Abstract
Devils River minnow Dionda diaboli, listed as threatened (USA) and endangered
(Mexico), coexists with at least three congeners throughout its south Texas and northern
Mexico range. Monitoring of abundance, distribution, reproduction, and dispersion will
be improved with the capability to distinguish larval and juvenile Devils River minnows
from congeners and other cyprinids. I described and quantified various characteristics of
Devils River minnow early life stages at intervals ranging from time of hatch to 128 days to facilitate larval and juvenile identification. Distinguishing characteristics included
mid-lateral melanophores separate from a rounded basicaudal spot by Day 8, lateral snout
to eye melanophores by Day 16, initial coiling of intestine by Day 32, wedge-shaped
basicaudal spot by Day 64, and mid-lateral double dashes along lateral line and scale
borders by Day 128. Collectively, these characteristics and others described herein
provided a detailed account of Devils River minnow development through the juvenile
stage, but this information may be inadequate for confident identification until early
development of other cyprinids is described.
