Grania breviductus Wit, Rota & Erséus, 2009, sp. n.
Creators: name: Wit, Pierre De
name: Rota, Emilia
name: Erséus, Christer
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Clitellata
Enchytraeida
Enchytraeidae
Grania
Grania breviductus

description: Grania breviductus sp. n.
(Figs. 2, 10 A)
Holotype: AMS type coll. W.35536, whole-mounted specimen from Heron Island, stn. H1.
Paratypes: AMS type coll. W.35537-W.35542, 6 whole-mounted specimens from Heron Island: 3 from stn. H1, 2 from stn. H8, and 1 from stn. H2. SMNH type coll. 7761-7766, 6 whole-mounted specimens from Heron Island, stn H8.
Description: Body 8.3–9.8 mm long (n=11), 0.11–0.18 mm wide at III, 0.11–0.15 mm at clitellum (n=13). Segment number 49–61 (n=11). Prostomium rounded, 65–90 µm wide, 40–60 µm long (n=13); epidermis 19–28 µm thick dorsally, 15–23 µm anteriorly (n=11), 9–19 µm ventrally (n=13). Peristomium 115–135 µm wide at 1/2 (n=13). Ventral chaetae commencing in VI, lateral chaetae commencing in XVIII–XX. Chaetae of uniform size throughout body, somewhat shorter laterally (45–60 µm) than ventrally (60–80 µm long (n=22); chaetae stout, of equal thickness in ental half, tapering ectally, L-shaped, entally bent into a narrow “foot” (10–17 µm) with an angle of about 100 degrees between shaft and foot; foot with low instep, moderate heel and curved sole, chaetal index =4.28, n=22, sd=0.610 (Figs. 2 A, 10A). Epidermal gland cells inconspicuous. Clitellum 9–22 µm thick, starting in anterior of XII and extending to mid XIII, with transverse rows of granular gland cells interspersed with hyaline cells at a frequency of about 1:1 (Fig. 2 B), except near male pores where hyaline cells are absent, and midventrally where gland cells are absent. Midventral copulatory gland observed in XIV. Spermathecal pores lateral, located immediately behind 4/5. Male pores located ventrolaterally in mid XII.
Brain posteriorly indented. Head organ absent. Pharyngeal glands in IV–VI; dorsal lobes present in IV–VI, ventral lobes present in V (2 pairs) and VI (2 pairs); not connected dorsally. First pair of nephridia at 7/8. Dorsal blood vessel commencing in XIX–XXVI. Chloragogen cells small (5–7 µm tall). Coelomocytes oval, about 8x15 µm, granular with unstained nucleus, only present in last 10–12 segments. Sperm sac extending posteriorly from clitellum as far back as XX. Sperm funnels of uniform width, 35–45 µm wide, 4 times as long as wide. Heads of spermatozoa 15 µm long. Vasa deferentia muscular, 100–140 µm long, in XII only; 15 µm wide near sperm funnel, gradually narrowing to 8 µm, internally ciliated. Penial apparatuses (Fig. 2 C) with uniform oval glandular structures, 65–100 µm long, 45–70 µm wide, next to epidermal invaginations; vasa deferentia opening into epidermal invaginations; curved stylets present, 60–70 µm long (penial bulb type 6). Egg sac extending to XVIII–XXIV. Spermathecae (Fig. 2 D) attached to oesophagus in mid V through narrow ental ducts; ampullae roughly spherical, 40–55 µm in diameter, ectal ducts 25–30 µm long, widening from a thickness of 10 µm at pore to 25 µm at connections to ampullae; 10–12 sperm rings per spermatheca, 6–8 µm in diameter; sperm also occurring freely in ampullae; no glands at spermathecal pores.
Etymology: From the Latin brevis, meaning short, and ductus, referring to the short vasa deferentia, not extending longer than within XII.
Remarks: Grania breviductus is recognizable by its short, muscular vasa deferentia combined with penial stylets. It is similar to G. fiscellata De Wit & Erséus, 2007, from New Caledonia, and G. m i r a Locke & Coates, 1998, from Ireland, considering the short, muscular vasa deferentia, the shape of the spermatheca with a short duct and a sac-like ampulla, and the spermathecal ental connection to the gut in mid V. These features could well be synapomorphies, testifying of a close evolutionary relationship. The rather uniform chaetal size throughout the body also suggests a close affinity between these three species. In contrast to the other two taxa, however, the penial bulb of G. breviductus possesses a penial stylet, and ventral chaetae occur from VI (from IV in G. fiscellata and G. m i r a).
The large, round spermathecal ampullae of G. breviductus also resemble those of G. hyperoadenia Coates, 1990, from south-western Australia (see also present new record from Lizard Island), but again, the chaetal distribution differs (G. hyperoadenia has a chaetal distribution like that of G. fiscellata and G. m i r a). Furthermore, G. breviductus possesses L-shaped chaetae with heels, which neither G. fiscellata, G. m i r a nor G. hyperoadenia have. Finally, G. hyperoadenia lacks the penial stylets which are prominent in G. breviductus.
Distribution and habitat: Heron Island, Great Barrier Reef; intertidal coarse sand. Only known from the beach at the Research Station.
description: Published as part of Wit, Pierre De, Rota, Emilia & Erséus, Christer, 2009, Grania (Annelida: Clitellata: Enchytraeidae) of the Great Barrier Reef, Australia, including four new species and a re-description of Grania trichaeta Jamieson, 1977, pp. 16-38 in Zootaxa 2165 on pages 19-21, DOI: 10.5281/zenodo.189048