minnow. pp. 154 in D. S. Lee et al., Atlas of North American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, i-r+854 pp.
Mayden, R.L., Matson, R.H., Hillis, D.M., 1992. Speciation in the North American Genus Dionda (Teleostei: Cypriniformes). In: Mayden, R.L. (Ed.), Systematics, Historical Ecology and North American Freshwater Fishes. Standford University Press, California, pp. 710–746.
Nelson, J.S., E.J. Crossman, H. Espinoza-Perez, L.T. Findley, C.R. Gilbert, R.N. Lea, and J.D. Williams. 2004. Common and Scientific Names of Fishes from the United States, Canada, and Mexico. American Fisheries Society, Special Publication 29, Bethesda, Maryland.
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.
Thomas, C., T.H. Bonner, B.G. Whiteside. 2007. Freshwater Fishes of Texas. Texas A&M Press, College Station. 202 pp.
Warren, M.L., Jr., B.M. Burr, S.J. Walsh, H.L. Bart, Jr., R.C. Cashner, D.A. Etnier, B.J. Freeman, B.R. Kuhajda, R.L. Mayden, H.W. Robison, S.T. Ross, and W.C. Starnes. 2000. Diversity, Distribution, and Conservation status of the native freshwater fishes of the southern United States. Fisheries, Conservation. 25(10):7-29.