Dionda episcopa

Roundnose Minnow

Type Locality

Headwaters of the Pecos River and Camanche Spring (tributary to Rio Grande), Texas (Girard 1857).

Etymology/Derivation of Scientific Name

Synonymy

      Dionda episcopa episcopa Girard; Knapp 1953:60.

Characters

Maximum size:  64 mm TL (Page and Burr 1991).

Coloration: Normal color pattern for species is reddish brown dorsally, silvery ventrally, with a dark lateral band and a caudal spot (Eddy and Underhill 1978; Hubbs and Brown 1956). Spawning fish take on a bright yellow-orange color, superimposed on normal color pattern; this bright coloration present on the proximal two-thirds of all the fins and forms a streak from the tip of the snout to the origin of the anal fin (Hubbs 1951; Wayne and Whiteside 1985). Wayne and Whiteside (1985) reported collection of larger males during the nonspawning period which were yellow in color; further, mature females collected during the spawning period had a slight yellow color, but were not as bright as males.

Teeth count: Pharyngeal teeth in main row typically 4-4; without prominent parallel grooves (Hubbs et al. 1991).

Counts: 8 anal fin rays; fewer than 45 lateral line scales; fewer than 10 soft rays on dorsal fin; dorsal and anal fins without spines (Hubbs et al. 1991).

Body shape:  Slender, fairly compressed (Knapp 1953; Page and Burr 1991); back slightly arched (Sublette et al. 1990); eye as long as snout (Hubbs et al. 1991).

Mouth position: Terminal; mouth small (Knapp 1953; Sublette et al. 1990).

External morphology: Caudal peduncle depth wide; long postorbital; predorsal scales not crowded; 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; no maxillary barbel present; 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; cartilaginous ridge of lower jaw hardly evident and not separated by a definite groove from the lower lip; distance from origin of anal fin to end of caudle peduncle contained two and one-half or fewer times in distance from tip of snout to origin of anal fin (Hubbs et al. 1991). Wayne and Whiteside (1985) collected breeding males with distinct tubercles present on the head, during the spawning season, and also reported that tubercles were present during other times of the year, but they were not so well developed; two larger females were observed to have a few small tubercles on the head.

Internal morphology: Intestinal canal long, more than twice the length of the body; intestine not wound spirally around the air bladder (Hubbs et al. 1991). Lining of body cavity jet black (Koster 1957).

Distribution (Native and Introduced)

U.S. distribution: Found in the middle and lower elevations of the Pecos Valley in New Mexico and northern Mexico (Lee and Gilbert 1980; Sublette et al. 1990).

Texas distribution: Inhabits the spring-influenced headwaters of Edwards Plateau streams of the Colorado, Guadalupe, and Pecos drainages (Hubbs et al. 1991). Hubbs (1957) stated that the species was essentially restricted to the Balconian and Chihuahuan regions (biotic provinces) of the state.

Abundance/Conservation status (Federal, State, NGO)

Locally common in Texas, rare elsewhere (Page and Burr 1991).

Habitat Associations

Macrohabitat: Primarily restricted to clear spring-fed waters that have slight temperature variations (Brown 1953; Hubbs 1951; Hubbs et al. 1953; Jurgens 1951; Kuehne 1955; Tilton 1961; Trevino 1955). Rocky pools, sometimes runs, of headwaters, creeks and small rivers (Page and Burr 1991). Dionda episcopa one of two species (endemic to the Edwards Plateau and Rio Grande drainage), that composed 49% of current fish assemblage in Independence Creek (Rio Grande drainage), TX (Bonner et al. 2005).

Mesohabitat: In Texas, species found to be a community dominant, as indicated by biomass, under both preflooding (normal) and postflooding (recovery) conditions (Harrell 1978). In New Mexico, species lives in shallow pools of low gradient rivers and streams with an abundance of aquatic vegetation (Koster 1957; Lee and Gilbert 1980; Sublette et al. 1990).

Biology

Spawning season: March – November in central Texas (Tilton 1961). In the Nueces River, Texas, two breeding populations observed in April; spawning when water temperatures reach about 17-18 degrees C (Hubbs 1951). Summer, in New Mexico (Koster 1957). A study at Fessenden Spring, Texas, indicated some spawning from January – August with spawning peaks occurring in April and May and in July and August (Wayne and Whiteside 1985).

Spawning habitat: In the Nueces River, Texas, fish observed in water temperature 17-18 degrees C, buried over 2.5 cm in gravel, as far as 0.3 m from bank; 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 2.5 cm water at another locality in the Nueces River (Hubbs 1951). In New Mexico, fish spawned over gravel in spring-fed streams (Koster 1957).

Spawning behavior:

Fecundity: Eggs heavy and non-adhesive (Hubbs 1951). Based on 50 females containing mature ova collected from Fessenden Spring, Texas, fecundity ranged from 2 – 540 with a mean of 164 ova (Wayne and Whiteside 1985).

Age at maturation: 

Migration: 

Growth and Population Structure: 80 males and 98 females were collected from Fessenden Spring, Texas, with a 0.82:1.00 female to male ratio (Wayne and Whiteside 1985).

Longevity:

Food habits:  Herbivorous (Hlohowskyj et al. 1989; Sublette et al. 1990); feeding mainly on algae and other vegetation (Koster 1957; Lee and Gilbert 1980; Page and Burr 1991); plant material in gut tends to make belly look dark and discolored (Page and Burr 1991).

Phylogeny and morphologically similar fishes

Species similar to the Devils River minnow (Dionda diaboli), but D. diaboli has black wedge on caudal fin base, larger eye, dark edged scales on back and upper side, orange fins (Page and Burr 1991).

Host Records

Trematoda: Plagioporus sinitsini, Posthodiplostomum minimum (Mathis 1993; Mayberry et al. 2000).

Commercial or Environmental Importance

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

[Additional literature noting collection of this species from Texas locations includes, but is not limited to the following: Wayne (1979); Klaus (1991); Pecos River (Rhodes and Hubbs 1992).]

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.

Brown, W.H. 1953. Introduced fish species of the Guadalupe River Basin. Texas Journal of Science 5:245-251.

Eddy, S., and J.C. Underhill. 1974. Northern Fishes. University of Minnesota Press. 414 pp.

Girard, C. 1857. 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. 1856 (8):165-213.

Harrell, H.L. 1978. Response of the Devil’s River (Texas) fish community to flooding. Copeia 1978(1):60-68.

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. 1951. Observations on the breeding of Dionda episcopa serena in the Nueces River, Texas. Texas Journal of Science 3:490-492.

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.

Hubbs, C., R.A. Kuehne, and J.C. Ball. 1953. The fishes of the upper Guadalupe River, Texas. Texas J. Sci. 5:216-244.

Jurgens, K.C. 1951. The distribution and ecology of the fishes of the San Marcos River. M.A. Thesis, University of Texas, Austin.

Klaus, B. 1991. A survey of the endoparasitic helminthes of Dionda episcopa, the roundnose minnow, and Astyanax mexicanus, the Mexican tetra, from the San Marcos and Comal Rivers, Texas. M.A. Thesis, Southwest Texas State University, San Marcos.

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.

Kuehne, R.A. 1955. Stream surveys of the Guadalupe and San Antonio Rivers. Texas Game and Fish Com., IF Report Ser. 1:1-56.

Lee, D. S. 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.

Mathis, S.D. 1993. A morphometric study of Plagioporus sinitsini Mueller (Digenea: Opecoelidae) from the gallbladder of three Cyprinid hosts from the Blanco, San Marcos, and Comal Rivers in central Texas. Master of Science Thesis, Southwest Texas State University, San Marcos. 44 pp.

Mayberry, L.F., A.G. Canaris, J.R. Bristol, and Scott L. Gardner. 2000. Bibliography of parasites and vertebrate host in Arizona, New Mexico and Texas (1893-1984). University of Nebraska Harold W. Manter Laboratory of Parasitology Web Server, published on the World-Wide-Web, 100 pp.

Page, L.M., and B.M. Burr. 1991. A Field Guide to Freshwater Fishes: North America, north of Mexico. Houghton Mifflin Company, Boston, Massachusetts. 432 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.

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

Tilton, J.E. 1961. Ichthyological survey of the Colorado River of Texas. M.A. Thesis, University of Texas, Austin.

Trevino, D.B. 1955. The ichthyofauna of the lower Rio Grande River, from the mouth of the Pecos to the Gulf of Mexico. M.A. Thesis, University of Texas, Austin.

Wayne, L.M. 1979. Ecology of the roundnose minnow, Dionda episcopa (Osteichthyes: Cyprinidae) from three central Texas springs. M.S. Thesis, Southwest Texas State University, San Marcos. 50 pp.

Wayne, L.M., and B.G. Whiteside. 1985. Reproduction data on Dionda episcopa from Fessenden Spring, Texas. Texas Journal of Science 37(4):321-328.