The female and larva are described and the male and pupa redescribed for Orthocladius lignicola Kieffer. A lectotype is designated for a pupa belonging to the syntypic series. O. tryoni Soponis, 1977 is synonymized with O. lignicola. A new genus, Symposiocladius, is erected for the species, and a systematic placement close to Orthocladius, Synorthcladius and Stackelbergina is postulated. The larval habit of mining in submerged wood is discussed in relation to a brief review of previous records.