Revision of the Onocosmoecus Unicolor Group (Trichoptera: Limnephilidae, Dicosmoecinae)

The genus Onocosmoecus, by current definition, comprises the unicolor group and the frontalis group (Schmid 1980, occidentalis group = unicolor group; Wiggins 1977). From a separate study of generic relationships within the Dicosmoecinae (G. B. Wiggins & 0. S. Flint, in prep.), it is clear that Onocosmoecus in this broad sense is not monophyletic. The frontalis group will be considered in a subsequent paper, but in the interim the two western North American species of which it is composed, 0. frontalis (Banks) and 0. schmidi (Wiggins), remain nominally under Onocosmoecus. Thus, in final analysis, this study of the unicolor group will constitute a revision of the genus Onocosmoecus s.s., and the generic name is used here in that restricted sense. Among the genera of the limnephilid subfamily Dicosmoecinae, Onocosmoecus S.S. is one of the most widespread, represented across the whole of northern North America from Newfoundland to Alaska, south in the western mountains to California, and across the Bering Strait to Kamchatka. They are rather large caddisflies, not often found in abundance but by no means rare. Larvae occur in cool lotic habitats, and also in the littoral zone of cool lakes, where they are detritivorous. Seven species have been assigned to the genus in the past but reservations concerning their validity have been expressed by several authors (e.g., Schmid 1955, 1980; Flint 1960; Wiggins 1977). Because no analysis of types or of long series of specimens has been undertaken, identity of the putative species has always been doubtful. The purpose of the present study was to undertake that analysis.