Proandricus zeugosus, Plisko, 2005

Plisko, Jadwiga Danuta, 2005, Five new South African earthworm species of the family Microchaetidae (Oligochaeta) with exceptional anatomical features, African Invertebrates 46, pp. 103-113 : 110-111

Proandricus zeugosus sp. n.

Figs 6, 7

Etymology: Gr. zeugos (a team, pair). Refers to the paired spermathecae observed in this species.

Description:

External features: Body cylindrical. In life dorsally violet-grey; yellowish-grey after preservation in alcohol for more than ten years. Holotype when preserved 52+ mm long, 4 mm at 10 and 5 mm at clitellum; aclitellate paratypes when preserved 26–72 mm long, 3 mm wide. Segment number: holotype abscised 120+, aclitellate paratype 202. Prostomium: prolobous, small. Segmentation: secondary annulation present on preclitellar segments; 1 and 2 short, with irregular longitudinal grooves; 3 simple, longer than segment 1 or 2; 4–8 with 2 simple ringlets similar in size and appearance; 9 with 2 ringlets, second shorter than first; 10 and 11 simple, short; clitellar segments dorsally and ventrally with irregular annulation. Setae: closely paired, minute; first pairs on 3. Nephridial pores: first pair in intersegmental furrow 3/4. Female pores: in anterior part of segment 14, between a–a setae. Male pores: in intersegmental furrow 17/18, in area of tubercula pubertatis, in small invaginations. Spermathecal pores: in two intersegmental furrows 11/12 and 12/13, dorso-laterally.

Clitellar region ( Fig. 6 ): Clitellum: saddle-shaped, well developed, segmented, on 11–21; on 11 and 21 thinner layer of clitellar tissues; lateral borders parallel with cd setal lines; separated from tubercula pubertatis by narrow grooves. Tubercula pubertatis: on 1/n14–18; flat glandular bands, rounded at corners, segmented, detached from clitellum by narrow grooves; ventrally extended to b setae. Papillae: on 16–19; tiny swellings below tubercula pubertatis; paired, linked with ab setae.

Internal characters: Septa: 4/5 slightly thickened, 5/6 and 6/7 not thickened, very thin; 7/8 and 8/9 thickened more than 4/5, both muscular, firm, similar in size and appearance; other septa thin. Gizzard: in 7, small; barrel-shaped, anteriorly muscular; posteriorly softened. Calciferous glands: in 9, separated dorsally and ventrally. Intestine: commences in 12. Typhlosole: commences probably in 19, U-shaped, large. Dorsal blood vessel: in segments 4–6 double, separated, in 7 anteriorly simple, posteriorly double, separated; in 8 double, separated; in 9 cordiform; simple, when crossing septa, in 10 and the following segments. Paired dorsoventral vessels: 4–7 simple, thin, 8 slightly enlarged, 9–11 enlarged, moniliform. Nephridia : holonephridia, one pair per segment; coiled loops with elongated, multi-folded caeca. Male funnels: proandric arrangement; one pair in 10, of large funnels enclosed in sac, closely connected to seminal sacs. Vasa deferentia: not observed due to contracted segments in this area of body. Seminal vesicles: one pair of large sacs, anteriorly connected with sac of male funnels at 10/11, extending to 11. Spermathecae: in 11 and 12, close to intersegmental furrows 11/12 and 12/13; in 11 one pair of small, elongated, simple ampullae; in segment 12 at its left side, closely joined twin-ampullae; at right side double twin-ampullae ( Fig. 7 ). Ovaries: not observed. Genital glands: paired; in segments 12 and 13 very small, circular, flat; in 15 much larger, flat, glandular.

Comparison and comments: This species, having spermathecal pores in intersegmental furrows 11/12 and 12/13 and three variably thickened septa 4/5, 7/8 and 8/9, may be, with reservation, allocated to the belli species-group. However, P. zeugosus differs from other congeners in the shape of its spermathecae, commencement of the intestine, and very specific shape of its nephridia.

Holotype: clitellate, NMSA /Olig.01192: Eastern Cape: Cradock area, Mountain Zebra National Park (32º08'S: 25º38'E), alt. approx. 1800 m, near local stream, 5.xii.1991, J.D. Plisko & A. Zicsi.

Paratypes: NMSA /Olig.01147, 6 aclitellate specimens collected together with holotype .

Biological notes and distribution: This species was collected at the entrance to the Mountain Zebra National Park , near a small stream, in moist soil between roots of various plants. It is known only from the type locality in the Eastern Cape .

Figures

Figs 5–8. (5) Proandricus notabilis sp. n., holotype, lateral part of clitellum and tuberculum pubertatis, 60 X; (6, 7) Proandricus zeugosus sp. n., holotype: (6) anterior part of body, laterally, 60 X, (7) spermathecae of segment 12, 140 X; (8) Tritogenia phinda sp. n. holotype, clitellar region, ventral view, 60 X. Abbreviations: C–clitellum, T–tuberculum pubertatis, P–papilla of segment 25, Sp–spermathecae.