A taxonomic revision of the Allolobophora caliginosa complex (Oligochaeta, Lumbricidae): A preliminary study

The Allolobophora caliginosa complex includes a number of nominal taxa: A. caliginosa (Savigny, 1826), A. trapezoides (Duges, 1828), A. tuberculata Eisen, 1874, A. turgida Eisen, 1873, and A. nocturna Evans, 1946. There is wide disagreement as to the validity and rank of these taxa, and existing descriptions are generally inconsistent. In view of this confusion, about 4000 specimens of A. caliginosa s.l. collected from four regions of northern Spain and material in the collections of the Natural History Museum in London and the Canadian Museum of Nature in Ottawa were examined. Gross morphology was studied and the seminal vesicles were examined to determine whether sperm were present. I suggest that only a single species, A. caliginosa, should be maintained, with two subspecies, A. c. caliginosa and A. c. trapezoides. Allolobophora turgida and A. tuberculata are synonyms of A. caliginosa. Allolobophora nocturna-type specimens were not found in my sampling program and are very infrequent in museum collections, making it difficult to clarify the status of this taxon; it seems likely, however, that it is an ecotype with a localized distribution.