Cycleptus sp.

Rio Grande blue sucker




Type Locality



Etymology/Derivation of Scientific Name

Cycleptus – round and slender; apparently meant to mean “small round mouth” by the author of the name, C.S. Rafinesque (Burr and Mayden 1999).



Cycleptus elongatus Koster 1957:39-40; Hubbs and Echelle 1972:150; Hubbs and Wauer (1973); Hubbs et al. (1977); Hubbs et al. 1991:24; Sublette et al. 1990: 10, 191, 215-217; Propst 1999:52-53.


Cycleptus sp. Hubbs et al. 2008:26.


Hubbs et al. (2008) refers to the Rio Grande, Texas, Cycleptus population as the Rio Grande blue sucker, Cycleptus sp. (formerly referred to as Cycleptus elongatus; Hubbs et al. 1991). Based on phylogenetic analyses, Bessert (2006) stated that Cycleptus in the Rio Grande basin is monophyletic and clearly divergent from C. elongatus. Buth and Mayden (2001) proposed that the Rio Grande drainage population to be recognized as a different species, noting that this population required further analysis of morphological and molecular variation and a formal description. According to Burr and Mayden (1999), Cycleptus samples from the Rio Grande were found to be divergent in a few characters compared to samples from other parts of the range; also preliminary studies (by Donald G. Buth and R.L. Mayden) of enzyme products revealed fixed differences in isozymes and allozymes in samples of Cycleptus from the Rio Grande mainstem when compared to samples from other parts of the range (samples from Texas coastal rivers not examined).



Maximum size: 568 mm SL (Burr and Mayden 1999).


Coloration: Body color of adults appears brassy or golden in overall color of body and fins. Some adults and larger juveniles have stripes (up to 12 on larger adults) on their side produced by dark pigment at the bases (scale pockets) of lateral scales (this feature is variable; Burr and Mayden 1999).


Teeth count:


Counts: 50+ lateral line scales; 22-30 dorsal fin rays (Hubbs et al. 1991, 2008). 56 (53-59) lateral line scales; 31 (29-35) dorsal fin rays (specimens from Rio Grande-Conchos drainage; Burr and Mayden 1999).


Body shape: Lip papillae long, extending forwards onto end of snout; eye closer to back of head than to tip of snout; head abruptly more slender than body, in adults; dorsal fin base more than one-third standard length (Hubbs et al. 2008).

Mouth position: Inferior (Sublette et al. 1990).


External morphology:


Distribution (Native and Introduced)

U.S. distribution: Rio Grande basin, in New Mexico, Texas, and Mexico (Hubbs and Echelle 1972; Bessert 2006). Lower Pecos River drainage, in New Mexico (Koster 1957; Sublette et al. 1990; Propst 1999).


Texas distribution: Found in the Rio Grande (Hubbs and Wauer 1973; Peden 1973; Hubbs et al. 2008).


Abundance/Conservation status (Federal, State, NGO)

Special Concern status, in Texas (Hubbs et al. 2008); Endangered status in New Mexico (Propst 1999).


Habitat Associations

Macrohabitat: According to Hubbs and Wauer (1973) young of year Cycleptus elongatus were seasonally abundant in Tornillo Creek, a small stream in Texas, taken between May and October (when Fundulus were scarce), where they probably migrate from the Rio Grande to the creek nursery area.


Mesohabitat: Collected from swift riffles in the lower Pecos River, New Mexico (Koster 1957). In the Black River (New Mexico), found only in deeper pools with silty bottoms (Cowley and Sublette 1987a).



Spawning season: In Texas, egg deposition probably in March or April, based on collection of 40 mm young taken in May and 20 mm young from the Rio Grande in April (Hubbs and Wauer 1973).


Spawning habitat:


Reproductive strategy:




Age at maturation:






Food habits: Cowley and Sublette (1987b) noted that fish in Black River, New Mexico have definite feeding preference for a firm substratum; diet items included Trichoptera (Hydropsyche sp., Cheumatopsyche sp., Ithytrichia sp.), Coleoptera, Odonata (Anisoptera, larval; Zygoptera, larval), Lepidoptera (Paragyractis sp.), Diptera [Ceratopogonidae, and Chironomidae (Dicrotendipes californicus, Cricotopus infuscatus, Paralauterborniella subcinta).


Growth and Population structure:



Phylogeny and morphologically similar fishes

Differences between C. elongatus and Cycleptus sp. include the following: in C. elongatus the lip papillae is short, only around the mouth, while in Cycleptus sp. the lip papillae is long, extending forwards onto end of snout; also, Cycleptus elongatus does not occur in the Rio Grande basin, while Cycleptus sp. is found only in the Rio Grande basin (Hubbs et al. 2008). Burr and Mayden (1999) indicated that Cycleptus sp. appear more golden or brassy in overall body color than Cycleptus elongatus (except during spawning season). In life, C. elongatus males are olive blue or slate olive on dorsum and sides of body with brassy reflections; venter bluish-white; lips white; all fins dark blue-gray, dusky, or black; coloration of female C. elongatus similar to the male, except during the breeding season when females may be tan to light blue (Burr and Mayden 1999). Adult and larger juvenile Cycleptus sp. sometimes have up to 12 (on largest adults) vague stripes on their side; Burr and Mayden (1999) found this variable feature in only the Colorado River drainage population of Cycleptus elongatus.


Host Records



Commercial or Environmental Importance

Gehlbach and Miller (1961) reported the recovery of Cycleptus (as C. elongatus) remains from Pueblo Indian ruins in Bandelier National Monument in the Rio Grande drainage of northern New Mexico.


[Additional literature noting collection of this species from Texas locations includes, but is not limited to the following: Hubbs (1957); Branson (1962).]



Bessert, M.L. 2006. Molecular systematics and population structure in the North American endemic fish genus Cycleptus (Teleostei: Catostomidae). Ph.D. dissertation, University of Nebraska, Lincoln. 219 pp.

Branson, B.A. 1962. Comparative cephalic and appendicular osteology of the fish family Catostomidae. Part I, Cycleptus elongatus (Lesueur). The Southwestern Naturalist 7(2):81-153.

Burr, B.M., and R.L. Mayden. 1999. A new species of Cycleptus (Cypriniformes: Catostomidae) from Gulf Slope drainages of Alabama, Mississippi, and Louisiana, with a review of the distribution, biology, and conservation status of the genus. Bulletin of the Alabama Museum of Natural History 20:19-57.

Buth, D.G., and Mayden, R.L. 2001. Allozymic and isozymic evidence for polytypy in the North American catostomid genus Cycleptus. Copeia 2001:899-906.

Cowley, D E. and J.E. Sublette. 1987a. Distribution of fishes in the Black River drainage, Eddy County, New Mexico. Southwestern Naturalist 32(2):213-221.

Cowley, D.E., and J.E. Sublette. 1987b. Food habits of Moxostoma congestum and Cycleptus elongatus (Catostomidae: Cypriniformes) in Black River, Eddy County, New Mexico. The Southwestern Naturalist 32(3):411-413.

Gehlbach, F.R., and R.R. Miller. 1961. Fishes from archaeological sites in northern New Mexico. The Southwestern Naturalist 6(1):2-8.

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

Hubbs, C. and A.A. Echelle. 1972. Endangered and non-game fishes of the upper Rio Grande basin. pp. 147-167 In: Symposium on Rare and Endangered Fishes of the Southwestern United States. New Mexico Dept. of Game and Fish., Santa Fe, New Mexico.

Hubbs, C., and R. Wauer. 1973. Seasonal changes in the fish fauna of Tornillo Creek, Brewster County, Texas. The Southwestern Naturalist 17(4):375-379.

Hubbs, C., R. J. Edwards, G. P. Garrett. 1991. An annotated checklist of the fishes of Texas, with keys to identification of species. Texas Journal of Science, Supplement 43(4):1-56.


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.


Hubbs, C., R.R. Miller, R.J. Edwards, K.W. Thompson, E.Marsh, G.P. Garrett, G.L. Powell, D.J. Morris, and R.W. Zerr. 1977. Fishes inhabiting the Rio Grande, Texas and Mexico, between El Paso and the Pecos confluence, pp. 91-97. In: Symposium on the importance, preservation and management of the riparian habitat, July 9, 1977, Tucson, Arizona.


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

Peden, A.E. 1973. Virtual extinction of Gambusia amistadensis n. sp., a Poeciliid fish from Texas. Copeia 1973(2):210-221.

Propst, D.L. 1999. Threatened and endangered fishes of New Mexico. Tech. Report No.1. New Mexico Dept. of Game and Fish., Sante Fe, NM. 84 pp.

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