Marionina colpites

MARIONINA COLPITES (STEPHENSON, 1932)

(FIG. 4D–F)

Enchytraeus colpites Stephenson, 1932: 260–263, figs 12–13.

Lumbricillus colpites – Nielsen & Christensen, 1959: 96.

Type material: BMNH 1933.2.23.885–892, eight mature sectioned specimens (studied). Syntypes. Loc. Shore of Bay of Isles, South Georgia Leg. ‘ Discovery’ 1925–1927 (Stephenson, 1932).

Type locality: Shore of Bay of Isles, South Georgia Island.

Additions to Stephenson’s original description: Chaetae ~110 µm long. Epidermis covered with rows of pale gland cells, and with a few rows of deeply staining granular gland cells, latter rows aggregated anterior and posterior to chaetae (see M. fusca below). Dorsal vessel with peristomial bifurcation. Nephridia in 7/8– 10/11 and postclitellar segments. Ventral nerve cord with large subbuccal bulb; see Marionina discussion above. Sperm funnels ≥ 900 µm long, 230 µm wide. Spermathecae (Fig. 4E, F) ≥ 600 µm long, 60 µm wide at duct, 180 µm wide at ampulla, with glands 55–100 µm wide surrounding pore.

Remarks: Stephenson was uncertain whether to place this species in Lumbricillus or Enchytraeus Henle, 1837 (and apparently did not consider Marionina), and decided pro Enchytraeus because of the lack of lobed testis sacs and absence of defined penial bulb. The testes are indeed small but do appear partly lobed; we could not make out whether the mass of developing cells was fully enveloped in testis sacs or distally free, but the mass is enveloped in a seminal vesicle as it bulges into anterior segments. The male apparatus, with its separate glands that discharge independently around the male pore, is similar to that described for M. benhami.