The mayflies of Saskatchewan

Abstract

One hundred-seven species belonging to 54 genera and 18 families of Ephemeroptera are reported from Saskatchewan. An additional two species, Callibaetis skokianus Needham and Procloeon rivulare (Traver), are reported in the literature but their presence in Saskatchewan cannot be confirmed. Twenty-seven species are reported from Saskatchewan for the first time: Acerpenna sp. A Jacobus and McCafferty, Baetis bicaudatus Dodds, B. bundyae Lehmkuhl, B. intercalaris McDunnough, Centroptilum album McDunnough, C. conturbatum McDunnough, Cloeon dipterum (Eaton), Plauditus cestus (Provonsha and McCafferty), P. gloveri McCafferty and Waltz, Procloeon ingens (McDunnough), Pr. irrubrum Lowen and Flannagan, Pr. sp.1, Pr. rufostrigatum (McDunnough), Pr. simplex (McDunnough), Baetisca laurentina McDunnough, Brachycercus edmundsi Soldan, Caenis hilaris (Say), Cercobrachys cree Sun, Webb and McCafferty, Ephemerella needhami McDunnough, Eurylophella bicolor (Clemens), Serratella serrata (Morgan), S. tibialis (McDunnough), Leucrocuta maculipennis (Walsh), Asioplax edmundsi (Allen), Siphloplecton basale (Walker), Parameletus chelifer, and Siphlonurus sp. 1. Cercobrachys cree is new to science.

Species-level identification keys are provided for all known larvae, except for those of Leptophlebia Westwood, and for all known adult males except for those of Plauditus Lugo-Ortiz and McCafferty. Diagnostic characters useful for differentiating each species from other Saskatchewan species, selected references, Saskatchewan distribution maps, biological notes, material examined, and illustrations of taxonomically important characters, are provided for each species.

Three main faunal zones are observed: Saskatchewan River system, lentic, and boreal forest. Within each of the faunal zones several sub-zones occur. The distribution patterns observed in mayflies correspond closely to those observed in other groups of aquatic insects, except that few montane species are present in the Cypress Hills.

Some of the large river-specialist species of mayflies present in pristine portions of the Saskatchewan River system have been extirpated from much of their North American range. Analetris eximia Edmunds, Macdunnoa nipawinia Lehmkuhl and Lachlania saskatchewanensis Ide are known from only a few North American locations and should be considered 'rare'. Anepeorus rusticus McDunnough and Acanthamola pubescens Whiting and Lehmkuhl are endangered and possibly extinct.