Olavius lifouensis, Erséus, Christer & Bergfeldt, Ulrika, 2007

Erséus, Christer & Bergfeldt, Ulrika, 2007, Six new species of the gutless genus Olavius (Annelida: Clitellata: Tubificidae) from New Caledonia, Zootaxa 1400, pp. 45-58 : 54-55

Olavius lifouensis sp. nov.

Figure 5

Material examined

Holotype: SMNH Type Coll. 6394, whole­mounted specimen. Type locality: New Caledonia, Loyalty Islands, Lifou, Baie du Santal, 3 m (Station NC00­36). Paratypes: SMNH Type Coll. 6395–6399, 5 specimens: 2 from each of NC00­5 and NC00­8, and 1 from NC00­19.

Description

Length more than 6–7 mm, with more than about 50 segments; one individual with regenerating posterior end shorter than this, but all other specimens incomplete. Width at XI, 0.25–0.30 mm. Body cylindrical. Prostomium rounded. Pygidium rounded. Clitellum extending over X­XII. Secondary annuli 3–5 per (postclitellar) segment. Somatic chaetae ( Fig. 5 A) bifid, with upper teeth thinner and shorter than lower, and each with conspicuous subdental ligament. These chaetae 48–60 m long, about 2.5–3 m thick, 2 per bundle throughout body. Penial chaetae ( Figs. 5 B; 5C, pc), 50–65 m long, about 2.5 m thick, 5–6 per bundle, straight and parallel, with single­pointed and strongly curved tips. Spermathecal pores paired, located in line with dorsal chaetae, anteriorly in X. Male pores paired, located in line with ventral chaetae, in posterior part of XI.

Male and female genitalia ( Fig. 5 C) paired. Vas deferens not muscular, about 10 m wide for most parts, longer than atrium, coiled, cilia not observed but probably present inside. Atrium 75–85 m long, 24–36 m wide, with thin indistinct muscular layer, and granulated inner epithelium, but cilia not observed on latter, lumen narrow. Outer end of atrium modified to a narrow duct­like part. Two, somewhat lobed, prostate glands present, one located anterior to and attached to ental part of atrium, other located posterior to and attached to ectal end of atrium by stalk. Atrium opening into inner end of complex copulatory sac with heavily folded wall; this sac communicating with exterior through small (male) pore (pore not shown in Fig. 5 C, as it is hidden under copulatory sac). Spermathecae ( Fig. 5 C, s) slender, totally 120–135 m long, 24–27 m wide, with short, narrow, but obvious ducts well set off from thin­walled ampullae. Each spermatheca contains bundle of sperm.

Etymology

Named Olavius lifouensis after Lifou Island where it was discovered.

Remarks

Olavius lifouensis is in many ways similar to O. patriciae Erséus, 1993 , from Rottnest Island, Western Australia. The general body size, the shape of the atria, the deeply folded copulatory sacs without papilla, the very slender spermathecae and the several, rather small penial chaetae, are all features that are shared by the two species. However, they differ in the location of the spermathecal pores (those of O. patriciae are located in the lateral lines), the number of secondary annuli, which are unusually few in O. lifouensis (but mostly 7 per segment in O. patriciae ), and the number of somatic chaetae (up to 4 per bundle anteriorly, and up to 3 per bundle in postclitellar segments in O. patriciae ). Olavius lifouensis also appears closely related to the (much larger) species, O. nivalis sp. nov. (see Remarks for latter below).

Distribution and habitat

New Caledonia (Loyalty Islands). Subtidal, more or less heterogeneous sand, 2–18 m depth.

Figures

FIGURE 5. Olavius lifouensis sp. nov. A) somatic chaeta, B) free­hand drawing of penial chaeta, C) oblique view of spermatheca and male genitalia in X – XI.