Date of Award

Spring 5-2015

Degree Type


Degree Name

Doctor of Philosophy (PhD)


Biological Sciences

Committee Chair

Mac H. Alford

Committee Chair Department

Biological Sciences

Committee Member 2

George F. Pessoney

Committee Member 2 Department

Biological Sciences

Committee Member 3

Jacob F. Schaefer

Committee Member 3 Department

Biological Sciences

Committee Member 4

Brian R. Kreiser

Committee Member 4 Department

Biological Sciences

Committee Member 5

Carl A. Reese

Committee Member 5 Department

Geography and Geology


A recent taxonomic revision of the Neotropical catfish genus Rhamdia (Pisces: Siluriformes: Heptapteridae) reduced a number of described species to synonymy, especially under a broadly circumscribed R. quelen. Evidence is presented here from DNA sequence data, external and internal morphology, and morphometrics that argues for the recognition of R. guatemalensis in Central and northern South America and R. saijaensis and R. cinerascens in the Pacific drainages of Colombia and Ecuador, respectively. The DNA data indicate that all trans-Andean samples form a monophyletic group, within which there are separate clades corresponding to R. laticauda and the synonymized R. guatemalensis, R. saijaensis, and R. cinerascens. The morphometric data substantiate the phylogenetic groupings, and in external morphology, each putative species has diagnostic characters. The external and internal morphological differences and phylogenetic relationships indicate that these groups are both recognizable and represent independent lineages, which argue for their recognition as species.