Heterotrissocladius Spärk, 1923

Namayandeh, Armin, Hudson, Patrick L., Bogan, Daniel L. & Hudson, John P., 2024, Chironomidae (Diptera: Insecta) of Alaska, USA, with descriptions of new species and a checklist, Zootaxa 5511 (1), pp. 1-95 : 60

Heterotrissocladius Spärk, 1923

We collected Heterotrissocladius changi Saether, 1975 from several localities. The adult males were collected from Antler River, Spike Creek, and Margaret Lake in Southeast Alaska in late April and May. Two larvae were collected from Spike Creek and a first-order stream in Juneau in May and July. Webb et al. (2022) reported this species from the Central bioregion of Alaska but did not give a specific location. Saether (1975) suggested there may be two species involved in his description. He also characterized their habitat as lake-dwelling in contrast to some of the habitats we collected our material. Moore (1979) found H. changi to be the most frequently encountered species in the Yellowknife River at its junction into the Great Slave Lake in subarctic Northwestern Canada.

Adults and larvae of Heterotrissocladius maeaeri Brundin, 1949 are reported from the littoral zone of Toolik Lake by Hershey (1985) where they were one of the most abundant species collected on bare sediments. The species appears to have a one-year life cycle with its emergence in the first half of August. The larvae of H. maeaeri group were reported by Sikes et al. (2016) from St. Matthew Island. Species in the maeaeri group are typical of ultraoligotrophic or strongly oligotrophic lakes ( Saether 1975). The larvae of Heterotrissocladius marcidus group have been reported from the Kuskokwim River (Western region) and from a tributary of the Stuyahok River (Southwestern bioregion) in Arctos (2023). We have larval collections of H. marcidus group from many lakes, rivers, and streams in Southeast Alaska, several streams in Southwest Alaska and Lucille Creek in Wasilla. We have also collected the larva of H. marcidus group in the Yukon River in Yukon-Charley Rivers National Preserve.

Our other collection of larvae come from the Taku River in Southeast and belong to an unknown species in the Heterotrissocladius subpilosus group.