Morphological investigation of the Sand Shiner Notropis stramineus (Cope, 1865)

Authors: Amanda Pinion, Daemin Kim, Kevin Conway

Year: 2019

Abstract

In recent years, investigations of widespread North American freshwater fishes have revealed significant levels of cryptic diversity, especially in minnows and shiners of the family Cyprinidae. The Sand Shiner, Notropis stramineus (Cope, 1865) is a small North American minnow with an expansive distribution east of the Continental Divide present abundantly in a portion of the southwestern U.S. to northern Mexico. Though N. stramineus is currently regarded as a single species, previous taxonomic authorities recognized two subspecies (N. s. stramineus and N. s. missuriensis) still recognized as valid by some authors. This two subspecies classification is based largely on minor differences in scale-row counts between individuals inhabiting tributaries to the Great Lakes, upper Mississippi and Texas gulf coast river systems (N. s. stramineus) and those inhabiting the Missouri and Arkansas River systems (N. s. missuriensis). Analysis of an unpublished, multi-locus genetic data set has revealed the presence of multiple genetically distinct lineages geographically incompatible with the aforementioned subspecies designations. These results instead suggest that N. stramineus may represent a super-species-complex, comprising multiple (4+) similar looking, yet genetically distinct species, the majority of which have yet to be formally recognized and diagnosed with phenotypic characters. To uncover morphological traits useful for distinguishing between putative members of this super-species-complex, we have analyzed geometric morphometric landmark-derived characters to investigate whether consistent phenotypic variation exists across the range of N. stramineus sensu lato and whether patterns of phenotypic variation are congruent with geography and genetic lineage membership.