Olavius fidelis, 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 : 52-53

publication ID

https://doi.org/ 10.5281/zenodo.175403

DOI

https://doi.org/10.5281/zenodo.5667334

persistent identifier

https://treatment.plazi.org/id/8467A05A-FFB6-C33F-78E6-699FFA2CF85F

treatment provided by

Plazi

scientific name

Olavius fidelis
status

sp. nov.

Olavius fidelis sp. nov.

Figure 4 View FIGURE 4

Material examined

Holotype: SMNH Type Coll. 6390, whole­mounted specimen. Type locality: New Caledonia, Loyalty Islands, W side of Lifou, 31 m (Station NC00­22). Paratypes: SMNH Type Coll. 6391–6393, 3 specimens from type locality. Other material: SMNH Main Coll. 85112–85124, 13 specimens: 5 from type locality, 1 from NC00­8, 2

from NC00­3, and 5 from NC00­36.

Description

Length up to at least 3.4 mm, with up to at least about 30 segments; several specimens amputated. Width at XI, 0.15–0.23 mm. Body cylindrical. Prostomium rounded, in most specimens somewhat longer than wide. Pygidium rounded. Clitellum extending over 1/ 2X –1/ 2XII. Secondary annuli 8–14 per (postclitellar) segment. Somatic chaetae ( Fig. 4 View FIGURE 4 A), bifid, with upper teeth thinner and shorter than lower, and each with conspicuous subdental ligament. These chaetae 25–35 m long, about 1–2 m thick, 2 per bundle throughout body; but totally absent in segment XI. Penial chaetae ( Fig. 4 View FIGURE 4 B), 20–35 m long, about 1.2 m thick, 6–10 per bundle, straight, with single­pointed and strongly curved tips; chaetae not strictly parallel within bundle, but forming a somewhat arched row. Spermathecal pores paired, in lateral lines, anteriorly in X. Male pores paired, located more or less in line with ventral chaetae, in posterior part of XI; each pore is a rather conspicuous C­shaped slit ( Fig. 4 View FIGURE 4 C, mp), along the convex side of which the row of penial chaetae can be seen ( Fig. 4 View FIGURE 4 C, pc).

Male and female genitalia ( Fig. 4 View FIGURE 4 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 small, round, about 35 m long, 24–31 m wide, with thin indistinct muscular layer, and granulated, compartmented inner epithelium, but cilia not observed on latter, lumen narrow. Two large, 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 small copulatory sac, latter with folded wall that may form a distinct papilla (pa); copulatory sac communicating with exterior through (male) pore ( Fig. 4 View FIGURE 4 C, mp). Spermathecae ( Fig. 4 View FIGURE 4 C, s) slender, totally 86–96 m long, with narrow ducts clearly set off from thin­walled, 17– 24 m wide, ampullae. Spermathecal vestibules may be present, but not obvious. Each spermathecal ampulla with a bundle of sperm.

Etymology

Named Olavius fidelis (Latin for loyal), for the Loyalty Islands where it was discovered.

Remarks

Olavius fidelis shares a unique combination of characters with three species from the Indian Ocean, O. manifae Erséus, 1986 ( Saudi Arabia), O. abrolhosensis Erséus, 1997 (Houtman Abrolhos Islands, Western Australia), and O. hamulatus Erséus, 1997 (Montebello Islands, Western Australia). All four species have bichaetal (somatic) bundles throughout the body, numerous small penial chaetae, small oval atria, copulatory sacs with folded walls, and slender spermathecae. The main distinguishing features are summarized in Table 2 View TABLE 2 . The new species appears most closely related to O. abrolhosensis , but differs from this species by its lack of muscles around the spermathecal vestibules.

In this species (as well as O. abrolhosensis ), the number of secondary annuli varies, but tend to be twice the number common in most other gutless species.

Distribution and habitat

New Caledonia (Loyalty Islands). Subtidal sand, 0.5–31 m depth.

Spermathecal vestibules if present, not obvious obvious, muscular if present, not obvious if present, not obvious

TABLE 2. Morphological comparison between four closely related, Indo­West Pacific, forms of Olavius.

Secondary body annuli 7 per segment 7–14 per segment 6–7 per segment 8–14 per segment
Penial chaetae (length) about 7–9 per bundle (about 25 µm) about 6 per bundle (about 25 µm) about 6 per bundle (about 25 µm) 6–10 per bundle (20–35 µm)
Spermathecal pores latero­dorsal mid­lateral latero­ventral mid­ventral
Atrial length about 40 µm about 35 µm about 95 µm about 35 µm
SMNH

Saskatchewan Museum of Natural History

Kingdom

Animalia

Phylum

Annelida

Class

Clitellata

Order

Haplotaxida

Family

Tubificidae

Genus

Olavius

Loc

Olavius fidelis

Erséus, Christer & Bergfeldt, Ulrika 2007
2007
Loc

O . abrolhosensis Erséus, 1997

Erseus 1997
1997
Loc

O . hamulatus Erséus, 1997

Erseus 1997
1997
Loc

O . manifae Erséus, 1986

Erseus 1986
1986
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