We redescribe Catostomus utawana using specimens from an extant population and museum collections from the Adirondack region of New York and compare it to the widely distributed Catostomus commersonii. These species differ from each other in body depth, relative lengths of pectoral, anal, and pelvic fins, in the lengths of the dorsal-fin and anal-fin bases, and in several characteristics related to head shape and body depth. Catostomus utawana females in breeding condition have well-developed pearl organs on the anal fin, ventral lobe of the caudal fin, and on most of the scales found on the ventral half of the body posterior to the dorsal fin. Catostomus commersonii females in breeding condition usually lack pearl organs. Catostomus utawana males in breeding condition are extensively covered in pearl organs, whereas the pearl organs on C. commersonii males are typically limited to the anal and caudal fins, scales posterior to the dorsal fin, and on the head. Catostomus utawana males in breeding condition have a gold mid-lateral stripe and a gold patch above each eye; breeding females lack gold coloration. Catostomus utawana males and females lack red coloration throughout their spawning season. We propose using the common name of Summer Sucker for C. utawana.