Chone

Tovar-Hernández, María Ana, 2007, On some species of Chone Krøyer, 1856 (Polychaeta: Sabellidae) from world-wide localities, Zootaxa 1518, pp. 31-68 : 58-60

Chone sp. British Virgin Islands

Figures 16

Material examined. Non-type material. British Virgin Islands [ LACM – AHF] AF00–05 White Bay, 2 finger reefs closest to beach house, Coll. K. Fitzhugh, July 4, 2000, 40 m offshore, scraping of sand and sparse filamentous algae ( Ceramium , Polysiphonia ) on flat coral boulder, 1 m (1). AF00–12 Long Point, 70 m SE of dock, above crest of reef, more protected area in a furrow on the bottom, covered with fine algae growing on small pebbles, Coll. T. Zimmerman and G. Hendler, hand, July 5, 2000, 18° 29.15’ N, 64° 34.97’ W, 0.6–0.8 m (1). Mexican Caribbean [ECOSUR] Bajo Pepito, Isla Mujeres, Quintana Roo, Mexico; in Stypopodium zonata, Coll. M. Díaz , February 1997 (2); February 5, 1997 (3); April 1997 (9); in Sargassum vulgaris , May 1997 (1); July 1997 (4). Xcayal, lighthouse, B 110, November 4, 1990 (2). [ LACM – AHF] LH01–665, Isla Contoy, South point, West side, green felt on coral rubble, rock, 0.33 m, Coll. L. Harris, March 0 2, 2001 (2). Bahamas [ LACM – AHF] LH03–231, Sta. 45, Exuma Cays, Basil Minn’s Cave, marine entrance pool, algae and sediment scooped up from bottom, strong H2S odor from black silt, January 11, 2003 (1). LH03–157, Sta. 31, Exuma Cays, Stocking Cay, 6 m south of entrance to Mystery Cave, Coll. T. Haney, January 9, 2003, 2 m (2).

Additional material. Chone americana Day, 1973 [ USNM 43137, paratype]. Chone filicaudata Southern, 1914 [ BMNH 1914.12.12.25, syntype].

Description. Colour, body shape, and size. Body cream coloured. Trunk cylindrical, posterior abdomen slightly depressed dorso-ventrally. Body length 3–6 mm, width 0.5–1.5 mm. Tubes constructed with fine sand.

Branchial lobes and branchial crown. Insertion of the branchial lobes exposed beyond collar. Branchial crown length 1.2–2.3 mm. Radioles: 5–6 pairs. All pinnules long. Radiolar tips medium-sized ( Fig. 16 A). Palmate membrane extends a half the length of the branchial crown ( Fig. 16 A). Lateral flanges broad. Dorsal lips three times longer than wide, erect, without a discernable longitudinal ridge. Ventral lips broad, as long as wide, about one half of the dorsal lips length. Ventral radiolar appendages: two pairs, the inner one about one quarter the length of the branchial crown length ( Fig. 16 A), others about one half of the branchial crown length.

Peristomium . Anterior peristomial ring lobe exposed beyond collar, distally entire, triangular ( Fig. 16 A). Antero-dorsal, lateral, and ventral margins of posterior peristomial ring collar entire, ventral slightly higher than dorsal ( Figs 16 A); entire length of mid-dorsal collar margins forms a narrow gap, dorsal pockets well developed. Ventral collar shield swollen, horseshoe-shaped, two times wider than long. Ratio of posterior peristomial ring collar length versus chaetiger 2 length, in lateral view: 1.5:1. Otoliths in peristomium .

Thorax. Elongate, narrowly hooded chaetae; narrowly hooded bayonet chaetae; symmetrical; paleate chaetae with medium-length mucro. One row of acicular uncini, second tooth enlarged, located offset the midline, dentition covering three quarters of the main fang length ( Figs 16 C–D). Glandular ridge on chaetiger 2: narrow.

Abdomen. Abdominal segments: 23. Anterior segments: 3–4 elongate, narrowly hooded chaetae, upper row chaetae half as long as lower row ones; uncini with the main fang surmounted by four irregular rows of unequal in size teeth (basal median tooth of basal row enlarged), occupying one half of the main fang length ( Fig. 16 E), older (dorsal most) uncini smaller than younger ones (ventral most), main fang not extending beyond breast, breast rectangular. Posterior segments: 1–2 very long, narrowly hooded chaetae ( Figs 16 B, F), 25% longer than in anterior segments; modified uncini with the main fang surmounted by eight regular rows of teeth equal in size, occupying three quarters of the main fang length ( Fig. 16 G), older (dorsal most) uncini smaller than younger uncini (ventral most), main fang not extending beyond breast, breast rectangular. Pygidium with triangular posterior margin, and short cirrus ( Fig. 13 B).

Gametes. Females with oocytes (oo) in anterior thoracic chaetigers, diameter 0.75– 0.15 mm.

Methyl green staining. Anterior end of the ventral collar shield not coloured, posterior end dark. Body uniformly coloured dorsal and ventrally.

Remarks. Chone americana and C. sp. British Virgin Islands are unique among Western Atlantic Chone species by having a pygidial cirrus: C. americana differs from C. sp. British Virgin Islands because it has long radiolar tips (short in C. sp. British Virgin Islands), anterior peristomial ring lobe and branchial lobes not exposed above collar (both exposed in C. sp. British Virgin Islands), and sperm with barrel-shaped nucleus (spherical in C. sp. British Virgin Islands). Another species with pygidial cirrus is C. filicaudata from Ireland, but this species have the anterior peristomial ring lobe incised, while it is entire in C. americana . The anterior abdominal uncini in Chone sp. British Virgin Islands and C. americana have four irregular rows of unequal in size teeth (basal median tooth of basal row enlarged), occupying one half of the main fang length.

Figures

FIGURE 13. Chone paracincta. (A) Anterior end, lateral view; (B) same, dorsal view; (C) same, ventral view; (D) posterior end. (A – C) Methyl green staining. (A – D) [ZMH P – 15209, syntype].

FIGURE 16. Chone sp. British Virgin Islands. (A) Branchial crown, ventral view; (B) posterior end, ventral view; (C – D) thoracic uncini; (E) anterior abdominal uncini; (F) very elongate narrowly hooded chaetae from posterior abdomen; (G) posterior abdominal uncini. (A – G) [ECOSUR]. Scale bars: (A) 500 m; (B) 100 m; (C – D) 5 m; (E) 3.5 m; (F) 20 m; (G) 5 m. (A – D, G) [SEM UNAM]; (E – F) [SEM ECOSUR].