Some new species of Haplotaxidae (Oligochaeta) from Guinea and remarks on the history of the family

Abstract

Three new species of Haplotaxidae collected by Dr. A. Villiers in a cave near Kindia, Guinea, are described. One species belongs to the genus Metataxis Righi, 1985 (M. carnivorus sp. nov.) which is distributed in Western Africa and Eastern America. Another new species is similar to Lycodrilus kraepelini Michaelsen, 1914 incertae sedis: a new genus Villiersia is proposed for both species ( K guanivora sp. nov., K kraepelini nov. comb.).A third species, of which only immature specimens are available, is tentatively attributed to the genus Haplotaxis: it is remarkable because of its peculiar setae and commissural vessels (H. villiersi sp. nov.).The three species appear to feed on bat guano and, occasionally, on aquatic arthropods. Metataxis, Tiguassu and Villiersia belong to the section of Haplotaxidae endowed with paired sperm sacs and ovisacs.The relations of Haplotaxidae with other families are discussed and it is suggested that the passage from the haplotaxid condition to that of sparganophilids and more advanced lumbriciforms is connected to a change of reproductive strategy and to an enhanced metabolism.Haplotaxis villiersi sp. nov. Fig. 2. Haplotaxis carnivorus, Omodeo, 1958 (nom. nud.).Cave of Sigea, near Kindia, Guinea, in a brook; water pH 5.0, temperature 26 "C. Dr. A. Villiers leg. April 7,1954. Three young specimens well preserved. External morphologyBody slender, cylindrical 64-82 x 0.55 -0.66 mm.Segments without secondary annulation, amounting to 219, 225, 257. No cutaneous pigment, body wall transparent. Prostomium zygolobic with oval

Evolution and biogeography of megadriles (Annelida, Clitellata)

“…For many reasons such an alternative is less cogent. It does not fit the geographical distribution of the taxa invol- Righi, 1985 Metataxis bare Righi, 1988 Villiersia guanivora Omodeo, 1987 Fig. 13 -Three haplotaxid species showing structures which are perhaps homologues of the pubertal (or clitellar) ridges of Lumbricoidea.…”

“…In megadriles, a growth in body size cannot be matched by a proportional increase of the yolk reserves (Omodeo, 1987;Jamieson, 1988). Indeed, beyond a certain egg size, problems arise with regard to ooplasm elasticity and plasticity, egg laying, egg gas exchange, and even as a consequence of the energy waste occurring every time a ripe egg cannot be laid in due time.…”

“…Stephenson (1930) rejected this idea, which however was to be widely accepted afterwards (Brinkhurst, 1966(Brinkhurst, , 1984(Brinkhurst, , 1988Brinkhurst & Jamieson, 1971;Omodeo, 1987). In the case of the Lumbricoidea, this hypothesis appears -from a morphological and comparative point of view -the more plausible as the haplotaxids have spermathecae quite similar in form and position to those of Lumbricoidea, and three species show structures which appear homologous to the 'pubertal ridges' (Fig.…”

“…13 -Three haplotaxid species showing structures which are perhaps homologues of the pubertal (or clitellar) ridges of Lumbricoidea. Redrawn from Omodeo (1987) and Righi (1988Righi ( , 1995.…”

“…In recent years, the evolution and phylogeny of nonhirudinean Clitellata have been investigated both by cladistic (Jamieson, 1978(Jamieson, , 1988Erséus, 1987Erséus, , 1990Coates, 1989;Brinkhurst, 1991Brinkhurst, , 1992Brinkhurst, , 1994 and by traditional comparative methods (Omodeo, 1987;Rota & Omodeo, 1992). The results obtained with the two different procedures were not consistent, but a more careful examination of some relevant biological and zoogeographical aspects hitherto disregarded may reduce the discrepancies and bring specialists closer to a common view of the history and relationships of the subclass.…”