A new genus of West African earthworm with notes on the identity of Iridodrilus Beddard, 1897 (Eudrilidae : Oligochaeta) R. W. Sims Department of Zoology, British Museum (Natural History), London SW7 5BD In 1897 Beddard described an earthworm found in soil received from Lagos which because it had fewer intestinal gizzards, three, compared with species of his monotypic genera Hyperiodrilus and Heliodrilus from the same region each with six intestinal gizzards, he recognized as a new genus and species, Iridodrilus roseus. His action was acceptable since although few earthworms with intestinal gizzards were known at that time, among groups with oesophageal gizzards, the number and location were considered to be of primary taxonomic significance. Consequently in the Eudrilinae (Michaelsen, 1900), species with six intestinal gizzards came to be assigned to Hyperiodrilus, with Heliodrilus being reduced to a synonym by page priority, while species with three intestinal gizzards were accommodated by Iridodrilus, for example the otherwise dissimilar species from the Cameroons, /. preussi Michaelsen, 1903. This simplistic solution obscured the true affinities of some of the included species and many years elapsed before further material was collected that led to a morphological re-examination and appraisal of affinities of the species. Evidence that the numbers of intestinal gizzards could vary within a genus came with the description of new species of Legonea by Sims (1964) and Clausen (1967), and of Hyperiodrilus by Sims (1965) and Clausen (1967). Next it was shown that the possession of the same number of intestinal gizzards did not necessarily constitute grounds for making two species congeneric. Series from the vicinity of Ibadan possessed six intestinal gizzards but were found to have a basically paired spermathecal system below, or alongside, the gut like that described in Heliodrilus lagosensis and unlike Hyperiodrilus africanus that has perioesophageal ducts uniting dorsally in a single supra-intestinal receptaculum seminis; thus Heliodrilus and Hyperiodrilus were separated (Sims, 1977). In my opinion a similar situation persists in the genus Iridodrilus caused by overemphasis of the criterion of the presence of three intestinal gizzards for the inclusion of a species in the genus. This practice has resulted in dissimilar taxa, the poorly described roseus Beddard and the well-defined preussi Michaelsen being placed together while more recently the situation has been further confused when a new species /. vomiensis was described together with a close ally /. tonyii that has four intestinal gizzards (Segun, 19770). Accordingly to obtain more detailed information on the morphology of the type species of the genus than originally provided by Beddard, the two syntypes of /. roseus (BM(NH) 1904.10.5.962) were re-examined. Parti Iridodrilus roseus Beddard, 1 897 Iridodrilus roseus Beddard, 1897. Proc. zool. Soc. Lond. 1897, p. 346. DESCRIPTION. External characters. Length 58, 76mm, diameter 3 mm. Segments 94, 143; tending towards a biannulate condition. Dorsal pores absent. Clitellum almost annular but with a pale midventral stripe where the ventral edges fail to meet, thus strictly the clitellum should be regarded as being saddle-shaped. Male pore single, midventral in furrow 17/18, seen as a boss-like porophore with a longitudinal slit. Penial setae absent. Female pores paired ventrally near the equator of segment xiv, located setal distance lab within setal lines aa. Spermathecal pore single, midventral in furrow 12/13, carried on a low but broad porophore extending j Nephridiopores paired between setal lines cd. Bull. Br. Mus. not. Hist. (Zool.) 48(1): 1 1-14 Issued 28 February 1985 11
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