Grania fiscellata, Wit, Pierre De & Erséus, Christer, 2007

Wit, Pierre De & Erséus, Christer, 2007, Seven new species of Grania (Annelida: Clitellata: Enchytraeidae) from New Caledonia, South Pacific Ocean, Zootaxa 1426, pp. 27-50 : 45-47

Grania fiscellata sp.n.

( Figure 9 , Table 1)

Holotype: SMNH type coll. 6610, whole-mounted (incomplete) specimen from Touho, stn. NC93-66.

Paratypes: SMNH type coll. 6611-6613, 3 mounted specimens (2 of which are incomplete) from Touho, stn. NC93-25; SMNH type coll. 6617, whole-mounted specimen from Lifou, stn. NC00-36.

Description: Body 3.4 mm long (n=1), 0.11–0.12 mm wide at III, 0.10–0.12 mm at clitellum (n=3). Segment number 42 in the only complete specimen. Prostomium rounded, 55–65 μm wide, 35–45 μm long (n=3); epidermis 8–20 μm thick on occipital lobes and upper lip, 5–10 μm at front side (n=3). Peristomium 90–100 μm wide at 1/2 (n=3). Ventral chaetae commencing in IV; lateral chaetae commencing in XIV–XV. Chaetae of uniform size throughout body, 40–45 μm long (n=4); chaetae sharply pointed, entally curved into a hook 8–10 μm long ( Figure 9 A). Epidermal gland cells inconspicuous, interspersed irregularly. Clitellum 15–25 μm thick, starting at anterior of XII and extending to chaetal position of XIII, consisting of transverse rows of granular gland cells interspersed with hyaline cells at a ratio of about 4:1 ( Figure 9 B), except around male pores where hyaline cells are absent. “Copulatory glands” not observed in XIV. Spermathecal pores lateral, located right behind 4/5. Male pores located ventrolaterally in mid XII.

Brain in II–III, posteriorly indented in “head” region. Head organ absent. Pharyngeal glands located from 4/5 to 6/7, not united dorsally; dorsal lobes present in IV–VI, ventral lobes present in V (2 pairs) and VI (2 pairs); no ventral lobes in IV ( Figure 9 C). First pair of nephridia at 7/8. Dorsal blood vessel commencing in XVI (visible in one specimen only). Chloragogen cells small (5–7 μm tall). Coelomocytes abundant, slightly oval, flattened, granular with irregular surface, about 10 μm wide at the widest point. Sperm sac extending posteriorly to XIII or XIV. Sperm funnels of uniform width, 15–25 μm, 3–4 times as long as wide. Heads of spermatozoa about 8–10 μm long. Vasa deferentia in XII, strongly muscularized entally, 6–7 μm wide. Penial apparati ( Figure 9 D) consisting of a glandular widening of the most ectal end of vas deferens (diameter 9–10 μm), which is curved around, and attached to, a small aglandular invagination of epidermal tissue from male pore, 20–30 μm deep, 5–10 μm wide (Penial bulb type 6, without stylet). Stylets absent. Egg sac extending as far back as XIX. Spermathecal ectal ducts bulbous, about 15 μm wide at widest point, projecting slightly into ampullae, ampullae pear-shaped, 20-25 μm wide, 25–30 μm long, connected to gut in middle of V, sperm existing in ampullae both in loose form in the lumen and as small sperm rings embedded in walls, 3–5 μm in diameter; ectal glands on spermathecal ducts absent ( Figure 9 E).

Etymology: Fiscella is a Latin word for a small basket, and – ata translates into “equipped with”, indicating that this species indeed is equipped with a small basket, i.e. spermatheca.

Remarks: A spermathecal connection to the gut in mid V is unusual in Grania . It has hitherto been described in 7 species, which include a few species from Hong Kong ( G. hongkongensis Erséus, 1990 , G. i n e r - mis Erséus, 1990 and G. stilifera Erséus, 1990 ) and also, interestingly enough, G. m i r a Locke & Coates, 1998 (see below).

The male genital system of G. fiscellata is different from that of most other species of Grania in that it has a thick and muscularized vas deferens and a reduced gland at the male pore, yet it bears no stylet. Thus, the penial apparatus of this species does not fit any of the penial bulb types defined by Coates (1984). Some muscular modifications of the vas deferens in conjunction with a penial bulb of this shape has been described in several species, e.g. G. m i r a, G. canaria Rota & Erséus, 2003 , G. fortunata Rota & Erséus, 2003 and G. aquitana Rota & Erséus, 2003 , but G. m i r a, an Irish taxon, is the only species with vasa deferentia that are muscularized throughout as well as small epidermal invaginations, and at the same time the species lacks penial stylets.

The peculiar widening of the vas deferens forming a curved structure around the male pore resembles a glandular penial bulb in low magnification; the vas deferens is rather coiled which makes it very difficult to follow. However, at high magnification it becomes clear that the vas deferens is glandular while a separate glandular bulb is absent, which to date is a feature unique to G. fiscellata .

Distribution and habitat: Touho area, New Caledonia, and Lifou, Loyalty Islands, lower intertidal and shallow subtidal (3 m), heterogeneous sand.

Figures

FIGURE 9. Grania fiscellata sp. n.. A: Chaetae. B: Clitellar cell pattern. C: Overview of I – VII. D: Penial apparatus. E: Spermatheca.