The immature stages and biology of the unusual North American arctic caddisfly Sphagnophylax meiops, with consideration of the phyletic relationships of the genus (Trichoptera: Limnephilidae)

Abstract

Larvae and pupae of Sphagnophylax meiops Wiggins and Winchester, previously unknown, are identified from a transient arctic tundra pool near Tuktoyaktuk, Northwest Territories, Canada (69 °29′N, 132 °35′W). Surface water persisted in the basin of the pool, where larvae were evident for about 2 weeks in June, then receded into water-saturated organic materials above the permafrost, where larvae completed feeding, growth, and metamorphosis. The species has a univoltine life cycle, and adults emerge over a 5-week period from late June to the end of July. Adults are brachypterous and evidently flightless. Assignment of the genus Sphagnophylax to a tribe within the subfamily Limnephilinae is unusually complex. Long bristles on the forewings are synapomorphic with the Chaetopterygini, but female genitalic structure suggests affinity with the Limnephilini. The genitalic structure of males indicates no clear relationship with the Limnephilini, but similar tendencies in some characters suggest distant affinity with the genus Philarctus, which is itself somewhat aberrant within the Limnephilini. The significance of these tendencies cannot be fully assessed until phylogenetic analysis of the subfamily Limnephilinae has been carried out. The larval gill structure consisting of multiple filaments in Sphagnophylax is shared with all of the Limnephilini, and is probably an apomorphic character. The genus Sphagnophylax is assigned to the tribe Limnephilini, and is interpreted as a relict group.