Amblyosyllis

Paresque, Karla, Fukuda, Marcelo Veronesi, Martín, Guillermo San & Nogueira, João Miguel De Matos, 2015, Amblyosyllis, Eusyllis, Odontosyllis, Perkinsyllis and Streptodonta (Annelida: Syllidae) from Brazil, with descriptions of two new species and new records for the country, Zootaxa 4000 (3), pp. 301-334 : 321-325

Amblyosyllis sp.

Figures 12–14

Material examined. Project ‘BioPol-NE’. State of Paraíba, João Pessoa, Recife do Picãozinho (7°4.243'S 34°49.291'W), intertidal: 1 specimen ( MZUSP 2745), coll. 15 September 2012.

Additional material examined. Amblyosyllis enigmatica San Martín & Huchings, 2006 . Australia, New South Wales, Jervis Bay, northwestern corner of Bowen Is. (35°06.81'S 150°46.11'E), dense bryozoan community under rock ledge, 13 m: 1 specimen (AM W28943, holotype), coll. 8 December 1993, coll. P. Serov & G.D.F. Wilson. Amblyosyllis multidenticulata San Martín & Huchings, 2006 . Australia, New South Wales, Port Jackson (33°51'S 151°16'E): 1 specimen (AM W502, holotype), coll. February 1920, coll. W.A. Haswell, det. G. San Martín, mounted on microscope slide. Australia, New South Wales, Port Jackson (33°51'S 151°16'E): 1 specimen (AM W25245, paratype), mounted on slide, id. W.A. Haswell as A. spectabilis . Australia, New South Wales, Ulladulla, Halfway Reef, 200 m south of Sullivan Reef (35°21.42'S 150°29.31'E), red algae on rock ledges at base of wall, 13 m: 2 specimens (AM W28229, paratypes), coll. 3 May 1997, coll. A. Murray, det. G. San Martín. Amblyosyllis speciosa Izuka, 1912 . Japan, Hokkaido, off Oma (41°41.5'N 141°08.5'E), 126 m: 1 specimen ( NSMT 625), coll. 0 2 February 1956, coll. & det. M. Imajima. Japan, Tōhoku, Onagawa (38°26.2'N 141°27.5'E), intertidal zone: 5 specimens ( NSMT 627-632), coll. June 1964, coll. & det. M. Imajima. Japan, Kyushu, Sagami Bay (35°09.3'N 139°37.0'E), intertidal zone: 6 specimens ( NSMT 636-646), coll. May 1964, coll. & det. M. Imajima.

Description. Small-sized body, 3.2 mm long, 0.42 mm wide, with 13 chaetigers plus some achaetous segments. Conspicuous pigmentation on living animal, with dorsal dark brown spots along dorsal surface, arranged in 2–3 irregular rows ( Figs 12 ; 13A, D). Palps free, ventrally bent, not visible dorsally ( Fig. 13 B). Prostomium ovate with two coalescent pairs of red eyes in trapezoidal arrangement, anterior eyespots absent ( Figs 12 ; 13A); antennae of similar length, elongate, ca. four times as long as body width at anterior segments; lateral antennae inserted on anterior margin of prostomium, median antenna inserted between anterior pair of eyes; antennae basally smooth to pseudoarticulated, distally tapering, with roughly cubic articles from midlenght; pair of ciliated, elongate nuchal épaullètes, extending to posterior border of chaetiger 2 ( Figs 12 ; 13A). Peristomium reduced, not visible dorsally, slightly shorter than chaetiger 1 ventrally ( Fig. 13 B); dorsal peristomial cirri elongated, slightly longer than antennae, basally smooth to pseudoarticulated, with elongated articles from midlenght; ventral peristomial cirri shorter than body width, smooth to pseudoarticulated ( Fig. 13 A–B). Dorsal cirri on chaetiger 1 approximately same length as antennae, basally smooth to pseudoarticulated, with elongated articles from midlenght; dorsal cirri of chaetiger 2 smooth, slightly shorter; remaining anterior dorsal cirri ca. 1.5 times as long as body width at corresponding segment, smooth or pseudoarticulated, with elongated articles from midlenght of cirri ( Fig. 13 A); from midbody, dorsal cirri pseudoarticulated ( Fig. 13 C–D), ca. 1.5–2 times as long as body width at corresponding segment. Antennae, peristomial and dorsal cirri throughout with short cirrophores and distally tapering cirrostyle. Ventral cirri conical to pyriform, with small pigmented granules ( Fig. 14 A–B); anterior ventral cirri inserted on basal half of parapodia, extending beyond parapodial lobes ( Fig. 14 A); ventral cirri of posterior chaetigers inserted near midlength of parapodia and not extending beyond parapodial lobes ( Fig. 14 B). Parapodial lobes conical, with dorsal pre-chaetal lobe ( Figs 12 ; 13A; 14A–B). Anterior parapodia with ca. 22 falcigers each, mid- and posterior parapodia with ca. 25 falcigers each; shafts of falcigers slightly inflated and spinulated subdistally ( Fig. 14 C–D); blades of falcigers with short spinulation, distally bidentate, teeth directed forwards and of similar size, or subdistal tooth slightly shorter ( Fig. 14 C–D); blades with dorso-ventral gradation in length, 78–42 µm long on anterior chaetigers, 92–55 µm long on midbody, 95–50 µm long on posterior chaetigers. Dorsal and ventral simple chaetae absent. Anterior and midbody parapodia with four aciculae each, posterior parapodia with 3–4 aciculae each; aciculae straight, thick, distally acuminate, with tips protruding from parapodial lobes ( Fig. 14 E–F). Pharynx through three segments, with one sinuation, trepan not seen; proventricle through two segments, with ca. 15 muscle cell rows.

Remarks. Amblyosyllis sp. resembles A. speciosa Izuka, 1912 and A. formosa ( Claparède, 1863) in having elongated nuchal épaulèttes, extending to posterior margin of chaetiger 2, parapodia all similar throughout, with digitiform pre-chaetal lobe, 20–30 falcigers and 3–4 aciculae each, aciculae straight, thick and distally acuminate, tips protruding from parapodial lobes, and short proventricle, with up to 15 muscle cell rows ( San Martín 2003). Amblyosyllis speciosa also has ventral cirri with granules ( Aguado et al. 2008), but that species has midbody falcigers with shorter blades, ca. 20 µm long (92–55 µm long in Amblyosyllis sp.) and anterior appendages articulated, pseudoarticulated in Amblyosyllis sp. Amblyosyllis formosa has different colour pattern, San Martín (2003) noticed variation in the dorsal pigmentation ranging from beige to dark dorsum with some bright spots. Also, A. formosa has smooth to pseudoarticulated dorsal cirri and pharynx with several sinuations ( San Martín 2003), while Amblyosyllis sp. has some midbody dorsal cirri conspicuously articulated and pharynx with single sinuation.

Amblyosyllis enigmatica San Martín & Huchings, 2006 and A. multidenticulata San Martín & Huchings, 2006 from Australia have nuchal épaulèttes not extending beyond chaetiger 1 (chaetiger 2 in Amblyosyllis sp.), 6–8 and 5–6 aciculae per parapodium, respectively (3–4 in Amblyosyllis sp.) and a pharynx with several sinuations (single sinuation in Amblyosyllis sp.).

Since we did not see the trepan, an important character to distinguish the species in this genus, we decided not to give a formal name to our single specimen until we have more material.

Distribution. Atlantic Ocean: Brazil (Pernambuco). First record of the genus for northeast Brazil.

Figures

FIGURE 12. Amblyosyllis sp. specimen alive, dorsal view. Scale bar: 0.3 mm.

FIGURE 13. Amblyosyllis sp. (A), (B) anterior end, dorsal and ventral views, respectively; (C) dorsal cirrus, midbody; (D) posterior end, dorsal view. Scale bars: A – B, 0.4 mm; C, 0.1 mm; D, 0.3 mm.

FIGURE 14. Amblyosyllis sp. (A), (B) anterior and posterior parapodia, respectively; (C), (D) falcigers, anterior and posterior parapodia, respectively; (E), (F) aciculae, anterior and posterior parapodia, respectively. Scale bars: A – B, 100 Μm; C – D, 20 Μm; E, F, 10 Μm.