SUCKERS - CATOSTOMIDAE


1a. Dorsal fin rays more than twenty (Fig. 30A)........................................................................ 2

1b. Dorsal fin rays 10-15 (Fig. 30B)......................................................................................... 8


2a. Lateral-line scales more than fifty; lips papillose
(Fig. 31C); eye closer to back of head than tip of snout................ Blue Sucker, Cycleptus elongatus

2b. Lateral-line scales fewer than fifty; lips plicate or
smooth (Fig. 31A or B); eye closer to tip of snout than
back of head ....................................................................................................................... 3


3a. Color usually dull bronze or olivaceous; lower fins
dark-pigmented; anterior fontanelle (on midline of top of
head, between nostrils and eyes)closed in adults; lower
margin of subopercle evenly curved, not angular(widest
at midpoint of its length; Fig. 32A); pelvic rays usually
10-11, anal rays 8-9, sum of pelvic and anal rays eighteen
or more............................................................................................................................... 4

3b. Color silvery white; lower fins cream-colored or clear;
anterior fontanelle open in adults; marginal curvature of
subopercle somewhat angular (widest anterior to midpoint
of its length; Fig. 32B); pelvic rays usually 8-10, anal rays
7-9, sum of pelvic and anal rays usually seventeen or fewer
except in C. velifer ............................................................................................................... 6


4a. Mouth terminal and oblique; anterior tip of upper lip
nearly level with lower edge of eye; lips thin; upper jaw
about as long as snout .................................................... Bigmouth Buffalo, Ictiobus cyprinellus

4b. Mouth ventral and horizontal; tip of upper lip far below
level of eye; lips fleshy; upperjaw shorter than snout................................................................ 5


5a. Distance from tip of lower jaw to end of maxilla equal
to or greater than eye diameter in young, about twice eye
diameter in adults; height of anterior rays in dorsal and anal
fins often less than head length; greatest depth of body
2.6-3.2 into standard length; not notably ridge-backed ...................... Black Buffalo, Ictiobus niger

5b. Distance from rip of lower jaw to end of maxilla less than
eye diameter in young, about equal to eye diameter in adults;
height of anterior dorsal and anal fin rays greater than head
length; greatest depth of body 2.2-2.8 in standard length;
back highly arched, ridge-like............................................. Smallmouth Buffalo, Ictiobus bubalus


6a. Mouth farther forward than nostrils; front of lower lip
rounded; distance from tip of snout to anterior nostril greater
than diameter of eye; lateral line scales usually 37 or more .............. Quillback, Carpiodes cyprinus

6b. Mouth almost directly below nostrils; front of lower lip
with small, median, nipple-like projection (Fig. 31B); distance
from tip of snout to anterior nostril less than diameter of
eye; lateral-line scales 34-36 ................................................................................................ 7


7a. Anterior (longest) rays of dorsal fin exceeding basal
length of fin; body depth goes less than 2.7 times into
standard length; anal rays 8-9, pelvic rays usually ten .......... Highfin Carpsucker, Carpiodes velifer

7b. Anterior (longest) rays of dorsal fin shorter than basal
length of fin; body depth goes 2.7 or more times into
standard length; anal rays 7-8, pelvic rays usually nine ........... River Carpsucker, Carpiodes carpio


8a. Lips papillose (Fig. 31C) ............................................................................................... 9

8b. Lips plicate (Fig. 33)....................................................................................................... 10


9a. Lateral-line scales 45-54; distance from hind margin
of orbit to upper end of gill cleft contained 2.0 or more times
in snout length; pelvic rays usually nine .................... Northern Hogsucker, Hypentelium nigricans

9b. Lateral-line scales more than 55; distance from hind
margin of orbit to upper end of gill cleft contained less than
2.0 times in snout length; pelvic rays usually ten ............. White Sucker, Catostomus commersonii


10a. Lower lip thin, not coarsely striated, its width at
center contained 2.5 or more times in width of gape (Fig. 33A);
sides usually striped by rows of dots; air bladder divided into
two chambers ................................................................. Spotted Sucker, Minytrema melanops

10b. Lower lip thick, coarsely striated, its width at center
contained less than 2.5 times in width of gape; sides never
conspicuously striped by rows of dots; air bladder divided
into three chambers............................................................................................................ 11


11a. Pharyngeal arch fragile, with slender teeth in comblike
series (Fig. 7A); no semicircular line of melanophores on caudal
lobes; caudal fin red or not.................................................................................................. 12

11b. Pharyngeal arch heavy, with molarlike teeth (Fig. 7B);
last caudal scales outlined by melanophores, forming a
semicircular line of pigment on each lobe of caudal fin;
caudal fin red in life ...................................................... River Redhorse, Moxostoma carinatum


12a. Posterior margin of lower lip notched rather than
straight across, the right and left halves meeting at an
obtuse angle (Fig. 33B or C); plicae of lower lip not broken
by transverse grooves; upper lip not thickened at center;
caudal fin not red in life...................................................................................................... 13

12b. Posterior margin of lower lip nearly straight or convex
(Fig. 33D); plicae of lower lip partly broken by transverse
grooves; upper lip thickened medially in most examples;
caudal fin bright red in life ............................ Shorthead Redhorse, Moxostoma macrolepidotum


13a. Lateral-line scales fewer than 45; pelvic rays usually
nine; caudal peduncle deep, its least depth going less than
two times into its length (distance from anal fin origin to
base of caudal fin) ................................................... Golden Redhorse, Moxostoma erythrurum

13b. Lateral-line scales usually 44 or more; pelvic rays
usually ten; caudal peduncle slender, its least depth going
two or more times into its length (distance from anal fin
origin to base of caudal fin)............................................. Black Redhorse, Moxostoma duquesnii