Syllis aciculigrossa (San Martín, 1990)

Figure 11

Pionosyllis aciculigrossa San Martín, 1990: 604 –606, figs 10–11. Pionosyllis sp. B. Uebelacker 1984: 30 –69, figs 30-61–30-62.

Typosyllis aciculigrossa . Licher 1999: 36 –37.

Syllis aciculigrossa . Fukuda 2010: 246 –250, fig. 70; Barroso 2011: 90 –92, fig. 8.

Material examined. Project ' Oceanprof '. 22°27’31.1”S, 40°09’23.5”W, 2–5 cm, 749 m deep: 1 spec. (MNRJP 1185), 18 Jun 2003. Project ‘ AMBES ’. 19°34’20”S, 38°41’18”W, 450 m deep: 8 specs, 9 Dec 2011; 19°36’26”S, 39°10’17”W, 392 m deep: 12 specs (MZUSP 2899), 14 Dec 2011; 19°49’7”S, 39°36’8”W, 158 m deep: 3 specs, 14 Jan 2012; 19°49’37”S, 39°35’41”W, 410 m deep: 1 spec., 14 Jan 2012; 20°14’17”S, 39°48’34”W, 395 m deep: 16 specs (MZUSP 2901), 19 Jun 2013; 20°35’16”S, 39°53’47”W, 410 m deep: 22 specs, 8 Jan 2012; 21°4’9”S, 40°13’7”W, 410 m deep: 2 specs, 30 Dec 2011.

Additional material examined. Pionosyllis aciculigrossa — United States, Florida, Gulf of México, off Panamá City (29°30'02"N, 86°24'59"W, 189 m deep): 1 spec. (USNM 65684, paratype), coll. BLM/ MMS, Sep 1975, det. G. San Martín, 1989 ; United States, Texas, Gulf of Mexico (26°58'12"N, 96°33'W, 106 m deep): 1 spec. (USNM 89890, paratype), coll. BLM/ MMS, 1976, det. G. San Martín, 1989.

Description. Body slender, subcylindrical. Largest specimen analyzed incomplete, 23 mm long, 1 mm wide, with 134 chaetigers. Palps longer than prostomium, fused along basal third. Prostomium ovate, with 2 pairs of eyes in trapezoidal arrangement; median antenna inserted slightly backwards to middle of prostomium, with ~26 articles; lateral antennae inserted anteriorly to anterior pair of eyes, with ~22 articles each (Fig. 11 A). Peristomium slightly shorter than anterior body chaetigers, dorsal peristomial cirri with ~20 articles each, ventral peristomial cirri shorter, with ~15 articles each. Dorsal cirri of chaetiger 1 about same length as median antenna, longer than remaining dorsal cirri, with ~25 articles each; dorsal cirri throughout with length equivalent to about half body width of corresponding chaetiger, articles progressively more elongate distalwards on each cirrus (Fig. 11 A), and also posteriorwards along body; anterior dorsal cirri with 13–17 articles, 8–13 articles per cirrus from proventricle level; ventral cirri shorter than parapodial lobes, digitiform. Parapodial lobes conical, progressively more slender and elongate towards posterior body. Anterior parapodia with 25–30 compound chaetae each, midbody with 7–15, posterior parapodia with ~8 compound chaetae each; 1–3 dorsalmost compound chaetae throughout spiniger-like (Fig. 11 B), with unidentate, slightly spinulated blades, ~145 µm long on anterior body, 160–100 µm on midbody, 110–90 µm long on posterior body; falcigers on anterior body more slender than remaining, with apparently unidentate, spinulate blades (Fig. 11 C), blades 60–20 µm long; from midbody onwards, falcigers with spinulated and bidentate blades, distal tooth slightly larger (Fig. 11 D), blades 70–30 µm long on midbody, 50–32 µm long on posterior body. Dorsal simple chaetae only present on posterior body, thinner than shafts of falcigers, slightly sigmoid, bidentate, with short subdistal spines (Fig. 11 E); ventral simple chaetae only present on posteriormost parapodia, slightly thinner than shafts of falcigers, sigmoid, smooth and bidentate, distal tooth slightly larger (Fig. 11 F). Anterior parapodia with up to 7 aciculae each, one of which much thinner, remaining aciculae with rounded to blunt tips slightly protruding from parapodial lobes (Fig. 11 G); from proventricle region, 2 distally tapering aciculae per parapodium (Fig. 11 H), single acicula per parapodium from mid- to posterior body (Fig. 11 I), with acute tips, progressively more distinctly protruding from parapodial lobes towards posterior body (Fig. 11 G–I). Pharynx through ~8 chaetigers, with conical tooth close to anterior border, opening surrounded by crown of soft papillae; proventricle through 7–8 chaetigers, with ~36 rows of muscle cells (Fig. 11 A).

Remarks. The specimens herein studied agree with the paratypes examined, including in the presence of the apparently unidentate spiniger-like chaetae, which were not mentioned in the original description (San Martín 1990).

Geographic distribution and bathymetric range. Atlantic Ocean—Gulf of México (type locality, 106–189 m deep) (San Martín 1990) ; Brazil, states of São Paulo (280 m deep), Rio de Janeiro (102–750 m deep), and Paraná (480 m deep) (Fukuda 2010).