Sexual Dimorphism in the Sucker Tribe Thoburnini (Cypriniformes: Catostomidae)

Sara Barck^1,* and Jonathan W. Armbruster²

¹Auburn University, Auburn, AL 36849. ²Auburn University Museum of Natural History, 101 Life Sciences Building, Auburn University, Auburn, AL 36849. *Corresponding author.

Southeastern Naturalist, Volume 25, Issue 1 (2026): 156-168

First published early online: 12 March 2026

Abstract
Sexual dimorphism is not always evident in fishes, but recognizing sex in the field can be important, especially when handling imperiled species. Previous literature has found few variable sexually dimorphic traits in species of the sucker (Catostomidae) genera Hypentelium, Thoburnia, and Vexillichthys. This study provides a resource for field identification of sex in these fishes. Through statistical analysis, we determined the differences between the sexes at 2 life stages in traits that are easily accessible in the field: pelvic-fin ray lengths, anal-fin height and length, and depressed dorsal-fin length. Our findings suggest the difference between the seventh and third pelvic-fin rays as well as depressed dorsal-fin length may provide consistent sex determination for mature fish in Hypentelium, Thoburnia, and Vexillichthys.

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