Biogeography and taxonomy of terrestrial Enchytraeidae (Oligochaeta) in northern Sweden, with comparative remarks on the genus Henlea

Enchytraeids were collected at 14 localities along a latitudinal transect f rom Abisko (68 degrees 21' N), Lapland, to Sandviken (61 degrees 40' N), Ga strikland. A total of 34 species were identified including one (Fridericia sohlenii) new to science and three never recorded previously in Sweden: Bry odrilus parvus Nurminen, 1970 and Henlea glandulifera Nurminen, 1970 (both Arctic-Alpine) and Cernosvitoviella ampullax Klungland & Abrahamsen, 1981 ( so far endemic to Scandinavia). The high number of species recorded in Abis ko (18 during this survey) must be referred to the particularly varied geol ogy of the area. The description of H. glandulifera is augmented. A compara tive study of the clitellar gland cells, coelomocytes, preclitellar nephrid ia, oesophageal appendages, and glandular differentiations of the postclite llar intestinal wall, in this and five other species of Henlea (based on ma terial from various countries), is also presented, with a view to enhancing species delimitation in a genus which is well represented in the Arctic bu t prone to ecophenotypic variation. The northern limits of distribution of the 34 species in Scandinavia are analyzed.