Picture by Chad Thomas, Texas State Universtiy-San Marcos

Dionda episcopa

roundnose minnow

Type Locality

Headwaters of the Pecos River and Camanche Spring (tributary to Rio Grande), Texas (Girard 1856).

Etymology/Derivation of Scientific Name

Dionda – from the Greek Dione, the mother of Venus (Edwards 1999); episcopa – bishop or pope, alluding to John Pope, who led party that collected type (Scharpf 2005).

Synonymy

Dionda episcopa Girard 1856:14; Lee and Gilbert 1980:154; Hubbs et al. 1991:18; Schonhuth et al. (2008).

Dionda episcopa episcopa Knapp 1953:60.

Characters

Maximum size: 76 mm (3.00 in) SL (Thomas et al. 2007).

Coloration: A black band through eye to snout, may not be notable (Hubbs et al. 1991); rounded caudal spot (Hubbs and Brown 1956). Girard (1856) described coloration of individuals from the Pecos River and Camanche Spring: dorsal region blackish brown; a black vitta is observed along the sides, just above the lateral line, extending from a black spot, upon the base of the caudal, to the extremity of the snout. The inferior region is yellowish white spread over with minute black dots.

Pharyngeal teeth count: 0,4-4,0 (Hubbs et al. 1991; Schonhuth et al. 2008).

Counts: 8 anal fin soft rays; fewer than 10 soft rays on dorsal fin (Hubbs et al. 1991); 36-41 lateral line scales (Edwards 1999).

Mouth position: Subterminal (Schonhuth et al. 2008) or terminal (Sublette et al. 1990).

Body shape:  Slender and fusiform in profile and compressed, with the back slightly arched; head large, forming about a fifth of the length; eye large and subcircular, its diameter contained three and one-half times in the length of the side of the head; insertion of pelvic fins is situated a little posterior to the anterior margin of the dorsal fin (Girard 1856).

Morphology: First obvious dorsal fin ray a thin splint, closely attached to the following well developed but unbranched ray; lower lip thin, without a fleshy lobe; lateral line usually not decurved, either straight or with broad arch; premaxillaries protractile; upper lip separated from skin of snout by a deep groove continuous across the midline (Hubbs et al. 1991); fins moderately developed; scales large; lateral line following the middle of the flanks (Girard 1856). Nuptial tubercles present on head (Schonhuth et al. 2008).  Intestine long, more than twice the length of the body (Hubbs et al. 1991). Lining of body cavity black (Koster 1957).

Distribution (Native and Introduced)

U.S. distribution: Pecos River; tributaries to Rio Bravo near Big Bend National Park (Texas; Coahuila, Mexico; Scharpf 2005). Found in the middle and lower elevations of the Pecos Valley in New Mexico (Sublette et al. 1990).

Texas distribution: Pecos River (Scharpf 2005; Schonhuth et al. 2008). Schonhuth et al. (2008) reported collection of this species from Limpia Creek at Ford Davis, Jeff Davis Co., Pecos River (Rio Grande Drainage, Texas).

[Additional literature noting collection of this species from Texas locations includes, but is not limited to the following: Hubbs (1957); Pecos River (Rhodes and Hubbs 1992).]

Abundance/Conservation status (Federal, State, Non-governmental organizations)

Common (US); critically imperiled, endangered (Mexico; Scharpf 2005). Dionda episcopa (endemic to the Edwards Plateau and Rio Grande drainage), composed 30% of current fish assemblage in Independence Creek (tributary of the lower Pecos River), Rio Grande drainage, Texas (Bonner et al. 2005). Koster (1957) reported D. episcopa as one of the most abundant species in the lower Pecos River of New Mexico. According to Cowley and Sublette (1987), this species restricted to headwater spring systems from Santa Rosa to the Carlsbad area such as those in the Black River drainage, and designated as “threatened” (State Endangered, Group II) species in New Mexico; D. episcopa removed from this list in 1983 (Sublette et al. 1990).

Habitat Associations

Macrohabitat: Spring-influenced headwater streams (Hubbs et al. 1991).

Mesohabitat: Hubbs and Brown (1956) reported that the species is restricted to clear, spring-fed waters having little temperature variation.

Biology

Spawning season: In New Mexico, species spawns in the summer (Koster 1957).

Spawning habitat: In New Mexico, fish spawned over gravel in spring-fed streams (Koster 1957).

Spawning behavior: No information at this time.

Fecundity: No information at this time.

Age/size 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: Herbivorous (Hlohowskyj et al. 1989; Sublette et al. 1990); vegetation comprises the bulk of diet (Koster 1957).

Phylogeny and morphologically similar fishes

Dionda episcopa is apparently an ecological equivalent of the Guadalupe roundnose minnow (D. nigrotaeniata), which is endemic to the spring-fed headwaters of the Guadalupe and Colorado River basins; the two may be closely related (Edwards et al. 2004). D. episcopa is very similar to the Manantial roundnose minnow (D. argentosa) and the Devils River minnow (D. diaboli), but D. episcopa is restricted to streams in which the latter two species are not found (Edwards 1999). D. episcopa adults are much longer and stouter than those of D. diaboli; the former species has 36-41 lateral line scales versus 32-36 in D. diaboli; D. episcopa lacks cross-hatched scales and double dashes along the lateral line, while these are characteristic of D. diaboli (Edwards 1999). D. episcopa differs also from the Nueces roundnose minnow (D. serena; of the Nueces River drainage) in that it lacks cross-hatched scale markings and double dashes along the lateral line and D. episcopa is not found in the Nueces River drainage (Edwards 1999).

Host Records

 No information at this time. 

Commercial or Environmental Importance

Important bait fish of the lower Pecos Valley, New Mexico (Koster 1957).

References

Bonner, T.H., C. Thomas, C.S. Williams, and J.P. Karges. 2005. Temporal assessment of a west Texas stream fish assemblage. The Southwestern Naturalist 50(1):74-106.

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.

Eschmeyer, W. N. Catalog of Fishes electronic version (23 April 2008): http://www.calacademy.org/research/ichthyology/catalog/fishcatsearch.html

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.

Hlohowskyj, C.P., M.M. Coburn, and T.M. Cavender. 1989. Comparison of a pharyngeal filtering apparatus in seven species of the herbivorous cyprinid genus, Hybognathus (Pisces: Cyprinidae). Copeia 1989(1):172-183.

Hubbs, C. 1957. Distributional patterns of Texas fresh-water fishes. The Southwestern Naturalist 2(2/3):89-104.

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.

Knapp, F.T. 1953. Fishes found in the freshwater of Texas. Ragland Studio and Litho Printing Co., Brunswick. 166 pp.

Koster, W.J. 1957. Guide to the fishes of New Mexico. Univ. New Mexico Press, Albuquerque. 116 pp.

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.

Rhodes, K., and C. Hubbs. 1992. Recovery of Pecos River fishes from a red tide fish kill. The Southwestern Naturalist 37(2):178-187.

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.

Sublette, J.E., M.D. Hatch, and M. Sublette. 1990. The Fishes of New Mexico. University of New Mexico Press, Albuquerque. 393 pp.

Thomas, C., T.H. Bonner, B.G. Whiteside. 2007. Freshwater Fishes of Texas. Texas A&M Press, College Station. 202 pp.