Pionosyllis yolandae, San Martin & Hutchings, 2006

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 : 348-351

Pionosyllis yolandae n.sp.

Figs 42C–F, 49A–C, 78A–J

Material examined. HOLOTYPE ( AM W28222) AUSTRALIA: NEW SOUTH WALES: Burrill Rocks , 35°23.39'S 150°28.24'E, on gorgonacean, 24 m, coll. R.T. Springthorpe, 7 May 1997 . PARATYPES 1 ( AM W28401) S ledge, Cook Is., 28°11.65'S 153°34.63'E, colonial ascidian, 14 m, coll. G.D.F. Wilson, 9 Jun 1993 ; 1 ( AM W28964) N side of Bannister Head , N of Ulladulla, 35°19.15'S 150°29.12'E, grey sponge from top of boulder, 18 m, K. Attwood, 6 May 1997 .

Other material examined. TASMAN SEA Taupo Seamount , 33°16.85'S 156°09.15'E, limestone & sand bottom, 244 m, coll. J.K. Lowry & party, on RV Franklin, 2 May 1989, 3 on SEM stub ( AM W28876) ; Taupo Seamount , 33°16.85'S 156°09.15'E, limestone & sand bottom, 244 m, coll. J.K. Lowry & party, on RV Franklin, 2 May 1989, few ( AM W28924) . WESTERN AUSTRALIA: Reef W of groyne, 2 km S of Cape Peron , 32°16'S 115°41'E, orange sponge in deep channel in limestone reef, 4.5 m, coll. R.T. Springthorpe, 26 Dec 1984, 1 ( AM W28965) .

Description. Body fragile, slender; only anterior fragments examined; longest anterior fragment 2.4 mm long, 0.3 mm wide, with 21 chaetigers; usually colourless, but some specimens with few dark transverse bands on dorsum of anterior segments, varying in intensity. Posterior to proventricle, segments fused, forming suprasegmental structures of 2–3 segments ( Fig. 78A). Prostomium oval, with 4 eyes in open trapezoidal arrangement; antennae irregularly articulated, originating on anterior margin of prostomium, median antenna inserted slightly posteriorly behind lateral antennae ( Figs 42D,E, 78A). Median antenna with about 15 articles, about twice combined length of prostomium and palps; lateral antennae about half length of median antenna, with about 6–8 articles. Palps blunt, similar in length to prostomium, free from each other, ventrally folded in several specimens ( Figs 42E, 78B). Peristomium shorter than subsequent segments, forming small, indistinct occipital flap ( Fig. 42C–E); dorsal tentacular cirri irregularly articulated, similar in length to median antenna; ventral tentacular cirri about half length of dorsal ones, almost smooth ( Fig. 78A,B). Nuchal organs as 2 dorsal densely ciliated grooves between prostomium and peristomium ( Figs 42D,E, 78A). Dorsal cirri of chaetiger 1 elongated, articulated, with about 13 irregular compound chaetae, anterior parapodium; (D) falcigers, anterior parapodium;

(E) spiniger-like compound chaeta, midbody; (F) falcigers, midbody; (G–J)

gradation on number and shape of aciculae from anterior parapodia to midbody.

AM W28876. Scales: A 0.18 mm, B 97.5 µm, C–J 20 µm.

articulations; dorsal cirri of remaining anterior parapodia slightly elongated, rugose, shorter than body width, becoming progressively shorter and smooth along body; midbody dorsal cirri alternating in length, longer ones about half of length of body width, shorter ones about two thirds length of longer ones ( Fig. 78A). Parapodial lobes conical; ventral cirri digitiform, slightly shorter than parapodial lobes; ventral cirri of chaetiger 1 leaf-like, enlarged, located mid ventrally ( Fig. 78B). Anterior parapodia with about 2– 3 compound chaetae with slender, spiniger-like blades bidentate, with short spines on margin ( Figs 78C, 49A), blades about 36 µm in length; 8–10 compound falcigerous chaetae with distinctly shorter blades, similar in shape but slightly larger ( Figs 78D, 49B), with dorsoventral gradation within fascicle, 22 µm in length dorsally, 15 µm in length ventrally. Progressively along body, number of compound chaetae with elongated blades decreases to 1–2 in midbody, 32 µm in length, remaining compound chaetae, about 6, with shorter and wider blades, about 10 µm in length, with prominent proximal tooth, similar in size to distal tooth or longer ( Fig. 78E,F). Dorsal and ventral simple chaetae not seen. Anterior parapodia with 2 tricuspid aciculae ( Fig. 78G), proventricular segments with single acicula, becoming progressively larger ( Fig. 78H,I), extending beyond parapodial lobes, with large tooth and 2 smaller ones ( Fig. 78J), similar in shape to subacicular hooks in eunicids ( Fig. 49C). Pharynx proportionally long and slender ( Fig. 78A), through 8–9 segments, anterior rim with crown of 10 soft papillae and layer of cilia ( Fig. 42F); pharyngeal tooth small, located slightly behind anterior rim. Proventricle about half of pharynx length, with about 20 muscle cell rows. Details of posterior segments unknown. Remarks. Pionosyllis yolandae n.sp. is similar to Pionosyllis aciculata San Martín, 1990 , from Cuba; but, this latter species has much shorter compound chaetae, with typical dorsoventral gradation in length of blades within a fascicle, and lacks elongated, spiniger-like compound chaetae ( San Martín, 1990). Pionosyllis lamelligera (Saint- Joseph, 1887) has spiniger-like chaetae, but it lacks the characteristic enlarged, tridentate aciculae, and the posterior falcigers have the proximal tooth longer than distal tooth present, whereas in Pionosyllis yolandae the teeth are of similar size (San Martín, 2003, for a description of Pionosyllis lamelligera ).

Habitat. Occurring on gorgonaceans, ascidians, sponges, and in sand, from 14 to 244 m depths.

Distribution. Australia (New South Wales, Western Australia).

Etymology. The species is named after Miss Yolanda Lucas, who helped us in many ways, especially collaborating with us on the illustrations of this paper.