Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


A systematic study of the North American percid fish Percina (Alvordius) maculata (Girard) was undertaken to determine the extent and pattern of geographic variation, subspeciation, and sexual dimorphism. A brief nomenclatorial history is presented, the species is redescribed, and variation, distribution, habitat, and subgeneric relationships are discussed. Other than dorsal fin pigmentation, absence of modified midventral scales in females, and limited intrapopulational sexual dimorphism in a few morphometric characters, no variation in most of the thirty-nine characters examined is present between males and females. Morphometrics exhibited no pattern of geographic variation; however, meristic characters revealed a major trend in geographic variation. Lateral-line, transverse, caudal peduncle, and modified midventral scales exhibited clinal variation with highest counts in the southern part and lowest counts in the northern-most part of the range of P. maculata. Less variable characters showed this trend to a slight degree or not at all. The reverse trend, higher counts in the north and lower in the south, appeared in dorsal and anal fin-ray counts. P. maculata is distributed in the Mobile Bay, Pearl River, Lake Pontchartrain, and Calcasieu River drainages of the Gulf slope, the lower and upper Mississippi River drainages, the Ohio River, the Great Lakes system, and the Red River of the North of the Hudson Bay drainage. This species is an inhabitant of clear streams with sand and gravel bottoms and is typically associated with the margins of stream pools. Within the subgenus Alvordius, P. maculata is most closely related to P. pantherina as interpreted from meristics, pigmentation patterns, and zoogeography.