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

Skeletal Character Key for Postflexion Meso-
larvae that have been cleared and prefer-
ably stained for bone or cartilage (Fig. 6).

1. Standard length group (Fig. 4)
a. ~18 mm . . . . . . . . . . . . . . . . . C. /atipinnis

b. 17 mm . . . . . . . . . . . . . . . . . . . . . . . . . . 2
c. ::516 mm . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 (1). First (most anterior) interneural bone
(Fig. 8)
a. unclearly formed .................. 3
b. large and fan-shaped across top X. lexanus
c. large and angular or anvil-shaped with
a prominent posterior-directed projec-
tion or beak. . . . . . . . . . . . . . . . . . . . . . 4
d. small and blocky or angular with a small
to moderate posterior-directed projec-
tion or beak . . . . . . . . . . . . . . . . . . . . . . 5

3 (1,2). Number of vertebrae (including 4 for
Weberian complex)
a. 42-43 . . . . . . . . . . . . . . . . C. platyrhynchus
b. 44 .................. C. commersoni
C. platyrhynchus
c. 45-46................. C. commersoni
C. discobolus
C. platyrhynchus
X. lexanus

d. 47 . . . . . . . . . . . . . . . . . . . . . C. ardens
C. commersoni
C. discobolus
C. latipinnis
C. platyrhynchus
X. texanus

e. 48 . . . . . . . . . . . . . . . . . . . . . C. ardens
C. commersoni
C. discobolus
C. latipinnis
C. platyrhynchus
f. 49-50.................. C. discobolus
C. latipinnis
(rarely) C. platyrhynchus

4 (2). 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. lalipinnis

5 (2). Number of vertebrae (including 4 for
Weberian complex)
a. 42-44................ C. platyrhynchus
b. 45-50 . . . . . . . . . . . . . . . . . . C. discobolus
(rarely 49-50) C. platyrhynchus

Metalarvae .. adult complement of principal fin
rays present in dorsal, anal, and caudal fms,
but some preanal fin fold remaining (Figs.
18, 19; defmition abbreviated for species of
concern; there may be rare metalarval
specimens in which all finfold is lost but
not all pelvic fm rays or rudimentary caudal
fin rays are yet present). Separate skeletal
character key at end for confirmation of
identity or further diagnosis of specimens
cleared (and preferably stained) for bone.

1. Standard length (SL; Fig. 4)

a. 15 mm . . . . . . . . . . . . . . . . . . . . . . . . . . 2
b. 16 mm . . . . . . . . . . . . . . . . . . . . . . . . . . 4

c. 17 mm . . . . . . . . . . . . . . . . . . . . . . . . . . 9
d. 18 mm . . . . . . . . . . . . . . . . . . . . . . . .. 13

e. 19 mm . . . . . . . . . . . . . . . . . . . . . . . . . 20
f. 2Omm......................... 28
g. 21mm......................... 38

h. 22mm......................... 47
i. 23mm......................... 52

j. 24 mm . . . . . . . . . . . . . . . . . . . . . . . . . 53
k. 25mm.................. C.latipinnis

2 (1). Gut (Fig. 5)
a. essentially straight or with bend less than
90" (gut phase 1) ............ C. ardens
b. with at least 90" bend or partial s-shaped
loop (gut phase 2) ................. 3

3 (2). Pigmentation on lateral surfaces of
peritoneum
a. absent (Figs. 19, 88, 89) ............ 67
b. sparse or patchy (Figs. 18, 32, 33) . . . . . 72

4 (1). Gut (Fig. 5)
a. essentially straight or with bend less
than 90" (gut phase 1) ........ C. ardens
b. with at least 90" bend or partial s-shaped
loop (gut phase 2) .................. 5
c. with 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
d. 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) to gut with 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 development (gut
phase5) ............... C.discobolus

5 (4). Pigmentation on lateral surfaces of
peritoneum
a. absent (Figs. 19, 88, 89) ........ 67
b. sparse or patchy (Figs. 18, 32, 33,

74) .........................6

6 (5). Pigmentation on ventro-Iateral surfaces
of peritoneum

73