Opisthodonta russelli

Fukuda, Marcelo V., Nogueira, João M. M. & Martín, Guillermo San, 2015, Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species, Zootaxa 3936 (4), pp. 507-537 : 530-532

Opisthodonta russelli San Martín, López & Aguado, 2009, amended

Figures 14–16 ; Table 2

Opisthodonta russelli San Martín, López & Aguado, 2009: 1474 –1475, fig. 6. Opisthodonta sp. B. Uebelacker 1984: 30 -64–30-65, figs 30-57–30-58. Opisthodonta sp. 1. Fukuda 2010: 63 –66, fig. 17.

Material examined. Project ‘ REVIZEE ´. State of Rio de Janeiro— 23°09’S 40°56’W, 257 m: 1 spec. ( MZUSP 2442), 1 Mar 1998; 23°20’S 41°22’W, 110 m: 10 specs (1 spec., MZUSP 2439; 5 specs, MZUSP 2444; 1 spec., ZUEC-Pol 16093), 28 Feb 1998; 23°26’S 41°15’W, 146 m: 5 specs (1 spec., MZUSP 2440; 1 spec., ZUEC-Pol 16092; 2 specs, ZUEC-Pol 16173), 28 Feb 1998; 23°29’S 41°09’W, 266 m: 3 specs ( MZUSP 2446), 28 Feb 1998; 23°41’S 41°44’W, 149 m: 3 specs (ZUEC-POL 16172), 17 Feb 1998; 24°02’S 43°30’W, 147 m: 4 specs ( MZUSP 2445), 14 Feb 1998. State of São Paulo— 24°07’S 45°51’W, 147 m: 2 specs ( MZUSP 2443), 9 Jan 1998; 24°20’S 44°09’W, 258 m: 1 spec. (ZUEC-POL 16171), 10 Jan 1998.

Project ' Habitats '. 21°9'10"S 40°16'7"W, 101 m: 2 specs ( MZUSP 2426), 7 Mar 2009, and 2 specs ( MZUSP 2437; ZUEC-POL 16169), 21 Jul 2009; 21°11'1"S 40°28'28"W, 26 m: 1 spec. (ZUEC-POL 16168), 21 Jul 2009; 21°12'13"S 40°42'25"W, 15 m: 1 spec. ( MZUSP 2408), 7 Mar 2009; 21°14'15"S 40°14'8"W, 66 m: 2 specs ( MZUSP 2411), 8 Jul 2009; 21°23'3"S 40°15'10"W, 142 m: 3 specs ( MZUSP 2428; ZUEC-POL 16157), 6 Mar 2009, and 8 specs ( MZUSP 2438), 21 Jul 2009; 21°23'38"S 40°15'37"W, 88 m: 2 specs ( MZUSP 2436; ZUEC- POL 16170), 21 Jul 2009; 21°24'43"S 40°25'20"W, 32 m: 1 spec. (ZUEC-POL 16140), 20 Jul 2009; 21°34'12"S 40°25'32"W, 29 m: 1 spec. ( MZUSP 2406), 13 Mar 2009; 21°42'37"S 40°8'58"W, 147 m: 11 specs ( MZUSP 2427; ZUEC-POL 16156), 10 Mar 2009, and 23 specs ( MZUSP 2433; ZUEC-POL 16165), 7 Jul 2009; 21°42'53"S 40°10'15"W, 98 m: 1 spec. (ZUEC-POL 16155), 9 Mar 2009; 21°43'10"S 40°11'30"W, 72 m: 2 specs (ZUEC-POL 16164), 8 Jul 2009; 21°44'19"S 40°17'15"W, 50 m: 3 specs ( MZUSP 2432; ZUEC-POL 16163), 8 Jul 2009; 21°50'3"S 40°6'14"W, 469 m: 1 spec. ( MZUSP 2441), 28 Jun 2008; 21°59'4"S 40°25'10"W, 52 m: 1 spec. ( MZUSP 2424), 25 Feb 2009; 22°3'38"S 40°6'59"W, 90 m: 2 specs ( MZUSP 2431; ZUEC-POL 16162), 7 Jul 2009; 22°3'41"S 40°24'8"W, 56 m: 1 spec. ( MZUSP 2421; ZUEC-POL 16153), 25 Feb 2009; 22°3'45"S 40°9'59"W, 75 m: 2 specs ( MZUSP 2425), 25 Feb 2009; 22°6'20"S 40°43'41"W, 47 m: 1 spec. ( MZUSP 2409), 17 Jul 2009; 22°6'55"S 40°38'58"W, 53 m: 14 specs ( MZUSP 2417; ZUEC-POL 16150), 26 Feb 2009, and 4 specs ( MZUSP 2435; ZUEC-POL 16167), 17 Jul 2009; 22°8'9"S 40°27'27"W, 65 m: 1 spec. ( MZUSP 2418), 23 Feb 2009; 22°11'59"S 40°32'7"W, 68 m: 4 specs ( MZUSP 2407; ZUEC-POL 16138), 15 Mar 2009; 22°12'18"S 40°14'39"W, 97 m: 1 spec. (ZUEC-POL 16139), 15 Mar 2009; 22°12'37"S 40°13'18"W, 100 m: 10 specs ( MZUSP 2422; ZUEC- POL 16154), 24 Feb 2009, and 26 specs ( MZUSP 2430; ZUEC-POL 16160), 5 Jul 2009; 22°12'31"S 40°14'7"W, 97 m: 1 spec. (ZUEC-POL 16142), 24 Jul 2009; 22°12'52"S 40°51'12"W, 52 m: 1 spec. (ZUEC-POL 16146), 26 Feb 2009; 22°13'44"S 40°32'43"W, 70 m: 2 specs ( MZUSP 2410; ZUEC-POL 16141), 25 Jul 2009; 22°17'25"S 40°6'36"W, 143 m: 1 spec. ( MZUSP 2423), 24 Feb 2009, and 1 spec. (ZUEC-POL 16161), 5 Jul 2009; 22°17'42"S 40°26'59"W, 104 m: 5 specs ( MZUSP 2419; ZUEC-POL 16151), 23 Feb 2009, and 8 specs ( MZUSP 2429; ZUEC- POL 16158), 4 Jul 2009; 22°19'32"S 40°37'18"W, 75 m: 4 specs ( MZUSP 2414; ZUEC-POL 16147), 15 Mar 2009, and 5 specs ( MZUSP 2416; ZUEC-POL 16149), 4 Jul 2009; 22°23'20"S 40°34'56"W, 110 m: 22 specs ( MZUSP 2434), 25 Jul 2009; 22°23'38"S 40°20'42"W, 153 m: 4 specs ( MZUSP 2420; ZUEC-POL 16152), 23 Feb 2009, and 1 spec. (ZUEC-POL 16159), 4 Jul 2009; 22°46'54"S 41°3'33"W, 78 m: 1 spec. ( MZUSP 2412), 22 Feb 2009, and 1 spec. ( MZUSP 2415), 2 Jul 2009; 22°52'1"S 40°57'28"W, 92 m: 2 specs ( MZUSP 2413), 22 Feb 2009.

Additional material examined. Opisthodonta russelli— Venezuela, Parque Nacional Morrocoy, on Thalassia testudinum , 0.5 m: 7 specs (holotype, MNCN 16.01/6063; paratypes, MNCN 16.01/6064-6069). Opisthodonta sp. B sensu Uebelacker (1984) — USA, North Carolina, Beaufort (34°19'14"N 75°55'48"W), 130 m: 1 spec. ( USNM 51071), coll. J.H. Day, 0 6 Apr 1965, det. J.M. Uebelacker; Gulf of Mexico, Florida (29°47'59"N 86°09'28"W), 45 m: 1 spec. ( USNM 55824), coll. R/V Columbus Iselin, Jun 1975, id. J.M. Uebelacker.

Description. Medium-sized, fragile body, specimens examined mostly anterior fragments with few chaetigers after proventricle and without appendages; largest specimen examined (MZUSP 2495) 9.55 mm long, 0.84 mm wide, with 49 chaetigers ( Table 2 ); body without pigmentation patterns, dorsally scattered with tufts of cilia as short, transverse rows, at least on midbody ( Figs 15 A, C, E; 16D). Palps foliaceous, broader than prostomium, triangular ( Figs 14 A; 15A–D). Prostomium oval to subpentagonal, with 2 pairs of eyes in close trapezoidal arrangement and 1 pair of anterior eyespots ( Fig. 14 A); lateral antennae inserted in front of anterior pair of eyes, near anterior margin of prostomium, up to twice as long as combined length of prostomium and palps; median antenna inserted centrally, almost twice as long as lateral antennae; nuchal organs as dense row of cilia at posterior margin of prostomium, more conspicuous dorso-laterally ( Fig. 15 A, C–D). Peristomium shorter than anterior chaetigers; dorsal peristomial cirri as long as lateral antennae or slightly longer, ventral peristomial cirri 2/3 length of dorsal peristomial cirri. Anterior body dorsal cirri variable in length, shorter cirri slightly shorter than body width at corresponding chaetigers, longer cirri up to 3 times length of shorter cirri ( Figs 14 A; 15A, C); dorsal cirri progressively thinner towards posterior body, whip-shaped, nearly of same length as anterior body dorsal cirri; anterior body ventral cirri foliaceous, wide, partially fused to parapodial lobes, at least as long as parapodial lobes, with mamiliform tips ( Figs 15 B; 16A–B); ventral cirri progressively smaller, conical to ovate towards posterior body ( Figs 15 B; 16C). Antennae, peristomial and dorsal cirri throughout similar, long and slender, with conspicuous cirrophores ( Figs 14 A; 15A–D). Anterior body parapodia with 1–7 dorsalmost compound chaetae spiniger-like, with smooth shafts; blades long, basally inflated and distally inconspicuously bifid, 100–42 Μm long ( Fig. 14 B–C); spiniger-like chaetae absent from midbody chaetigers ( Fig. 15 A–C). Anterior body parapodia with ~20–32 falcigers each, decreasing to ~6–14 falcigers per parapodium from midbody; falcigers with weakly spinulated shafts ( Figs 14 B–D, F–G; 16E–I); blades bidentate, subdistal tooth larger than distal tooth; blades with dense spinulation forming a hood, translucent under optical microscopy, usually leaving uncovered only tips of teeth on anterior body and on dorsalmost chaetae of each parapodium throughout ( Figs 14 B–D; 16E–G), teeth more conspicuous from midbody ( Figs 14 F–G; 16H–I); blades of anterior body falcigers with dorsoventral gradation in length, 26–12 Μm long; posterior body falcigers of two different types: dorsalmost falcigers with distinctly heterogomph shafts, blades bidentate, subdistal tooth larger than distal tooth, with hood shorter than on anterior body falcigers, blades ~20–10 Μm long ( Fig. 14 F); ventralmost falcigers with shafts progressively shorter and stouter ventralwards, subtly heterogomph, blades bidentate, subdistal tooth larger than distal tooth, with more conspicuous difference in size between teeth, spinulation not forming hood ( Figs 14 G; 16H–I). Dorsal simple chaetae thin, capillary, apparently finely bidentate distally, absent on most specimens analysed; ventral simple chaetae not observed. Anterior body parapodia with 3–7 aciculae each, diminishing in number towards posterior body, posterior parapodia with 1–3 aciculae each; aciculae with tips sometimes protruding from parapodial lobes, distally rounded, with subdistal crown of short spines ( Fig. 14 E); aciculae progressively thinner towards posterior body. Pharynx long and wide, through 13–17 segments, with large, pyriform tooth with acute tip near midlength or slightly anteriorly, usually located laterally; proventricle wide, through 5–8 chaetigers, with ~30–35 muscle cell rows ( Fig. 14 A).

Remarks. The original description of O. russelli was based only on anterior fragments (San Martín et al. 2009). Thus, our description of mid- and posterior body characters (mostly from chaetae) is new for this species. A complete comparison with the most similar congeners may be found in San Martín et al. (2009).

Type locality. Venezuela—Morrocoy National Park (Atlantic Ocean).

Distribution. Atlantic Ocean: Venezuela; Belize. First record for the Brazilian coast.

Figures

FIGURE 14. Opisthodonta russelli. (A) anterior body, dorsal view; (B) chaetae, anterior body; (C) spiniger-like chaetae, anterior body; (D) falcigers, anterior body; (E) aciculae, anterior body; (F) dorsalmost falcigers, posterior body; (G) ventralmost falcigers, posterior body. Scale bars: A = 500 µm; B – C = 20 µm; D – G = 10 µm.

FIGURE 15. Opisthdonta russelli, SEM. (A), (C) anterior body, dorsal view; (B) anterior body, ventral view; (D) prostomium, dorsal view; (E) midbody, dorsal view. Scale bars: A – C = 200 µm; D = 50 µm; E = 100 µm.

FIGURE 16. Opisthodonta russelli, SEM. (A) anterior body parapodia, ventral view; (B) ventral cirri, anterior body; (C) posterior body parapodia, ventral view; (D) tufts of cilia on dorsum; (E) falciger, anterior body; (F) falcigers, midbody; (G) dorsalmost falciger, posterior body; (H), (I) ventralmost falcigers, posterior body. Scale bars: A = 100 µm; B = 50 µm; C = 25 µm; D = 10 µm; E = 2.5 µm; F = 5 µm; G – I = 2 µm.