Descriptions and ecological notes on seven new species of Cladotanytarsus (Chironomidae: Diptera) collected from an experimentally acidified lake

Descriptions of male and female imagines and pupal exuviae are given for Cladotanytarsus tribelus sp.n., Cladotanytarsus fusiformis sp.n., Cladotanytarsus pinnaticornis sp.n., Cladotanytarsus muricatus sp.n., Cladotanytarsus elaensis sp.n., and Cladotanytarsus daviesi sp.n. Included also is the description of the parthenogenetic female of Cladotanytarsus aeiparthenus sp.n. and its pupal exuviae. Diagnostic characters are selected to separate males, females, and pupae of similar species. In addition, the pupal diagnosis to Cladotanytarsus has been revised to accommodate the 21 Holarctic species included in a pupal key. All type specimens were collected primarily from lake 223, an experimentally acidified system at the Experimental Lakes Area, northwestern Ontario. Information is also provided on the phenologies, depth distributions, and effects of pH changes on the tolerance ranges of the seven new species.