Geogenia namaensis (Michaelsen, 1908)

Plisko, Jadwiga Danuta, 2009, Pre-testical spermathecal pores and unusual setal arrangement in the South African endemic microchaetid earthworms of presumed Gondwanan origin (Oligochaeta: Microchaetidae), African Invertebrates 50 (2), pp. 237-237 : 246-248

Geogenia namaensis (Michaelsen, 1908)

Microchaetus namaensis: Michaelsen 1908: 40 ; 1918: 319; Reynolds & Cook 1976: 143; Plisko 1992: 339;

1995: 48 [redescription]. Geogenia namaensis: Plisko 2006: 44 . Type locality: South Africa: Northern Cape, Komaggas, Namaqualand (29 ° 48'S: 17 ° 30'E). Species type locality given by Michaelsen is ‘Klein-Namaland, Kamaggas’ .

The absence of spermathecae, reported in the species description by Michaelsen (1908), obscured its relationship with other microchaetids known at that time. Plisko

(1995), re-examining type material, found spermathecae, although small, in segments 10, 11, 12, with their ducts close to intersegmental furrows 9/10, 10/11, 11/12. The location of spermathecae in the testicular segments, with one pair of pores anterior to the testes, is unique in holandric species, and to date it has been observed only in this species, and in two species of Geogenia and one of Tritogenia , which are also discussed in this paper. The arrangement of setae described by Michaelsen and confirmed by myself does not reveal any irregularities in the clitellar area.

This species obviously differs from the proandric species accredited to the lesothoensis species-group in being holandric, with setae arranged in four regular rows and no discrepancy in the arrangement. The location of spermathecae and their pores is unique, with the anterior pair in furrow 9/10.

Not much is known about the species’ type locality, other than that it was found in the northern part of Namaqualand. From the data given for the other species mentioned in the species description, it might be concluded that namaensis was found together with the introduced Microscolex phosphoreus (Dugès, 1837) and Aporrectodea caliginosa (Savigny, 1826) , possibly in a newly created garden, or introduced from some other site.

As only the type material is known, and no new specimens have been found in the type locality area or other parts of South Africa, it is difficult to speculate on its relationship with its congeners .