Descriptions of two new Iridodrilus species and a re-examination of the earthworm genera Heliodrilus Beddard, Iridodrilus Beddard and Segunia Sims (Annelida: Oligochaeta: Eudrilidae)

Abstract

This paper describes two new earthworm species, Iridodrilus codonothecoformis sp. n. and Iridodrilus condylopapillaris sp. n. and illustrates the major diagnostic features of, and the differences between, Iridodrilus roseus Beddard, 1897 and Heliodrilus lagosensis Beddard, 1890. Hitherto unnoticed features of I. roseus are also illustrated, namely that it possesses a bursa copulatrix and that two pairs of very tiny penial setae in sacs occasionally occur which penetrate the bursa copulatrix. It is also demonstrated that the structures hitherto regarded as a ‘coelomic duct’ that supposedly links the two fertilization chambers is in fact a pair of ovarian ducts that lead from the paired ovaries to the chambers; these ducts are not interlinked. It is further argued that neither Iridodrilus roseus nor Heliodrilus lagosensis can be regarded as having a spermathecal system that is paired internally. The implications of these findings are discussed in relation to the taxonomy of the two named genera. It is recommended that Iridodrilus and Heliodrilus be regarded as valid genera s.s. Beddard, though with modified diagnoses.

Keywords :

• Annelida
• Oligochaeta
• Eudrilidae
• Soil fauna
• Nigeria
• Ethiopian Region