Henlea yukonensis (Oligochaeta: Enchytraeidae), a new species from the Yukon Territory, with comments on Henlea Michaelsen, 1889 and Punahenlea Nurminen, 1980

Henlea yukonensis Tynen and Coates, sp.nov., a large enchytraeid 10–60 mm long and 2 mm in diameter, is described from the western foothills of the Richardson Mountains. Henlea yukonensis is distinguished from H. udei (Eisen, 1904), a species known only from Alaska, by spermathecal form and by the locations of the intestinal diverticula and dorsal blood vessel origins. Henlea yukonensis could be included in Hepatogaster Cejka, 1910, a subgenus of Henlea Michaelsen, 1889 characterized by intestinal diverticula with a multitubular substructure, if that form of intestinal diverticulum were shown to be apomorphic in Henlea. This form of diverticulum is described only in a few Siberian and North American species of Henlea: H. ochracea (Eisen, 1878) sensu Welch, 1919, H. moderatoidea Altman, 1936, and H. udei (Eisen, 1904), Subgeneric classification within Henlea awaits the resolution of diagnostic character states and of character polarities for the genus as a whole. Setal size distribution, oesophageal append...