New species and new stage descriptions of Campsurus major species group (Polymitarcyidae: Campsurinae), with first report of silk-case construction in mayfly nymphs

Abstract

Campsurus major, C. argentinus and C. amapaensis sp. nov. form a monophyletic group supported by the following apomorphies in the male genitalia: robust pedestals with a widely rounded inner-posterior margin and a more acute and thinner outer margin, penes strongly sclerotised and curved ventrally, each lobe twisted outwards, and with a small membranous lobe on ventral margin. The nymphs of Campsurus major and C. argentinus and the female adult of C. major are described for the first time and illustrated here; the male adults of both species are redescribed. A new species, C. amapaensis, is described from male imagos. The following new synonymies are proposed: Campsurus argentinus Esben-Petersen (= C. pallidus Needham & Murphy, junior synonym) and C. major Needham & Murphy (= C. brasiliensis Traver, junior synonym). The nymphs of both species are reported to use silk to build soft cases and to glue substrate particles. A list of characters useful to distinguish the treated species from others in the genus is given.