9550

• UCREFRP Catalog Number: 9550
• Author: Snyder, D. E. and R. T. Muth.
• Title: Catostomid Fish Larvae and Early Juveniles of the Upper Colorado River Basin - Morphological Descriptions, Comparisons, and Computer-interactive Key.
• USFW Year: 2004.
• USFW - Doc Type: Fort Collins, CO.
• Copyright Material: NO

Species Account - Catostomus ardens

Fig. 7. Catostomus ardens adult (@Joseph R. Tomelleri).

Adult Description: Back without conspicuous predorsal
keel. Caudal peduncle deep, about 8-10% of body length.
Mouth inferior but well forward. Lips relatively small with
papillae, without notches at outer corners; lower lip with
deep medial cleft, lobes usually adjacent and not reaching
a perpendicular from nostrils. No prominent cartilaginous
ridge on anterior margin of lower jaw. Nodules of gill
rakers slightly to un-branched. Scales relatively large.
Dorsal fin membranes well pigmented. Fontanelle wide.
Total length usually 25-35 cm, up to 65 cm. (Also, Table I.)

Reproduction: Non-guarding, open-substrate lithophil.
Spring, usually late May to mid June, ;, 18 oc. Tributary
streams, inlets, or rocky shoals near shore of lakes; some-
times over sand or gravel in water <60 cm deep. Observed
in spawning aggregations of 400-500. Water-hardened
eggs 2.9-3.2 mm diameter, demersal, initially adhesive.

Young: Hatch in 8-9 days at I rc. Swim-up 7-8 days
after hatching. Young mostly in spawning streams or near
shore in shallow water. Observed to graze on filamentous
algae or algae on fixed objects.

r
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NEW M"i;;;;;'

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i "

Fig. 8. Recent distribution of Catostomus ardens in
Colorado River Basin.

Table 1. Selected juvenile and adult meristics for Catostomus ardens. P = principal rays; R = rudimentary rays; D = dorsal;
V = ventral. Scales are lateral series or line when complete. Four added to vertebral count for Weberian complex. Gill rakers
for exterior row of first arch, specimens >70 mm SL. Mean or modal values underlined if known and noteworthy; rare or
questionable extremes in parentheses.

Character Original Literature Character Original
Dorsal Fin Rays - P: (10)11-12-13(14) 11-13 Dorsal Fin Rays - R: 2-5
Anal Fin Rays - P: 1-8 7 Anal Fin Rays - R: 2-4
Caudal Fin Rays - P: (17)18 Caudal Fin Rays - RD: (8)9-10-11
Pectoral Fin Rays: (14)15-17 Caudal Fin Rays - RV: (6)7-~-9
Pelvic Fin Rays: 10 Lateral Scales: (57-)62-68
Vertebrae: 47-48 Gill Rakers:

Literature

54-60-70(-79)
28-11-34

Table 2. Size at apparent onset of selected developmental events for Catostomus ardens, as observed under low power
magnification. P = principal rays; R = rudimentary rays. Scales are lateral series. Rare or questionable extremes in parentheses.

Event or Onset or Formation Fin Rays First Formed Last Formed
Structure mmSL mmTL or Scales mmSL mmTL mmSL mmTL
Hatched: (7)8-11 (7)8-11 Dorsal- P: 13-15 14-16 14-16 17-19
Eyes Pigmented: 9-10 or * 9-lOor* Anal- P: 14-15 16-18 15-17 17-19
Yolk Assimilated: 12-13 12-14 Caudal- P: 12-13 12-14 13-14 14-15
Finfold Absorbed: 19 23 Caudal - R: 14-15 15-17 19-20 23
Pectoral Fin Buds: (7) or * (7) or * Pectoral: 14-15 16-18 15-18 17-22
Pelvic Fin Buds: 13-14(15) 14-15(16) Pelvic: 14-17 17-19 18-19 (19-)22
* before hatching Scales: 21-23 26-28 24-28 29-35

References: Andreasen and Barnes 1975, Baxter and Simon 1970, Baxter and Stone 1995, Jordan and Gilbert 1881, Jordan and
Evermann 1896, La Rivers 1962, Lee et al. 1980, McConnell et al. 1957, Miller 1952, Miller and Smith 1981, Minckley 1973, Sigler
and Miller 1963, Sigler and Sigler 1987. Simon 1946, Simpson and Wallace 1978, Tyus et al. 1982, Wheeler 1997. Personal
communication: 1981- T.e. Modde.

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