A systematic evaluation of the Waccamaw darter, Etheostoma perlongum (Hubbs and Raney) : with comments on relationships within the sybgenus Boleosoma (Percidae: Etheostomatini)

A study was conducted to determine systematic relationships between the Waccamaw darter, Etheostoma perlongum, and other closely related members of the subgenus Boleosoma (primarily E. olmstedi) using horizontal starch-gel electrophoresis and standard morphological techniques. Darter populations were sampled from Lake Waccamaw, the Waccamaw River, and several additional major drainages. Also, one population each of E. longimanum and E. podostemone were included for biochemical comparison. A total of 46 alleles were resolved for the 18 loci examined.

Populations from the Waccamaw and Pee Dee drainages clustered phenetically with an average identity of 0.983. Populations from the Cape Fear, Santee, and Neuse drainages were somewhat more divergent, and the single population from the Oswego drainage of New York, clustered apart from all others.

Several unique alleles were present in the Waccamaw drainage; however, this condition was also evident in E. olmstedi populations from various other drainages. In addition, both morphological and biochemical data indicated clinal variation between darter populations in Lake Waccamaw and those in the Waccamaw River. This clinal variation, coupled with the high degree of genetic similarity between darters from the Waccamaw and other drainages sampled in the southeast, suggests that E perlongum and E. olmstedi are conspecific. The Waccamaw darter is recognized as a unique ecomorph. Morphological characteristics distinguishing the Waccamaw darter from other Boleosoma (primarily scale patterns and numbers) are likely controlled to a large degree by environmental conditions.