Esterases of earthworms--III. Electrophoresis reveals that Eisenia fetida (Savigny) is two species.

Polyacrylamide gel electrophoresis of esterases in earthworms classified as Eisenia fetida (Savigny) revealed the existence of two species. The classification based upon esterase electromorphs coincided with classification into two colour variants formerly described as subspecies under the names E. fetida typica and E. fetida unicolor (André, 1963). Two main groups of esterases, acetylesterases and carboxylesterases were found. Because of less variability within species and higher stability the acetylesterases are regarded as the most useful in taxonomy. Sterile hybrids, with hybrid esterase patterns were produced at a low rate in the laboratory, but were never found with certainty in the wild populations. Eisenia fetida (Savigny) and Eisenia unicolor (André) are the names proposed for the two species.