Hauchiella tentaculata n. sp.

(Fig. 2)

Hauchiella renilla Hutchings & Glasby 1986: 323 –325, figs 2a, b; 12B (in part).

Type material. Holotype: NTM W. 023154, Mermaid Cove, 14˚23'15.101”S, 145˚16'19.776”E, 2–3 m, coll. C. Glasby & C. Watson, 2010, fore reef (mid-shelf), complete specimen, 7 mm long, ~ 1 mm maximum width, at abdomen. Paratypes: AM W.199608 and AM W.199609, both from the Lizard Island lagoon, 14˚40'S, 145˚27'E, originally paratypes of H. renilla Hutchings & Glasby, 1986 .

Other material examined. AM W.199603, AM W.199592, AM W.199602, AM W.199600, all from Lizard Island lagoon, 14˚40'S, 145˚27'E.

Comparative material examined. Holotype of Hauchiella tribullata, BMNH 1921.5.1.4120. Holotype of Hauchiella renilla, AM W.199607; paratypes of Hauchiella renilla, AM W.199610, AM W.199611, AM W.199614.

Description. Prostomium at base of upper lip, both basal and distal parts developed, basal part as thickened horseshoe-shaped crest, distal part as flaring spongy lobes; prostomium covering segment 1 laterally and continuing ventrally, terminating posteriorly to lower lip, below mouth (Fig. 2 A–C, E–I). Numerous buccal tentacles, of three types; short ones remarkably thin, uniformly cylindrical; intermediate tentacles distally broader, spatulated; long tentacles with thin, uniformly cylindrical peduncle and progressively widening distally towards cylindrical swelling, followed by relatively long, tapered tip, with deep groove (Fig. 2 A–G). Peristomium restricted to lips, upper lip relatively short, longer than wide; lower lip short, rounded, button-like (Fig. 2 B–C, E, G–H). Body with short, almost uniformly cylindrical thoracic region of 6 progressively longer segments, followed by increasingly more swollen abdomen (Fig. 2 A–J). Thoracic segments annulated, with several rows of papillae, especially ventrally; papillae extending onto anterior abdominal segments, progressively less numerous, followed by distinctly swollen posterior region, with inconspicuous segmentation and fragile body wall (Fig. 2 A–C, G–J). Segment 1 short, conspicuous all around; segment 2 longer dorsally, as short annulation ventrally, with relatively large mid-ventral shield at beginning of mid-ventral groove (Fig. 2 A–C, E–I). Ventrum highly glandular, paired ventro-lateral pads extending to segment 6, covered with relatively large papillae arranged in several transverse rows (Fig. 2 B–C, E, G–H). Holotype with abdomen full of gametes (oocytes), present from segment 7, but distinctly more abundant on posterior body; nephridial and genital papillae inconspicuous or not seen, and nephridia also not visible through body wall (Fig. 2 A–C, E–J). Pygidium surrounded by crown of papillae, all about same size (Fig. 2 A, J).

Remarks. As said above, the absence of noto- and neuropodia, and the consequent inapplicability of all chaetal-related characters, renders it difficult to distinguish between species of Hauchiella, but to date, all have been described from very different habitats and localities.

Hauchiella tribullata McIntosh, 1869 is a large species, the holotype incomplete and in two pieces, ~ 20 mm long, 2 mm wide at widest point of body (anteriorly), with robust anterior segments until around segments 15–20, then tapering to uniformly cylindrical, slightly narrower posterior body. The holotype has very few buccal tentacles remaining, all apparently uniformly cylindrical, a large, convoluted upper lip of width greater than length, and large, rounded nephridial papillae on segments 6–8. This species was described from St Magnus Bay, Shetlands, Scotland, dredged from 165 m on muddy substrates.

The second species in this genus, H. renilla Hutchings & Glasby, 1986 is smaller, the holotype 12 mm long, ~ 2.5 mm wide, with narrower segments until segment 10, then swollen, with fragile body wall and inconspicuous segmentation. The buccal tentacles are of at least two types, the long ones distally spatulated, with relatively long tips, and the upper lip is distinctly longer than wide. Nephridial and genital papillae are absent, but 10 pairs of elongate nephridial sacs are visible through the transparent body wall, with minute pores visible in some mature material having body wall distended with oocytes. This species was described from the Australian Capital Territory, Wreck Bay (type locality), in depths of 5–10 m, and with additional material collected from One Tree Island on the southern GBR, as well as Lizard Island lagoon, but this latter material was re-examined and found to have been misidentifed. These specimens are now transferred to H. tentaculata n. sp. as they possess the long specialised tentacles and a similar upper lip and thus clearly differ from the type material of H. renilla .

Hauchiella tentaculata n. sp. is also a smaller and more fragile species than H. tribullata, the holotype complete, 7 mm long, ~ 1 mm wide at widest point (mid-abdomen), with narrow, clearly marked and uniformly cylindrical anterior segments, until segment 6, then body distinctly swollen, with fragile body wall, inconspicuous segmentation and coelom full of oocytes, visible through the transparent body wall. The long buccal tentacles of H. tentaculata n. sp. are highly specialised at tips, resembling those of some species of Lysilla and Amaeana, and a few of Polycirrus, with narrow, uniformly cylindrical peduncle, distally widening towards deeply grooved cylindrical swelling, with pointed tip. The upper lip is longer than wide, but smaller than in members of H. renilla, while the anterior segments are highly papillated ventrally, more than in specimens of both the other species of this genus. Nephridia have not been observed in H. tentaculata n. sp. and there are no visible nephridial or genital papillae, even though the body wall is transparent and oocytes and the gut are visible.

Etymology. The name “ tentaculata ” is attributed for this species in reference to the modified long tentacles, which are not known to occur in any other species of this genus.

Habitat. Shallow waters 2–3 m on ‘fore reef’ (mid-shelf) in amongst coral rubble.

Type locality. Mermaid Cove, 14˚23'15.101”S, 145˚16'19.776”E, Lizard Island, Great Barrier Reef, Australia.

Distribution. Known only from the Lizard region.