Parexogone wolfi ( San Martín, 1991 ), San Martin, 1991

Barroso, Rômulo, Paiva, Paulo Cesar De, Nogueira, João Miguel De Matos & Fukuda, Marcelo Veronesi, 2017, Deep sea Syllidae (Annelida, Phyllodocida) from Southwestern Atlantic, Zootaxa 4221 (4), pp. 401-430 : 406-407

Parexogone wolfi ( San Martín, 1991)

Figure 3

Exogone (Parexogone) wolfi San Martín, 1991: 726 –727, fig. 6; 2003: 243–244, figs. 129–130; 2005: 111–113, fig. 64. Exogone sp. A. Uebelacker 1984: 30 –37, fig. 30.

Parexogone wolfi . Böggeman & Purschke 2005: 223 –225, fig. 2.

Material examined. Project ' Oceanprof '. 22°04’32.8”S, 39°54’11.4”W, 0–2 cm, 722 m deep: 1 spec. (MNRJP 1153), 30 Jun 2003; 22°04’33.9”S, 39°52’05.1”W, 0–2 cm, 1030 m deep: 1 spec. (MNRJP 1154), 30 Jun 2003; 22°04’43.3”S, 39°49’09.3”W, 0–2 cm, 1299 m deep: 1 spec. (MNRJP 1155), 25 Mar 2006; 22°35’03.7”S, 40°08’52.5”W, 0–2 cm, 1043 m deep: 2 specs (MNRJP 1156), 15 Jun 2003; 22°34’05.0”S, 40°00’12.6”W, 0–2 cm, 1337 m deep: 1 spec. (MNRJP 1157), 15 Jun 2003; 22°26’28.8”S, 39°58’53.3”W, 0–2 cm, 1046 m deep: 2 specs (MNRJP 1158), 20 Jun 2003; 22°30’21.7”S, 39°56’53.7”W, 0–2 cm, 1353 m deep: 1 spec. (MNRJP 1159), 21 Jun 2003. Project ‘ HABITATS ’. 21°42’37”S, 40°8’59”W, 147 m deep: 1 spec., 9 Mar 2009; 22°31’7”S, 40°31’32”W, 139 m deep: 8 specs, 23 Feb 2009; 23°11’29”S, 41°0’49”W, 150 m deep: 5 specs, 21 Feb 2009; 23°13’2”S, 40°57’36”W, 724 m deep: 3 specs, 24 Jun 2008; 23°13’48”S, 40°55’56”W, 986 m deep: 39 specs, 8 May 2009; 23°15’11”S, 40°53’53”W, 1302 m deep: 18 specs, 9 May 2008; 23°36’14”S, 41°21’29”W, 142 m deep: 1 spec., 1 Mar 2009. Project ‘ AMBES ’. 19°54’4”S, 39°22’27”W, 1335 m deep: 6 specs, 27 Jun 2013; 21°4’14”S, 40°14’14”W, 141 m deep: 1 spec., 11 Jul 2013.

Additional material examined. Parexogone wolfi — United States, Florida, off Port Everglades (26°00'54"N, 80°03'24"W), 188 m deep: 1 spec. ( USNM 101326 , holotype), det. G. San Martín, 1991 ; France, Bay of Biscay, Capbreton Canion (43°43'25"N, 02°18'17"W) 983–1032 m deep: 3 specs ( MNCN 16.01 /2948), coll. Campaña Capbreton 88, 8 Jul 1988, det. G. San Martín, Ceberio & Aguirrezabalaga .

Description. Body thin, elongate; longest specimen examined 6.0 mm long, 0.2 mm wide, with 67 chaetigers. Palps completely fused, triangular. Prostomium ovate, shorter than palps, with two pairs of eyes in trapezoidal arrangement, anterior and posterior eyes sometimes close to each other, nearly coalescent; antennae inserted slightly separated from each other; lateral antennae inserted slightly anteriorly to median antenna, approximately in front of anterior eyes, ovate to digitiform; median antenna inserted on middle of prostomium or slightly anteriorly, up to 5 times longer than lateral ones, reaching beyond tip of palps or chaetiger 4, if directed posteriorly ( Fig. 3 A, J). Peristomium shorter than subsequent segments; peristomial cirri ovate to papilliform, shorter than lateral antennae ( Fig. 3 A, J). Dorsal cirri on all chaetigers, papilliform, larger than peristomial cirri but shorter than lateral antennae ( Fig. 3 A, J); ventral cirri similar to peristomial cirri. Compound chaetae as spiniger-like and falcigers. Anterior parapodia with up to 3 spiniger-like chaetae each, from midbody onwards 1–2 spiniger-like chaetae per parapodium; shafts of spiniger-like chaetae from anterior and mid-body chaetigers with long and thin distal spines; blades bidentate and spinulate, spines of almost uniform length, except for the distalmost spines, much longer than remaining and directed distally, reaching beyond level of distal tooth ("aristae"); blades 55–35 µm long on anterior parapodia, 80–58 µm long on midbody and 40–10 µm long on posterior parapodia ( Fig. 3 B–D, K). Anterior parapodia with 8–10 falcigers each, midbody with 3–4, posterior parapodia with 2–3 falcigers each; shafts of facigers distally spinulated, spines longer on anterior body; falciger blades bidentate and spinulate, teeth close to each other, distal tooth slightly larger, blades with distally directed aristae reaching beyond level of distal tooth, sometimes absent on posterior body; blades of falcigers 22–11 µm long on anterior parapodia, 28–11 µm on midbody, and 12–8 µm long on posterior parapodia ( Fig. 3 B–D, L). Dorsal simple chaetae present from proventricle level, sigmoid, distally tapering, bidentate and spinulated, aristae reaching beyond level of distal tooth, chaetae progressively stouter and more conspicuously bidentate towards posterior body ( Fig. 3 E–F); ventral simple chaetae only present on posterior body, bidentate, smooth or with short subdistal spines ( Fig. 3 G). Anterior parapodia with up to 3 aciculae each, distally inflated and slightly oblique, with apparently hollow tips ( Fig. 3 H); single acicula per parapodium from midbody onwards, similar in shape to those of anterior body chaetigers, but progressively stouter ( Fig. 3 I). Pygidium with 1 pair of elongate anal cirri as long as median antenna. Pharynx through 3–4 chaetigers, with conical tooth close to anterior border; proventricle extending for ~3 chaetigers, with ~16 rows of muscle cells ( Fig. 3 A).

Remarks. Brazilian specimens have longer blades of spiniger-like chaetae, up to 80 µm long, similar to those of specimens from the Gulf of México and Florida ( San Martín 1991), and Bay of Biscay ( San Martín 2003), while Australian specimens have spiniger-like chaetae with shorter blades, up to 58 µm long ( San Martín 2005). Furthermore, the specimens herein analysed have the proventricle extending through 3 chaetigers, while specimens from other localities have a shorter proventricle, extending through 2 chaetigers ( San Martín 1991, 2005). The wide distribution and bathymetric range of this species, together with the discrepancies between descriptions of specimens from different localities, may indicate that this is in fact a complex of sibling species. Although already informally recorded in Brazil ( Fukuda 2010; Barroso 2011), this is the first formal report of this species to Brazilian waters.

Geographic distribution and bathymetric range. Atlantic Ocean—USA, Florida, 188 m deep (type locality) ( San Martín 1991) ; Gulf of México, 34–106 m deep ( Uebelacker 1984) ; Bay of Biscay , 1000 m deep ( San Martín et al. 1996); Angola Basin, 3964–5497 m deep ( Böggemann & Purschke 2005; Böggemann 2009). Indian Ocean— Australia, Western Australia, 8 m deep ( San Martín 2005). Brazilian specimens were collected from 722–1353 m deep.

Figures

FIGURE 3. Parexogone wolfi. (A) anterior body, dorsal view; (B – D) compound chaetae, anterior, mid- and posterior body chaetigers, respectively; (E – F) dorsal simple chaetae, anterior and posterior body chaetigers, respectively; (G) ventral simple chaeta; (H – I) aciculae, anterior and posterior body chaetigers, respectively; SEM: (J) anterior end, right lateral view; (K) spiniger-like chaeta, midbody chaetiger; (L) falcigers, midbody chaetiger.