The fringed darter, Etheostoma crossopterum, in the Cache River basin of southern Illinois (Percidae : subgenus Catonotus)

Etheostoma crossopterum is known for the first time in Illinois, occurring in streams of the Cache River basin of southern Illinois, The Cache River b asin population was considered Etheostoma squamiceps in all past accounts, but recent collections of breeding males (with diagnostic dorsal fin charac ters developed) permitted reidentification of this darter population as E, crossopterum. Nineteen sites were investigated (one in each of 19 streams) to determine if only E, crossopterum or both E, crossopterum and E, squamic eps occurred in the Cache River basin. Museum specimens were examined as we ll and, although no breeding males were present among the museum material e xamined, we concluded that all records off. squamiceps in the Cache River b asin refer to E, crossopterum based on 1997 collections of breeding males. In 1997, breeding occurred from at least 24: April to 21 May.