Syllides japonicus Imajima, 1966

San Martin, G & Hutchings, PA, 2006, Eusyllinae (Polychaeta: Syllidae) from Australia with the Description of a New Genus and Fifteen New Species, Records of the Australian Museum 58, pp. 257-370 : 360-361

Syllides japonicus Imajima, 1966

Figs 86C–F, 87A–E

Syllides japonicus Imajima, 1966: 112 , text-fig. 36.—San Martín, 2003: 142, fig. 69.

Material examined. AUSTRALIA: NEW SOUTH WALES: 1 km SE of Dangar Is., Hawkesbury R., 33°33'S 151°14'E, shelly mud, 9 m, coll. A.R. Jones & party, 18 Dec 1979, 1 ( AM W28467) ; Pittwater , 33°35.80'S 151°18.31'E, muddy sand, 14.4 m, coll. Australian Museum Party, 31 July 1995, 2 ( AM W23927) ; 1 km SE of Dangar Is., Hawkesbury R., 33°33'S 151°14'E, shelly mud, 9 m, coll. A.R. Jones & party, 1 Aug 1979, 1 ( AM W28975) ; 1.5 km SE of Dangar Is., Hawkesbury R., 33°33'S 151°14'E, sandy mud, 7 m, coll. A.R. Jones & party 18 Dec 1979, 1 ( AM W28976) . TASMANIA: Fancy Point, Bruny Is. 43°16'S 147°19'E, algae, 4 m, coll. G. Edgar, 10 Nov 1980, 1 ( AM W18204) . WESTERN AUSTRALIA: Inshore limestone reef, Ned’s Camp, Cape Range National Park , 21°59'S 113°55'E, Caulerpa sp. algae, 1 m, coll. J.K. Lowry, 2 Jan 1984, 1 ( AM W26739) ; Inshore limestone reef, Ned’s Camp, Cape Range National Park , 21°59'S 113°55'E, small purple sponge with Caulerpa sp. algae & sticky sediment, 1.5 m, coll. R.T. Springthorpe, 2 Jan 1984, 2 ( AM W26781) .

Description. Body less than 5 mm in length, densely covered with golden inclusions on dorsum of each segment and prostomium ( Fig. 87A). Prostomium oval, about twice as wide as long; 4 small eyes in open trapezoidal arrangement; antennae missing on most specimens, short, smooth. Palps broad, fused at bases, shorter than prostomium, each ending with distal, small papilla ( Figs 86C,D, 87A). Tentacular and dorsal cirri mostly missing. Parapodia elongated, ventral cirri digitiform. Compound chaetae with elongated, distinctly bidentate blades, arranged in 5 pairs of chaetae within fascicle, each pair of similar shape and length; blades of dorsalmost pair with long blades, about 55 µm long, with basal long spur ( Figs 86F, 87D) and short spines on margin; blades of subsequent pair similar ( Fig. 87E) but shorter, about 44 µm long; remaining compound chaetae similar in shape, lacking basal spur ( Fig. 87E), with dorsoventral gradation in length of blades, 35 µm in length dorsally and 22 µm in length ventrally. Dorsal simple chaetae from chaetiger 1, thin, pointed ( Figs 86E, 87B), with short spines on margin ( Fig. 87B). Ventral simple chaetae absent. Aciculae slender, distally knobbed ( Fig. 87C) pharynx everted on most specimens, through about 4 segments when relaxed. Proventricle long, through 7 segments ( Fig. 87A), with about 47 muscle cell rows.

Remarks. The original description of the species from Japan and descriptions of Mediterranean specimens do not describe the terminal papillae on the palps; these structures are small and could easily be overlooked. This species is characterized by having basal spurs on the bases of blades of the dorsalmost and second pair of compound chaetae; palps each with a small papilla on the Australian material, and dorsal simple chaetae, slender. Syllides caribica Licher, 1996 , from Aruba Island in the Caribbean is similar, but differs in the following characters: the spurs on the compound chaetae are shorter, and have a smooth area between the spur and the edge of blade, the proventricle is shorter (through 2 segments), and the dorsal simple chaetae are slightly thicker (see Licher, 1996). Syllides floridanus Perkins, 1981 also has papillae on the palps, a long proventricle and slender, distally pointed dorsal simple chaetae; but the blades of the dorsalmost pair of compound chaetae lack basal spurs; they are present only on the second pair ( Perkins, 1981).

All the material examined from Australia is damaged and while it closely resembles material examined from the Mediterranean, it may represent an undescribed species, but complete specimens are needed in order to confirm this.

Habitat. Occurring in sand, sandy mud, rhizomes of Posidonia , on algae and sponges; in shallow depths.

Distribution. Japan, Western Mediterranean, USA (Massachusetts), Australia (New South Wales, Tasmania, Western Australia).