Gerromorpha (Hemiptera: Heteroptera) in southern Illinois: Species assemblages and habitats

Abstract

Gerromorphan species assemblages in southern Illinois were studied at 86 sites representing eleven habitat types (pond, lake, swamp, temporary pool, large river, small river, muddy eutrophic permanent stream, clear rocky permanent stream, clear rocky temporary stream, roadside ditch, and spring) from mid-May 1988 through late July 1991. Assemblages varied in size and composition, with the most diverse found in clear rocky permanent streams. Phenograms tended to cluster major habitat types (e.g., ponds, lakes) based on taxon presence/absence and to cluster the more commonly co-occuring species based on their presence/absence at collection sites. These phenograms indicated the presence of natural guilds of species in different habitat types. Some taxa were generalists based upon their widespread occurrence in a variety of both lentic and lotic habitat types, whereas others exhibited a narrower range of habitat use. Collections included 32 species in five families (Gerridae, Hebridae, Hydrometridae, Mesoveliidae, and Veliidae), which represented 91.4-95.2% of the estimated actual species present based on the species accumulation curve and four species richness estimators. These data demonstrate the presence of distinctive guilds of gerromorphans in different habitats in southern Illinois.