Dichogaster (Diplothecodrilus) moussavoui, James & Divina, 2012

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 : 134

Dichogaster (Diplothecodrilus) moussavoui sp. nov.

( Figs 1A,B, 3A)

Material. Holotype USNM 1142292 , semi-clitellate, Falaise de Véra , Gamba Complex, Gabon 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.; paratype USNM 1142293 , semi-clitellate head fragment, same data as holotype.

Etymology. This species is named after Gautier Moussavou, one of the Gabon Biodiversity Program technicians who were part of the collecting team at Gamba.

Diagnosis. Dichogaster (Diplothecodrilus) with eight nephridia per segment, free testes and funnels, acanthodriline male field, and penial setae with protruding teeth and a partially twisted lanceolate tip.

Description. Dimensions 25 mm by 1.6 mm at segment X, 2.0 mm at clitellum (not developed), 2.0 mm at XXX; body cylindrical throughout, segments 101. Setae closely paired throughout; setal formula AA:AB:BC:CD = 4:1:3:1 at X, 6:1:5:1 at XXX, DD> 1/2 circumference throughout. Prostomium prolobous, no secondary annulation. Pale red-brown pigmentation on peritoneum. First dorsal pore 5/6, spermathecal pores paired 7/8/ 9 in AB ahead of small protuberances. Ovipores nearly equatorial just median to A in XIV; male pores in XVIII; prostatic pores and penial setae at ends of seminal grooves in AB in XVII–XIX. Seminal grooves straight or slightly convex laterally, narrow midventral genital marking on 8/9 between spermathecal pores ( Fig. 1A).

Septa 5/6–7/8 membranous, 8/9–11/12 are transparent with some muscle fibers. Alimentary canal with two gizzards in V, VI; separated by thin annulus; paired calciferous glands in XV–XVII, reniform with internal lamellar structure; glands of XV smaller than those of XVI, XVII, which are roughly equal; glands with separate ducts to esophagus wall, but close together; esophagus valvular in XVIII, intestinal origin XIX; typhlosole a thick undulating fold originating in XXIII, height less than one fourth lumen diameter, ending in LXXXIII. No lateral typhlosoles. Nephridia of anterior segments small plectonephridia, 8 per segment; in intestinal segments stomate megameronephridia 1 pair near AB, 6 sac-like meronephridia per segment from B to above D.

Vascular system with ventral trunk, single dorsal trunk, these connected by lateral trunks in VII–IX, lateroesophageal hearts in X–XII. Extra-esophageal vessel not seen; supra-esophageal vessel X–XII.

Ovaries, funnels free in XIII; paired spermathecae in VIII, IX, ampulla in two parts, an ectal barrel-shaped section and a thinner-walled ental lenticular chamber; simple shortly stalked iridescent diverticulum attached at the base of the ampulla’s ectal chamber; long slender, slightly muscular duct longer than ampulla ( Fig. 1B).

Male sexual system holandric, testes, funnels free in X,XI; seminal vesicles in XI, XII; vasa deferentia superficial, enter body wall in XVIII; tubular prostates XVII, XIX in one or two short kinks, confined to segments of origin; slender muscular ducts; penial setal follicles joined to body wall by long dorsal muscle band reaching to middorsal. Penial setae bowed, the ectal part of the curve tightens slightly, followed by recurved ectal quarter with 7–9 triangular teeth protruding slightly from the convex side of the recurve; comparable number of small teeth flat on the opposite side, 0.83 mm long, diameter 28 µm in basal two thirds. Just after the teeth the seta bends back the other way, flattens to become lanceolate in overall outline, and has a partial twist ( Fig. 3A).

Remarks. By the location of the first dorsal pore and the spermathecal ampulla’s differentiation into two sections, this species belongs to subgenus Dichogaster (Diplothecodrilus) Csuzdi, 1996 . Within that subgenus Csuzdi (1996b) indicates six species-groups with a single type of penial setae and divides them according to the general form of the penial setae. Of the general forms the congica -group is closest in having one or more large teeth below the tip. Within that group of 18 species the present species is closest to D. gabunensis Michaelsen, 1915. D. gabunensis differs from the new species in free testes and funnels, the more clearly bipartite spermathecal ampulla, lack of teeth on the penial setal lanceolate tip, and overall greater number of teeth on each side of the penial setae. Besides this, it is diagnosed by the combination of having 8 nephridia per segment, free testes and funnels, acanthodriline male field, and penial setae with protruding teeth and a partially twisted lanceolate tip.