7723

• UCREFRP Catalog Number: 7723
• Author: Snyder, D. E. and R. T. Muth
• Title: Editor
• USFW Year: Series
• USFW - Doc Type: 1990
• Copyright Material: NO

7 (6). Number of vertebrae (including 4 for
Weberian complex)
a. 44-46 . . . . . . . . . . . . . . . . . C. commersoni

b. 47-48 . . . . . . . . . . . . . . . . . . . . . C. ardens
C. commersoni
C. latipinnis
c. 49-50................... C. latipinnis

8 (5). First (most anterior) interneural bone
(Fig. 8)
a. large and fan-shaped across top X. lexanus
b. large and angular or anvil-shaped with a
prominent posterior-directed projection
orbeak ................. C./atipinnis

9 (1). Frontoparietal fontanelle (Fig. 7)
a. narrow,::530% of fontanelle length .... 11
b. moderately wide, 31-40% of fontanelle

length ......................... 10
c. wide, 41-47% of fontanelle length
.................... C./atipinnis
d. very wide, ~48% of fontanelle length
(often over 60% and somewhat oval in
shape) . . . . . . . . . . . . . . . . . . . X.lexanus

10 (9). F'rrst (most anterior) interneural bone
(Fig. 8)
a. large and angular or anvil-shaped with
a prominent posterior-directed projec-
tion or beak; anterior ends of mandibles
(from ventral view of head) well anter-
ior, at least mid-distance between pos-
terior and anterior ends of maxillae;
anterior-dorsal maxillary projections
small and rounded to reduced and
almost absent ............ C. latipinnis
b. small and blocky or angular with a small
to moderate posterior-directed projec-
tion or beak; anterior ends of mandibles
(from ventral view of head) well poster-
ior, much closer to posterior than anter-
ior ends of maxillae; anterior-dorsal
maxillary projections prominent and

pointed ........................ 11

11 (3,6,9,10). Number of vertebrae (including 4
for Weberian complex)
a. 42-44................ C. platyrhynchus
b. 45-50 . . . . . . . . . . . . . . . . . . C. discobolus
(rarely) C. platyrhynchus

Juveniles ~O mm SL -- no fmfold remaining
(Figs. 20, 21; definition abbreviated for
species of concern; there may be rare
metalarval specimens in which all finfold
is lost but not all pelvic fin rays or rudi-
mentary caudal fm rays are yet present).
Separate skeletal character key at end for
confirmation of identity or further diag-
nosis of specimens cleared (and preferably
stained) for bone.

1. Standard length (SL; Fig. 4)
a. 17-18 mm ............. C. commersoni

b. 19 mm . . . . . . . . . . . . . . . . . . . . . . . . . . 2
c. 20 mm .. . .. .. .. .. .. .. .. .. .. .. . .. 3
d. 21 mm . . . . . . . . . . . . . . . . . . . . . . . . . . 5
e. 22 mm . . . . . . . . . . . . . . . . . . . . . . . .. 10

f. 23-25 mm ...................... 23

g. 26-28 mm ...................... 40
h. 29-31 mm ...................... 58
i. 32-34 mm ...................... 71
j. 35-37 mm ...................... 76
k. 38-40 mm ...................... 85

2 (1). Gut (F'Jg. 5) with
a. at least 90" bend or partial s-shaped loop
(gut phase 2) . . . . . . . . . . . . . . . C. ardens
b. full loop (s-shape to near anterior end
of visceral cavity) but with neither limb
of loop completely across over ventral
midline (gut phase 3) . . . . . . . . . . . . . . . 4
c. at least one limb of loop fully across
ventral midline but not yet with both
limbs across fully to opposite side (gut
phase 4) .............. C. commersoni

3 (1). Gut (Fig. 5) with
a. full loop (s-shape to near anterior end
of visceral cavity) but with neither limb
of loop completely across over ventral
midline (gut phase 3) or gut with at
least one limb of loop fully across
ventral midline but not yet with both
limbs across fully to opposite side (gut

phase 4) ........................ 4
b. both limbs of loop across midline fully
to opposite side (four segments of gut
crossing nearly perpendicular to body
axis) or with more extensive coil devel-
opment (gut phase 5) . . . . . C. commersoni

4 (2,3). Mouth
a. low terminal (at or below bottom-of-eye
level) to slightly subterminal (mouth,
including upper lip, not the most anter-
ior portion of snout) (Figs. 20, 34) ... 104
b. distinctly subterminal (mouth notably
posterior to most anterior portion of
snout) (F'Jg. 63) ......... C. commersoni

5 (1). Gut (Fig. 5) with
a. full loop (s-shape to near anterior end
of visceral cavity) but with neither limb
of loop completely across over ventral
midline (gut phase 3) . . . . . . . . . . . . . . . 7
b. at least one limb of loop fully across
ventral midline but not yet with both
limbs across fully to opposite side (gut

phase 4) ........................ 6
c. both limbs of loop across midline fully
to opposite side (four segments of gut
crossing nearly perpendicular to body

82