Grania breviductus , Wit, Pierre De, Rota, Emilia & Erséus, Christer, 2009

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, Zootaxa 2165, pp. 16-38: 19-21

publication ID

http://doi.org/ 10.5281/zenodo.189048

persistent identifier

http://treatment.plazi.org/id/FB45AF01-C96D-8761-80E2-FD14FC81A1C7

treatment provided by

Plazi

scientific name

Grania breviductus
status

sp. n.

Grania breviductus  sp. n.

( Figs. 2View FIGURE 2, 10View FIGURE 10 A)

Holotype: AMS type coll. W. 35536, whole-mounted specimen from Heron Island, stn. H 1.

Paratypes: AMS type coll. W. 35537 -W.35542, 6 whole-mounted specimens from Heron Island: 3 from stn. H1, 2 from stn. H 8, and 1 from stn. H 2. SMNH type coll. 7761 -7766, 6 whole-mounted specimens from Heron Island, stn H 8.

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. 2View FIGURE 2 A, 10 A). 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. 2View FIGURE 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 8 x 15 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. 2View FIGURE 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. 2View FIGURE 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.

SMNH

Saskatchewan Museum of Natural History