Branchiosyllis maculata

Branchiosyllis maculata (Imajima, 1966)

Fig. 2A

Typosyllis maculata Imajima 1966: 277, Fig. 59 a–m.

Branchiosyllis maculata Licher 1999: 274; Aguado et al. 2008: 10–13, Figs 3–4; San Martín et al. 2008: 131, Figs 9A–G, 10C–F, 11A–F, 13A, B.

Material examined. Luzón Island, Balayan Bay: 3 specimens (MNCN 16.01/14325), "Sepok Wall", between Balayan Bay and Batangas Bay, 13º41'02"N – 120º53'45"E, unidentified sponge and gogonians, 13 m deep, coral rubble, 6 m deep, 10 December 2010; 3 specimens (MNCN 16.01/14326), 13º44'26"N – 120º53'34"E, coral rubble, 2–3 m deep, 7 December 2010; 1 specimen (MNCN 16.01/14327), "Koala Point", 13º47'56"N – 120º52'10"E, coral rubble, 1–2 m deep, 5 December 2010; 3 specimens (MNCN 16.01/14328), 13º44'26"N – 120º53'34"E, hidrozoans, gorgonians (Siphonogorgia sp.), ascidians (Atriolum sp.) and coral rubble, 2–4 m, 4 December 2010; 5 specimens (MNCN 16.01/14329), “Sombrero Island”, 13º41'51"N – 120º49'45"E, unidentified ramified sponges, 2–3 m deep, 6 December 2010; Palawan Island, El Nido: 1 specimen (MNCN 16.01/14330), “Popollcan”, 11º11'50"N – 119º17'06"E, coral rubble, 3 m deep, 15 December 2010; 1 specimen (MNCN 16.01/14331), “South Intalula”, 11º08'01"N – 119º19'02"E, sandy bottom, 5 m deep, 15 December 2010.

Comparative material. Branchiosyllis maculata, 1 specimen (AM W41617) Cassini, stn 59/K10, Q3, 13°56' 01"S – 125° 37'09"E, mid-littoral reef platform, Flat reef pavement with an extensive cover of Sargassum sp. over a dusting of sediment, 0 m deep, Woodside Kimberley Survey 2010, 25 October 2010; 4 specimens (AM W30108), inshore reef off Neds Camp, Cape Range National Park, 21°59'S – 113°59'E, frilly Caulerpa sp., 1 m deep, 2 January 1984; 2 specimens (AM W30109) Bundegi Reef, Exmouth Gulf, 21°49'S – 114°11'E, rocky rubble with sediment, brown algae with epiphytic growth, intertidal, 4 January 1984; 3 specimens (AM W29519), N end of beach, Bundegi Reef, 21°49'S – 114°11'E, rocky rubble & brown alga with epiphytic growth, sticky sediment, 2 m deep, 4 January 1984. Branchiosyllis cirropunctata, 2 specimens (AM W30091), Goss Passage, Beacon Island, 28°25'30"S – 113°47'E, dead plates of Acropora sp. covered in coralline algae, 8 m deep, 19 May 1994; 1 specimen (AM W30092), NE entrance to Goss Passage, Beacon Island, 28°27'54"S – 113°46'42"E, dead plate-like Acropora sp., covered in coralline algae, 8 m deep, 25 May 1994; 1 specimen (AM W21993), Outer Koombana Bay, 33°18'46"S – 115°38'58"E, 9.4 m deep, 27 March 1993; 1 specimen (AM W30094), Pondalowie and Marion Bays, Yorke Peninsula, 35°14'S – 136°50'E, Caulerpa sp. and green algae 3 m deep, 22 February 1985. Branchiosyllis exilis, 4 specimens (AM W30095), Kimberley region, Bernouli Island, 15°S – 124°47'E, sandy substrate with coral rubble, intertidal, 12 July 1988; 1 (AM W30099), SW corner of Lucas Island, 15°13'S – 124°31'E, dead coral substrate, 2–30 m, 24 July 1988; 10 specimens (AM W30101), inshore reef off Neds Camp, Cape Range National Park, 21°59'S – 113°59'E, Caulerpa sp., 1 m deep, coll. J.K. Lowry, 2 January 1984.

Description. Body cylindrical, ventrally flattened, pigmentated with one dorsal spot or narrow line of black pigment on middle of each segment from midbody parapodia and black spots on numerous articles of dorsal cirri. Prostomium rounded with four eyes in open trapezoidal arrangement. Median antenna longer than combined length of prostomium and palps, inserted between anterior eyes; lateral antennae inserted on anterior margin of prostomium, shorter than median antenna. Dorsal tentacular cirri similar in length to median antenna, ventral ones shorter than dorsal tentacular cirri. Dorsal cirri of first chaetiger longer than other ones; midbody and posterior dorsal cirri alternating long and short. Parapodial lobes distally bilobed. Anterior and midbody parapodia with dorsal compound bidentate chaetae dorsoventrally decreasing in length, and ventral unidentate chaetae, all of them with marginal spines; midbody parapodia present also two to three unidentate chaetae without spines, short shafts and short blades, some of them rotated 180º. In posterior parapodia these chaetae are more curved, becoming ungulae. Anterior parapodia each with three slender aciculae, two straight and pointed and one slightly oblique at tip; midbody and posterior segments with two to three aciculae protruding from parapodia, one or two straight and pointed, other slightly oblique at tip. Pharynx through about seven segments; pharyngeal tooth located anteriorly, surrounded by crown of ten soft papillae. Proventricle longer than pharynx, through 12 segments. Pygidium small, with 2 anal cirri similar in length to dorsal cirri. Some specimens with attached pink coloured acephalous stolon, small, short, with 6–8 chaetigers (Fig. 2D).

Remarks. The studied specimens agree well with the original description of B. maculata, with the Australian material and with those described from Indonesia (Aguado et al. 2008). Branchiosyllis cirropunctata is a similar species, but it possesses ungulae in its far posterior segments with subdistal spurs on the head of the shaft. Branchiosyllis exilis differs in having anterior bidentate falcigers with more spines on edge of blades and larger than those of B. maculata. The colour pattern is also a very distinctive character in well preserved specimens.

Habitat. Intertidal to shallow depths, among coral rubble, algae and sponges.

Distribution. West Pacific Ocean (Southern Japan, Philippines, Australia), Indonesia.