Dichogaster sp. B

James, Samuel W. & Divina, Gildas Brice, 2012, Earthworms (Clitellata: Acanthodrilidae, Almidae, Eudrilidae, Glossoscolecidae, Ocnerodrilidae) of the coastal region of Gamba, Ogooué-Maritime Province, southwestern Gabon, Zootaxa 3458, pp. 133-148 : 142

? Dichogaster sp. B

Material. USNM 1180246 , juvenile, Falaise de Véra , Gamba Complex, Gabon under log on forested hillside at 2.84873°S, 10.23569°E, 22 m asl., 16 May 2008; S. James, G. Divina, G. Moussavou and L. Tchignoumba, colls .

Description. Unpigmented, 80 mm long, first dorsal pore 12/13; male field with prostatic pores in XVII, XIX; the latter less developed. Prostomium separated from peristomium dorsally by invaginated ring having the appearance of deep segmental boundary but clearly not a boundary; prolobous otherwise. Weakly muscular proventriculus in V, strong gizzards in VI, VII; anterior septa 10/11–13/14 muscular, other anterior septa membranous. Reniform calciferous glands paired XV–XVII, lamellar internal structure. Intestinal origin XIX, intestinal pouches small paired knobs on dorsal intestine XXIX–XXXV; typhlosolar origin 26/27, full size by XXXI, complex with regularly paired vertical flaps; lateral typhlosoles very small ridges XXVII–XXXV. Nephridia sac-form, 16 per segment. Spermathecae VII, IX, short duct, bulbous ectal portion of ampulla with stalked multi-locular diverticulum at duct junction; main ampulla clavate. Prostates of XVII long folded tubule confined to XVII, prostates of XIX much smaller, both with muscular ducts but those of XVII much larger. Large penial setal follicles in XVII only, penial setae long, hair-like with undulating ectal portion tapering to a fine point bent in a 90° curve.

Remarks. We were considering placing this worm in Millsonia Beddard, 1894 following the taxonomy of Csuzdi (1996b, 2010), but the intestinal pouches are of a different form and are probably not homologous to the digitate caeca of Millsonia. Following that interpretation, the presence of gizzards in VI and VII, the complex typhlosolar structure and the form of the penial setae also support placement of this worm in Dichogaster (Dichogaster) . The complex typhlosolar structure and the undulating penial setae with a 90° curve at the tip are also found in Dichogaster gambaensis , Dichogaster sp. C and Dichogaster sp. A . These other species have gizzards in V and VI. Species with intestinal pouches are known to occur in some Eutrigaster (following Csuzdi (1996b), or Dichogaster , as was advocated in James (1996, 2004)) from Guadeloupe and Jamaica. With now two known potentially independent evolutions of dorsal pouches within Dichogaster and Eutrigaster and the separate origin of digitate caeca in Millsonia, it is necessary to be careful with interpretation and assignment to genera or species groups.