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

Computer-Interactive Key

The printed polychotomous keys in the first
edition of this guide (Snyder and Muth 1990)
were produced with the aid of DELTA (DE-
scriptive Language for TAxonomy) programs
for taxon description and keys (Dallwitz 1974,
1980; Dallwitz and Paine 1986). Characters
were encoded using the DELTA format (a
powerful, flexible, and widely accepted method
for recording descriptive taxonomic data for
computer processing) then transformed for use
by the program Key. Due to limitations of the
MS-DOS version of Key and the numerous over-
lapping characters of the species considered,
output was generated in segments, each restricted
to a select set of characters and species. These
were then edited to remove repeated branches and
phrases and assembled into a complete key for
each developmental phase.
However, in 1993, it became clear that the
guide and keys needed to be expanded to
include longnose sucker. Correction, update,
and expansion of the printed keys to include this
remaining UCRB species would have been a
long and arduous task and any further correc-
tions or updates in the future similarly difficult.
Fortunately, our prior experience with the
DELTA suite of programs had afforded us an
opportunity to experiment with an earlier DOS
version of lntkey, a DELTA program for
computer-interactive keys, which we found not
only easier to prepare, update, and expand than
traditional printed keys, but much more flexible
for the user. Even as we prepared the printed
keys, we considered preparation of data sets for
lntkey as an alternative, but at the time, conven-
tional printed keys were still deemed more
appropriate for publication and general use.
Since then, computer use has become pervasive
and computer-interactive keys have become
more common, especially for very similar
appearing and difficult to distinguish organisms.
Accordingly, we decided to adopt the modern
alternative. In anticipation ofthis update, a visit
was made in 1995 to M. Dallwitz (Common-
wealth Scientific and Industrial Research Organ-
ization Department of Entomology, Canberra,
Australia), the senior author of lntkey and other
DELTA programs, for assistance with pre-
paration of preliminary lntkey data sets, one for

each developmental interval through juveniles
up to 40 mm SL.
Most computer-interactive keys are data
sets designed to be used with specific commer-
cial, public-domain, or proprietary host pro-
grams. The features and flexibility of several
alternative computer-interactive key programs
were compared to lntkey. Based on this compar-
ison and our prior experience with lntkey, we
decided to continue developing our updated and
expanded keys for that program. The latest
versions of lntkey (Dallwitz et al.1993 onwards,
1995 onwards), DELTA Editor (Dallwitz et al.
1999 onwards), and associated programs and
files were downloaded from the Internet
(http://biodiversitv.uno.edu/delta/). DELTA
Editor was used to develop and refine a
progressive series of data sets for UCRB catos-
tomid larvae and the derived data files required
by lntkey. Rich-text files to be accessed through
lntkey for background information, beginning
instructions, and other information were pre-
pared or modified with a word processor. Image
files used by lntkey were created or modified
from scanned files with a computer drawing or
presentation program.
Like the former printed keys and as men-
tioned above, early and intermediate versions of
the computer-interactive key were actually a set
of six keys, one for each developmental period
or phase (including a single-character key for
embryos-egg diameter). The intermediate ver-
sions were demonstrated and discussed with
opportunities for hands-on experimentation at
three technical meetings in 2002 (Recovery Pro-
gram Researchers Meeting, Colorado-Wyoming
Chapter of the American Fisheries Society, and
Larval Fish Conference). The interest generated
in these keys, and computer-interactive keys in
general, during these presentations and hands-on
sessions was encouraging. Participant feedback,
however, suggested that the keys could be best
improved by combining them into one key
covering all developmental intervals.
Accordingly, the separate data sets and keys
were combined into one with either characters or
taxa subdivided according to developmental
interval and size. Near final versions of the data
set and key were prepared with subdivided taxa,

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