Haplosyllis imajimai Lattig & Martin & Martín 2010, sp. nov.

Haplosyllis imajimai sp. nov.

Figs 8A–I, 9A–F

Examined material. AUSTRALIA. SOUTH AUSTRALIA: HOLOTYPE, AM W14020 and 2 PARATYPES AM W36593: American Bay, Kangaroo Island, 35º47'08''S 137º46'31''E, coll. by H. Duyverman, 1976.

Additional material examined: VICTORIA: 2 specimens AM W29550, Corio Bay, Port Phillip Bay, 38°06'S 144°25'55"E, 5m, silty clay, coll. Marine Science Lab, Corio Bay Benthic survey, 1 July 1987. NORTHERN TERRITORY: 1 specimen AM W36594, Darwin Harbour, East Point, 12°24'36''S 130°39'57''E, 7–10 m, dead coral rubble and algal washings, coll. P.A. Hutchings, 17 July 1993. WESTERN AUSTRALIA: 1 specimen AM W36595, Goss passage, Beacon Island, 28º25'30''S 113º47'E, 20 m, dead plates of Acropora, covered in coralline algae, coll P.A Hutchings, 20 May 1994. 2 specimens AM W36597, Lafontaine Island, Kimberleys, 14º10'S 125º47'E, 15m, coll. P.A. Hutchings, 19 July 1988. 4 specimens AM W36596 (plus 1 mounted for SEM), Beacon Island, off south end of Long Island, 28°28'48''S 113°46'18''E, 5 m, dead coral substrate, covered in coralline algae, coll. P.A. Hutchings, 25 May 1994. 1 incomplete specimen AM W28398, west of Penguin Island, Warnbro Sound, 32º18'S 115º41'E, 5m, reef substrate, algae and sponge, coll. P.A. Hutchings, 21 March 1993. 1 specimen AM W28378, Wallabi group of Islands, 28º24'07''S 113º47'23''E, 40 m, medium sand with scallops, rubble, coll. P.A. Hutchings, 28 May 1994.

Description. (Measurements in parenthesis from additional material examined)

Body robust, broadest in proventricular segments, gradually tapering towards posterior end (Fig. 9A). Holotype and two paratypes measuring 2.6–2.8 (1.4–2.7) cm long, with 107–117 (46–126) segments. Body pale yellow when preserved, with round, small dorsal granules; dorsal pigment pattern absent. Prostomium subpentagonal, wider than longer, with two pairs of small red eyes in trapezoidal arrangement (Fig. 8A). Median antennae broken in most observed specimens, inserted on middle of prostomium between eyes (about 30 articles); lateral antennae inserted on anterior prostomial margin, with 20–25 articles. Palps longer than prostomium, broadly triangular, fused at their bases but separated all along their length. Sensory organs of palps and nuchal organs not seen. Pharynx orange, broad, difficult to see, extending through 8 (7) segments, with a long triangular anterior tooth, surrounded by crown of about 10 soft papillae and inner ring of cilia; ventral-upper side of papillae with cilia (Fig. 9B). Proventricle very long, cylindrical, dark-brown, as wide as pharynx, extending through 16 (9–11) segments; number of muscle cell rows impossible to assess. Peristomium well defined, shorter than subsequent segments, difficult to see when pharynx everted (Fig. 8A). Dorsal tentacular cirri longer than ventral ones, with 32 (25–35) articles. Antennae, tentacular cirri and dorsal cirri similar. Dorsal cirri slender, first cirri longer than remaining ones, with 33 (30–31) articles; thereafter, all similar in length (19–30 articles), longest ones slightly exceeding body width. Ventral cirri digitiform, anterior ones broad, as long as parapodial lobes (Figs 8B, 9C); median and posterior ventral cirri small, slender, much shorter than parapodial lobes (Fig. 8C). Chaetae all bidentate, 3–5 per parapodia, with few short denticles on US of MF; anterior chaetae with short main fang (Figs 8D, 9D); median and posterior chaetae with MJP straight, long; LMF similar in length or longer than SW, apical teeth short, similar in size, with narrow angle (Figs 8G, 9E–F). Most aciculae straight, some with curved tip bent at 90º; 4–5 in anterior and median parapodia (Fig. 8E–F); 2–3 in posterior parapodia (Fig. 8H–I). Pygidium not seen.

Reproduction. Not known.

Remarks. Haplosyllis imajimai sp. nov., is characterized by its robust, broad and long body, 3–5 aciculae per parapodia, and the long MJP. The new species differs from H. djiboutiensis in its robust body, the median cirri (which are all similar in length) and chaetal form (which are all similar in each parapodia). H. imajimai sp. nov., resembles H. cf. spongicola in body robustness, but the latter has a clear alternation in cirri length, the MJP is curved and short, and it usually have one acicula in posterior parapodia.

The Mediterranean Haplosyllis spongicola resembles H. imajimai sp. nov., in body size and acicular shape. However, in the former, the anterior and median chaetae have different morphologies (all similar in H. imajimai sp. nov.). In turn, H. uncinigera differs from H. imajimai sp. nov., in the shape of median and posterior chaetae (see below).

Distribution. AUSTRALIA (Victoria, Western Australia and Northern Territory).

Etymology. The species name refers to Dr. Minoru Imajima from the National Science Museum, Tokyo, who studied the syllids from Japan and significantly contributed to the knowledge on the whole family.