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

METHODS

Specimen Data and Observations

Specimens were analyzed for counts,
measures, developmental state, structural
differences, and pigment distribution. Fig. 4
illustrates the various measurements, fm ray
counts, and myomere counts that were made
on at least two specimens, if available, in
each 1-mm TL (total length) interval
throughout the larval period of each species.
Thereafter, to a length of about 50 mm TL,
one or more specimens were similarly pro-
cessed for each 5-mm interval, if available.
Specimens were studied under low-power
stereo-zoom microscopes with measuring eye-
piece reticles and various combinations of
reflected, transmitted, and polarized light.
Magnification was adjusted before each series
of measurements to calibrate the scale in the
eyepiece against a stage micrometer for direct
measurement. Measurements were made to
the nearest 0.1 mm and occasionally to half
that unit. Remeasurement of selected speci-
mens by a second observer indicated that
most measurements are repeatable to within
0.1 mm. Most measurements are reported as
a percentage of standard length (% SL) but
are readily converted to percent total length
by dividing the length of interest (as % SL)
by total length (AS to PC, as % SL), and
multiplying by 100. Some meristic data were
obtained from specimens cleared and stained
for skeletal study and from available adults.

Size at apparent onset of selected devel-
opmental events was documented for fully
analyzed and cursorily examined specimens.
Selected events were hatching, attainment of
eye pigment, formation of pectoral and pelvic
fin buds, loss of yolk and preanal finfold,
formation of first and last principal fm rays in
each of the median fins, formation of first
and last fin rays in the paired fins, formation
of first and last rudimentary rays of the
caudal fin, and initial and complete formation
of lateral scales on the body. For each speci-
men developmental phase (e.g., Protolarva)
and extent of gut folding were also deter-
mined. The latter was classified as one of
five gut phases (Fig. 5). Changes in other
structures were only casually noted.

Drawings, including dorsal, lateral, and
ventral views, were prepared for the begin-
ning and middle of each larval phase (flexion
and postflexion mesolarvae treated as one
phase) and the juvenile period (young-of-the-
year portion) for all species except white
sucker to document typical body form and
pigmentation. Enlarged photographs of
typical specimens were traced to assure
accurate body proportions. Various struc-
tures were checked and additional detail was
added to drawings while specimens were
examined under a microscope. Final draw-
ings were idealized (e.g., closed or frayed fms
opened and smoothed and curved bodies
straightened). If necessary, melanophore dis-
tribution was modified using additional refer-
ence specimens to represent a more typical
pattern. In addition, pigmentation variation
was studied by sketching observed patterns
and loosely noting their frequency.

Selected postflexion mesolarvae, meta-
larvae, and juveniles were cleared and stained
for examination of potential osteological char-
acters and vertebra counts as well as to verify
fm meristics. Shape and size of the fronto-
parietal fontanelle, interneurals, and anterior-
dorsal maxillary projections; position of man-
dibles relative to maxillae; and, to a less
consistent extent, angle at which the base of
postcleithra extend from the cleithra (Fig. 6).
Mesolarvae were stained with alcian blue for
cartilage and metalarvae and juveniles with
alizarin red for bone using the procedures
given on the following pages.

Keys were produced with the aid of the
DELTA (DEscriptive Language for TAxon-
omy) system of computer programs (Dallwitz
1974, 1980; Dallwitz and Paine 1986). Char-
acters were encoded using the DELTA for-
mat then transformed for use by the program
KEY. Due to limitations of the current MS-
DOS version of KEY and the numerous over-
lapping characters of the species considered,
output was generated in segments, each res-
tricted to a select set of characters and
species. These were then edited to remove
repeated branches and phrases and assemb-
led into a complete key for each develop-
mental phase.

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