Grania galbina Wit & Erséus, 2007, sp.n.

Grania galbina sp.n.

(Figure 4, Table 1)

Holotype: SMNH type coll. 6573, whole-mounted specimen from Lifou, stn. NC00-17.

Paratypes: SMNH type coll. 6574-6582, 9 whole-mounted specimens from Lifou, 5 of which from type locality, and 1 from each of stns. NC00-18, NC00-20, NC00-25 and NC00-27.

Other material examined: SMNH main coll. 87958-87978, 21 whole-mounted specimens from Lifou (stns. NC00-17, NC00-18, NC00-27); SMNH main coll. 87979, 1 specimen from CENTOB, collected off Nouméa, New Caledonia, during the Nouvelle Calédonie 78 excursion in 1978 (stn. NC78-26B).

Description of type specimens: Living specimens greenish yellow. Body 6.4–7.8 mm long (n=10), 0.16– 0.20 mm wide at III, 0.16–0.22 mm at clitellum (n=10). Segment number 51–56 (n=10). Prostomium rounded, 65–85 μm wide, 45–75 μm long (n=9); epidermis 13–23 μm thick on occipital lobes and upper lip (n=7), 8–18 μm thick at front side (n=10). Peristomium 125–145 μm wide at 1/2 (n=10). Ventral chaetae commencing in IV or V, absent in XII, laterals commencing in XVIII–XX. Chaetae larger post-clitellum, 43–50 μm long in preclitellar segments (n=5), 50–60 μm post-clitellarly (n=9); chaetae L-shaped, sharply pointed with distinct heel, foot 13–20 μm long (chaetal index=3.92, n=14, sd=0.66) (Figure 4 A). Epidermal gland cells inconspicuous, interspersed irregularly. Clitellum 10–20 μm thick, starting at anterior end of XII and extending to chaetal position in XIII, consisting of unevenly shaped transverse cell rows with granular gland cells and hyaline cells at a ratio of about 3:1 (Figure 4 B), except around male pores where hyaline cells are absent. “Copulatory glands” not observed in XIV. Spermathecal pores lateral, as far back as one quarter into V. Male pores ventrolateral 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 present in IV (Figure 4 C). First pair of nephridia at 7/8. Dorsal blood vessel generally commencing in XIX–XXII, in one specimen in XVII. Chloragogen cells small (5–7 μm tall). Coelomocytes not observed. Sperm sac extending posteriorly from clitellum as far back as XIX, in most specimens to XV or XVI. Sperm funnels 25–35 μm wide at collar, tapering to 15–25 μm wide at other end, 4–5 times as long as wide. Heads of spermatozoa about 15 μm long. Vasa deferentia long, unmodified, loosely coiled posteriorly from XII to XIV; 6 μm wide, internally ciliated. Penial apparati (Figure 4 D) with oval, uniform glandular structures, 120–155 μm long, 60–80 μm wide, extending through most of XII, surrounding epidermal invaginations at male pores, 20–30 μm in diameter, vasa deferentia opening into invaginations (Penial bulb type 2 or 3). Stylets absent. Egg sac extending as far back as XXI. Spermathecae (Figure 4 E) attached to oesophagus near 5/6; ampullae roughly pear-shaped, 40–45 μm wide, ectal ducts narrow, 50–60 μm long, 10–15 μm wide, incising ampullae slightly; 5–10 sperm rings per spermatheca, 13–18 μm in diameter, located throughout ampullae; ectal glands on spermathecal ducts absent.

Remarks: When alive, this species is discernable from other Grania species by its distinct coloration. Whereas most other members of this genus are translucent or whitish in color, this species is brightly greenish yellow; this could, however, be the case for some other species as well, considering that the coloration is lost after fixation.

A spermathecal pore location at some distance from 4/5 has been described for some 15 species of Grania to date, mostly Atlantic, but also Western Australian (G. vacivasa Coates & Stacey, 1993) and Antarctic taxa (G. algida Rota & Erséus, 1996; G. antarctica Rota & Erséus, 1996). Grania galbina differs from all of the above, however, in the possession of large glandular masses surrounding the male pores, structures which resemble those of G. postclitellochaeta (Knöllner, 1935) (see Coates, 1984), with the difference of having more conspicuous epidermal invaginations at the male pores. This is a morphology resembling that in G. f o r - tunata Rota & Erséus, 2003 and G. h y l a e Locke & Coates, 1999, both which are North Atlantic species. Grania hylae, however, possesses stylets, which is not the case in G. galbina. The spermathecal structure of G. galbina also resembles that of G. fortunata and G. h y l a e, but G. galbina differs from these two by its lack of a head organ and in the presence of a distinct heel at the base of the chaetae.

Etymology: From the Latin word galbinus, which translates into greenish yellow.

Distribution and habitat: Nouméa area, New Caledonia, and Lifou, Loyalty Islands, intertidal and subtidal (13 m), heterogeneous sand.