Exogone dispar ( Webster, 1879 )

Exogone dispar ( Webster, 1879)

( Figures 9–11 View FIGURE 9 View FIGURE 10 View FIGURE 11 )

Paedophyllax dispar Webster, 1879: 223 –224, pl. 4, fig. 49, pl. 5, figs 50–55

Exogone dispar . Westheide 1974: 298 –301, figs 48–49; Perkins 1981: 1090 –1091; Uebelacker 1984: 30 –43, fig. 30–36; Campoy 1982: 290, pl. 21; San Martín 1984: 221 –224, pl. 52.

Exogone (Exogone) dispar . San Martín 1991: 729 –730; 2003: 274–276, figs 149–150; 2005: 137–138, figs 81 F, 85; Ruíz- Ramírez & Salazar-Vallejo 2001: 127, fig. 3 (45–54); Fukuda 2010: 126 –129, fig. 35.

Material examined. Project ‘ REVIZEE ’: State of Rio de Janeiro: 21 º 51 'S 40 º07'W, 110 m: 2 specimens, coll. 0 2 March 1998; 23 º06'S 42 º 24 'W, 93 m: 10 specimens, coll. 16 February 1998; 23 º 20 'S 41 º 22 'W, 110 m: 12 specimens, coll. 28 February 1998; 23 º 26 'S 41 º 15 'W, 145 m: 1 specimen, coll. 27 February 1998; 24 º02'S 43 º 30 'W, 147 m: 18 specimens, coll. 14 February 1998. State of São Paulo: 24 º07'S 45 º 51 'W, 147 m: 70 specimens, coll. 0 9 January 1998; 24 º07'S 44 º 42 'W, 101 m: 21 specimens, coll. 11 January 1998; 25 º 11 'S 47 º08'W, 157 m: 40 specimens, coll. 16 December 1997; 25 º 17 'S 46 º 55 'W, 60 m: 1 specimen, coll. 16 December 1997; 25 ° 22 'S 46 ° 47 'W, 70 m: 5 specimens, coll. 16 December 1997. State of Paraná: 27 º07'S 47 º 44 'W, 102 m: 1 specimen, coll. 13 March 1998. State of Santa Catarina: 28 º 41 'S 48 º 18 'W, 104 m: 1 specimen, coll. 22.March 1998. Project ‘ BIOTA ’: State of São Paulo: Ubatuba, sublittoral, 23 ° 24 ' 366 ''S 45 ° 51 ' 431 ''W, 16.6 m: 1 specimen, coll. 17 November 2001; 23 ° 25 ' 663 ''S 44 ° 46 ' 570 ''W, 35 m: 1 specimen, coll. 10 April 2001; 23 ° 25 ' 785 ''S 44 ° 46 ' 738 ''W, 35 m: 1 specimen, coll. 17 March 2001; 23 ° 32 ' 765 ''S 44 ° 44 ' 380 ''W, 43.8 m: 5 specimens, coll. 10 June 2001. Caraguatatuba, Praia de Martim de Sá (23 ° 37 ' 34 ''S 45 ° 22 ' 31 ''W), on rocky shore, intertidal: 1 specimen, coll. 13 March 2001; on Dyctiota sp.: 1 specimen, coll. 16 March 2001. São Sebastião, sublittoral, 23 ° 44 ' 844 ''S 45 °02' 451 ''W, 45 m: 2 specimens, coll. 13 February 2001; 23 ° 56 ' 373 ''S 45 ° 27 '080''W, 44.6 m: 4 specimens, coll. 15 December 2001; 23 ° 56 ' 497 ''S 45 ° 28 ' 339 ''W, 45.1 m: 2 specimens, coll. 16 May 2001. Project ‘ Poly-Phytal ’: State of Espírito Santo: Vitória, Praia da Direita, Ilha do Boi (20 ° 18 'S 40 ° 17 'W), rocky shore, intertidal, on Arthrocardia gardnerii : 2 specimens ( MZUSP 1321), coll. 26 May 2005; 2 specimens ( MZUSP 1322), coll. 0 1 November 2005; on Centroceras clavulatum : 2 specimens ( MZUSP 1320), coll. 0 1 November 2005; on Hypnea musciformis : 1 specimen ( MZUSP 1323), coll. 0 1 November 2005. Project ‘ HABITATS ’: State of Rio de Janeiro (Campos Basin), Van Veen grab; 21 ° 22 ' 58 "S 40 ° 19 ' 41 "W, 53 m: 2 specimens, coll. 0 5 March 2009, 3 specimens, coll. 0 6 March 2009, 4 specimens, coll. 21 July 2009; 21 ° 23 ' 2 "S 40 ° 15 ' 9 "W, 145 m: 1 specimen, coll. 0 6 March 2009; 21 ° 59 ' 4 "S 40 ° 25 ' 11 "W, 52 m: 4 specimens, coll. 25 February 2009, 2 specimens, coll. 0 6 July 2009; 22 ° 1 ' 9 "S 40 ° 31 ' 55 "W, 49 m: 2 specimens, coll. 24 July 2009; 22 ° 3 ' 41 "S 40 ° 24 ' 9 "W, 55 m: 27 specimens, coll. 25 February 2009, 1 specimen, coll. 0 6 July 2009; 22 ° 4 ' 14 "S 40 ° 6 ' 59 "W, 91 m: 1 specimen, coll. 25 February 2009; 22 ° 6 ' 55 "S 40 ° 38 ' 59 "W, 53 m: 42 specimens, coll. 26 February 2009, 12 specimens, coll. 17 July 2009; 22 ° 7 ' 43 "S 40 ° 18 ' 46 "W, 73 m: 1 specimen, coll. 24 February 2009; 22 ° 12 ' 17 "S 40 ° 14 ' 39 "W, 96 m: 1 specimen, coll. 15 March 2009, 2 specimens, coll. 24 July 2009; 22 ° 12 ' 53 "S 40 ° 51 ' 13 "W, 52 m: 23 specimens, coll. 26 February 2009, 2 specimens, coll. 17 July 2009; 22 ° 17 ' 42 "S 40 ° 26 ' 59 "W, 104 m: 1 specimen, coll. 23 February 2009; 22 ° 37 ' 35 "S 41 ° 21 ' 51 "W, 53 m: 4 specimens, coll. 27 February 2009; 22 ° 41 ' 46 "S 41 ° 53 ' 45 "W, 29 m: 1 specimen, coll. 16 March 2009, 1 specimen, coll. 12 July 2009; 22 ° 45 ' 49 "S 41 ° 45 ' 33 "W, 53 m: 3 specimens, coll. 16 July 2009; 22 ° 46 ' 54 "S 41 ° 3 ' 33 "W, 78 m: 8 specimens, coll. 28 February 2009; 22 ° 55 ' 8 "S 42 °0' 49 "W, 29 m: 6 specimens, coll. 28 February 2009, 5 specimens, coll. 15 July 2009; 22 ° 59 ' 47 "S 41 ° 21 ' 7 "W, 77 m: 2 specimens, coll. 21 February 2009; 23 ° 6 ' 51-58 "S 41 ° 55 - 53 'W, 111 m: 4 specimens, coll. 0 1 March 2009, 9 specimens, coll. 16 March 2009. Project ‘ BioPol-NE ’: State of Paraíba: Mataraca, Barra de Camaratuba (06º 36 'S 34 º 57 'W), intertidal: 2 specimens ( MZUSP 2095), coll. 12 August 2010. Baía da Traição, Praia do Farol (06º 41 'S 34 º 55 'W), intertidal: 6 specimens ( MZUSP 2086), coll. 0 9 August 2010. Rio Tinto, Barra de Mamanguape (06º 45 'S 34 º 55 'W), intertidal: 2 specimens ( MZUSP 1327), coll. 11 August 2010. Cabedelo, Píer de Cabedelo (06º 58 'S 34 º 50 'W), intertidal: 2 specimens, coll. 12 February 2009. João Pessoa, Cabo Branco (07o08'S 34 o 47 'W), intertidal: 4 specimens ( MZUSP 1326), coll. 0 9 February 2009, 7 specimens ( MZUSP 1328), coll. 0 2 February 2010; in Tedania sp.: 1 specimen, coll. 0 9 February 2009; Recife do Picãozinho (07° 4.243 'S 34 ° 49.291 'W), intertidal: 1 specimen ( MZUSP 1325), coll. 15 September 2009. Conde, Praia de Carapibus (07º 17 'S 34 º 48 'W), intertidal, in rhodoliths: 1 specimen ( MZUSP 2092); on algae: 3 specimens coll. 0 9 February 2009; Praia do Coqueirinho (07º 18 'S 34 º 47 'W), intertidal: 2 specimens ( MZUSP 2087), coll. 28 August 2011; Praia de Jacumã (07º 14 'S 34 º 47 'W), intertidal: 6 specimens ( MZUSP 2094), coll. 29 January 2010; Praia de Tabatinga (07° 19.297 'S 34 ° 47.862 'W), intertidal: 2 specimens ( MZUSP 2088), coll. 17 September 2012, 2 specimens ( MZUSP 2093), coll. 0 1 September 2011; Praia de Tambaba (07° 21 'S 34 ° 47 'W), 4 specimens ( MZUSP 2091), coll. 30 August 2011. Pitimbu, Farol de Pitimbu (7 ° 28.362 'S 34 º 47 'W), 1 m: 2 specimens ( MZUSP 2090), coll. 18 September 2012. State of Pernambuco, Goiana, Pontas de Pedra (07° 37 'S 34 ° 48 'W), 16 specimens ( MZUSP 2085), coll. 13 December 2012. Ilha de Itamaracá, Recifes de Itamaracá, (07° 43.944 'S 34 ° 49.200 'W), 1 m: 2 specimens ( MZUSP 2089), coll. 15 December 2012.

Description. Body thin, elongated, longest specimens ca. 5.6 mm long and 0.2 mm wide, with up to 45 chaetigers. Palps triangular, distally rounded ( Figs 9 View FIGURE 9 A, 10 A–C), almost totally fused, with conspicuous line of fusion and distal notch ( Fig. 9 View FIGURE 9 A). Prostomium pentagonal to ovate, slightly shorter than palps, with two pairs of eyes in trapezoidal arrangement ( Fig. 9 View FIGURE 9 A); anterior eyespots absent; antennae inserted close to each other in nearly transverse row, median antenna inserted anteriorly to anterior pair of eyes, elongated, shorter than palps, subdistally inflated with tapered tip ( Figs 9 View FIGURE 9 A, 10 A, G); lateral antennae inserted slightly anterior to median antenna, ovate to papilliform, ca. ¼–½ length of median antenna ( Figs 9 View FIGURE 9 A, 10 A, G). Ciliated nuchal organs located dorsolaterally between prostomium and peristomium ( Fig. 10 View FIGURE 10 A, G–H). Peristomium similar in length to following chaetigers, sometimes covering posterior part of prostomium, including posterior pair of eyes; peristomial cirri similar to lateral antennae but smaller ( Figs 9 View FIGURE 9 A, 10 A, B). Dorsal cirri ovate, slightly larger than peristomial cirri, progressively longer posteriorwards, present on all chaetigers ( Figs 9 View FIGURE 9 A, 10 A). Ventral cirri similar to dorsal cirri but shorter, ca. 2 / 3 length of parapodial lobes ( Fig. 10 View FIGURE 10 B). Parapodial lobes blunt ( Fig. 10 View FIGURE 10 D); anterior parapodia with 1–3 spiniger-like chaetae and 6–8 falcigers each, midbody parapodia with single spiniger-like chaeta and 3–4 falcigers each ( Fig. 11 View FIGURE 11 D), posterior parapodia with single spiniger-like chaeta and 2–3 falcigers each ( Fig. 11 View FIGURE 11 F). Shafts of anterior spiniger-like chaetae with conspicuous spines, posterior spines shorter ( Figs 9 View FIGURE 9 B, 11 C); shafts of spiniger-like chaetae on midbody with distal longitudinal lines forming grooves ( Figs 9 View FIGURE 9 C–D, 11 D); all blades with short spines ( Figs 9 View FIGURE 9 B, 11 C), blades 45 – 22 µm long on anterior body, 50 – 25 µm on midbody and 32 – 15 µm on posterior. Shafts of anterior falcigers subdistally enlarged and spinulated ( Figs 9 View FIGURE 9 B, 11 A–B), shafts of posterior falcigers also subdistally enlarged, but with fewer spines, shafts of falcigers on mid- and posterior body with distal longitudinal lines forming grooves ( Figs 9 View FIGURE 9 C–D, 11 D–E). Blades of falcigers spinulated and bidentate, subdistal tooth larger ( Figs 9 View FIGURE 9 B–D, 11 A–F); blades with dorsoventral gradation in length, 10 – 3 µm long on anterior, 8 – 3 µm long midbody, and 5 – 2 µm long on posterior body. Dorsal simple chaetae present on all chaetigers, sigmoid, subdistally spinulated, with acute tip, stouter posteriorwards ( Figs 9 View FIGURE 9 E–F, 11 D, F, H); ventral simple chaetae present only on posterior chaetigers, sigmoid, bidentate, subdistal tooth larger ( Figs 9 View FIGURE 9 G, 11 G). Anterior parapodia with up to two aciculae each, one straight, with acute tip, other slightly bent subdistally, with inflated, rounded tip ( Fig. 9 View FIGURE 9 H); midbody and posterior parapodia with single acicula each, of the second type, stouter posteriorwards ( Fig. 9 View FIGURE 9 I). Ciliated pygidium with a pair of thin, elongate anal cirri ( Fig. 10 View FIGURE 10 E–F). Pharynx through 4–5 segments, tooth at anterior border ( Figs 9 View FIGURE 9 A, 10 B–C); anterior margin of pharynx surrounded by papillae and fringe of cilia ( Fig. 10 View FIGURE 10 B–C); proventricle extending for 2–5 chaetigers ( Fig. 9 View FIGURE 9 A), with ca. 22 rows of muscle cells ( Fig. 9 View FIGURE 9 A).

Remarks. Exogone dispar is similar to the sympatric E. breviantennata and E. africana but differs from both in having an elongated median antenna. Exogone rolani also share some characters with E. dispar (see 'Remarks' of the former species). Exogone arenosa , E. gigas sp. n. and E. lourei , which also occur along the Brazillian coast, all have a triangular process on the shafts of the spiniger-like chaetae of chaetiger 2, which is absent in E. dispar . More detailed comparisons between E. dispar and other species in this genus are provided by Perkins (1981) and San Martín (1991, 2003, 2005), among several others.

Brazilian specimens of E. dispar differ from Australian ones by having longer blades of the spiniger-like chaetae, 50 – 22 µm vs. 29 – 28 µm, as in Australian material ( San Martín 2005).

Type locality. Northampton, Virginia ( USA, Atlantic Ocean).

Distribution. Atlantic Ocean: USA, Mexico, Panamá, Brazil (Paraíba, Pernambuco, Bahia, Espírito Santo, São Paulo), South Africa; North Sea: Skagerrak; Mediterranean Sea: Iberian Peninsula, Italy; Caribbean Sea: Cuba, Trinidad and Tobago. Pacific Ocean: Mexico (Baja California), Galápagos Islands, China, Japan. Indian Ocean: Australia (Western Australia). From the intertidal zone to ca. 157 m deep.