Date of Award


Document Type


Degree Name

Master of Science (MS)

Legacy Department



Morse, John


The genus Hydrospsyche Pictet sensu stricto in North America is divided into three species groups, the Hydrospyche cuanis Ross Group Ross, the Hydropsyche depravata Hagen Group Ross, and the Hydropsyche scalaris Hagen Group Banks. Thirty-one of thirty-six described species are recognized in the Hydropsyche scalaris Group. Examination of adult males resulted in 5 junior subjective synonyms and one possible new species based on a single exemplar from Sevier County, Utah. Hydropsyche bidens Ross 1938, H. orris Ross 1938, and H. alvata Denning 1949 are junior synonyms of Hydropsyche incommoda Hagen 1861. Hydrospyche rossi Flint, Voshell and Parker, 1979 and H. fenestra Lago and Harris 2006 are junior synonyms of H. simulans Ross 1938. A key to the adult males is provided and intraspecific variation illustrated. Scanning electron microscopy, cross-sectioned material, careful hand dissections, and a summary of relevant literature were used to formulate a revised description of phallic morphology. The phallobase forms the copulatory organ with the endotheca indistinguishable. The sclerotized, non-eversible, internal atrium of Hydropsyche s.s. is considered phallicata based on the presence of internal longitudinal muscle and its attachment points. Parameres and endophallus are absent. Conflicting and supporting evidence for alternative interpretations of the phallic apparatus is considered.

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