Olavius paraloisae, 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 : 48-49

Olavius paraloisae sp. nov.

Figure 1

Material examined

Holotype: SMNH Type Coll. 6363, whole­mounted specimen.

Type locality: New Caledonia, Loyalty Islands, Lifou, Baie du Santal, 3 m (station NC00­26).

Paratypes: SMNH Type Coll. 6364­6372, 9 specimens: 2 from type locality, 1 from each of stations NC00­29, NC00­45, NC00­8 and NC00­10, and 3 from NC00­35.

Other material: SMNH Main Coll. 85036–85066, 31 specimens: 5 from each of type locality and NC00­ 28, 1 from each of NC00­8, NC00­19 and NC00­44, 2 from NC00­46, 3 from each of NC00­10, NC00­29, NC00­39 and NC00­45, and 4 from NC00­35.

Description

Length 2.5–10 mm, with 22–75 segments. Width at XI, 0.13–0.19 mm. Body cylindrical. Prostomium rounded. Pygidium variable, with rounded tip. Clitellum extending over 2/ 3X –2/ 3XII. Secondary annuli generally 7 per (postclitellar) segment. Somatic chaetae ( Fig. 1 A) bifid, with upper teeth thinner and shorter than lower, and each with conspicuous subdental ligament. Bifids 36–41 m long, about 2 m thick, (2) 3 per bundle in anterior segments, 2 per bundle in postclitellar segments, absent in segment XI. Penial chaetae absent. Spermathecal pores paired, located in line with ventral somatic chaetae, anteriorly in X. Male pores paired, located more or less in line with ventral chaetae, in posterior part of XI.

Male and female genitalia ( Fig. 1 B) paired. Vas deferens thin but muscular, 7 m wide for most parts, longer than atrium, coiled, gradually widening into atrium, cilia not observed but probably present inside. Atrium elongated oval, 80–112 m long, about 33–55 m wide, with thin indistinct muscular layer, and granulated inner epithelium, but cilia not observed on latter, lumen narrow. Prostate glands absent. Atrium opening into inner end of a small, complex copulatory sac with heavily folded wall; this sac communicating with exterior through small (male) pore (pore not shown in Fig. 1 B, as it is hidden under copulatory sac). Spermathecae ( Fig. 1 B, s) oval­shaped, walls irregular, totally 80–96 m long, 26–39 m wide, with short ducts that are not well set off from ampullae. Each spermatheca with somewhat bundled sperm.

Etymology

Named Olavius paraloisae for its resemblance to O. loisae Erséus, 1984 .

Remarks

This species is closely related to Olavius loisae Erséus, 1984 , from the Great Barrier Reef, although it is separated from that species by its more elongated atria but less slender spermathecae. The atria of O. loisae are about 1.3–1.6 times longer than wide, while those of O. paraloisae are up to about 2.5 times longer than wide. Moreover, in O. loisae , a demarcated, narrow duct makes up about 1/3 of the total length of each spermatheca (see Erséus 1984, fig. 29), whereas in O. paraloisae , virtually the whole spermatheca appears to be a continuous ampulla, and the spermathecal duct is short and indistinct ( Fig. 1 B)..

Distribution and habitat

New Caledonia (Loyalty Islands). Subtidal, more or less heterogeneous sand, 2–22 m depth.

Figures

FIGURE 1. Olavius paraloisae sp. nov. A) free­hand drawing of somatic chaeta, B) somewhat horizontal view of spermatheca and male genitalia in segments X – XI.