Chone quebecensis, Tovar-Hernández, 2007

Tovar-Hernández, María Ana, 2007, Revision of Chone Krøyer, 1856 (Polychaeta: Sabellidae) from North America and descriptions of four new species, Journal of Natural History 41 (9 - 12), pp. 511-566 : 548-553

Chone quebecensis n. sp.

( Figures 13–15 , 19C )

Material examined

Type material. Quebec [ CMN 1989-0394 ], holotype , 13 paratypes; [ ECOSUR 0074 ] , four paratypes (two covered in gold for SEM): Saint Lawrence estuary, off Point Mitis, Sta. B 610-7IL-152D, 37 m, coll. Rafat MASSAD, 9 July 1971. Topotypes [ CMN 1989-0384 ], off Trois Pistols, Sta. B 130-70F-11D, 33 m, coll. Rafat MASSAD, 22 June 1970 (6). [ CMN 1989-0391 ], off Grandes Beyoeromes, Sta. B 94-15, 70L, 274 m, coll. Rafat MASSAD, 30 July 1970 (6). [ CMN 1989-0386 ], off Trois Pistols, Sta. B 167-70P-86D, 165 m, coll. Rafat MASSAD, 21 August 1970 (30). [ CMN 1989- 0390 ], off Point au Pire, Sta. B 527-71H-57D, 220 m, coll. Rafat MASSAD, 17 June 1971 (12). [ CMN 1989-0393 ], off St. Simon, Sta. B 247 71I-81D, 282 m, coll. Rafat MASSAD, 22 June 1971 (3). [ CMN 1989-0392 ], off Grandes Beyoeromes, Sta. B 92-7, 71I-83D, 357 m, coll. Rafat MASSAD, 23 June 1971 (2). [ CMN 1989-0385 , 10 ], off Trois Pistols, Sta. BI 63-7IL-121D, 115 m, coll. Rafat MASSAD, 6 July 1971 (10). [ CMN 1989-0387 ], off Point au Pire , Sta. B 504-71L-164B, 15 m, coll. Rafat MASSAD, 9 July 1971 (2) .

Non-type material. Labrador Sea [ ZMUC-POL-1758], ‘‘ Ingolf’ ’, Sta. 38., 59 ° 129N, 51 ° 059W, 3521 m, 30 July 1895 (1) material cited by Wessenberg-Lund (1950) as C. infundibuliformis . Nova Scotia [ CMN 1983-0165 ], Cape Breton, Bras d’Or Lake , St. Andrews Channel , Sta. CBNID, 60–120 m, 46 ° 38.59N, 60 ° 38.59W, coll. NMNS 121 Expedition, 1 July 1981 (22) . [ CMN 1983-01 ], Bras d’Or Lake, Saint Andrews Channel, Sta. CBNID, 60–120 m, 46 ° 359N, 60 ° 38.59W, coll. NMNS 121 Expedition, 1 July 1981 (1).

Additional material. Chone bimaculata Banse and Nichols, 1968 [USNM 36280, paratypes; 36281, paratype]. Chone ecaudata ( Moore, 1923) [USNM 17319, holotype, 58970, paratype]. Chone letterstedti ( Kinberg, 1867) [SMNH 576, holotype]. Chone perkinsi Tovar- Hernández, 2005 [FSBC I 66735, holotype].

Description (in parentheses variation observed in paratypes)

Colour, body shape, and size. Body and base of the branchial crown cream coloured. Trunk cylindrical ( Figure 13B, C ), posterior abdomen depressed latero-ventrally ( Figure 13G ). Body length 14 mm (4.1–16), width 1.3 mm (0.3–1.2). Tubes unknown.

Branchial lobes and branchial crown. Insertion of the branchial lobes (bl) exposed beyond collar ( Figure 13A, B ). Branchial crown length 7 mm (6–7). Radioles: 10 pairs (8–13). Radioles with median pinnules three times longer than more proximal pinnules. Radiolar tips long ( Figure 13E ). The palmate membrane extends to three-quarters the length of branchial crown. Lateral flanges broad ( Figure 13E ). Dorsal lips three times longer than wide, erect, without mid-rib. Dorsal pinnular appendages: one to three short pairs, united by a palmate membrane. Ventral lips rounded, as long as wide, about one-quarter the length of dorsal lips. Ventral radiolar appendages: one to three pairs, the inner one as long as three-quarters the length of branchial crown, the remainder about one-quarter the length of branchial crown.

Peristomium . Anterior peristomial ring lobe exposed beyond collar ( Figure 13B–D ), distally bilobed ( Figure 13D, F ). Posterior peristomial ring collar: antero-dorsal margin deeply incised, forming two well-developed dorsal pockets ( Figure 13A ), two dorsal, oval glandular shields (ogs) ( Figure 13A, B ), entire length of mid-dorsal collar margins forms a narrow gap ( Figure 13A ); lateral and ventral margins entire ( Figure 13C, D ); ventral margin slightly higher than dorsal ( Figure 13B, C ). Ventral shield of collar swollen, horseshoe-shaped, two times wider than long ( Figure 13D ). Ratio of posterior peristomial ring collar length versus chaetiger 2 length, in lateral view: 2:1.

Thorax. Chaetiger 1: two groups of four to six elongate, narrowly hooded chaetae. Chaetigers 2–8: notopodia—two irregular rows of four to five elongate, narrowly hooded chaetae; one anterior row with four to five bayonet chaetae ( Figures 13I , 14D, F ); two posterior rows with five symmetrical, paleate chaetae with long mucro ( Figures 13J–L , 14D, E ); neuropodia—one row of 8–13 acicular uncini per torus, main fang surmounted by four rows of teeth equal in size, occupying half the length of main fang ( Figures 13H , 14A ). Pre- and post-chaetal lobes well developed. Broad glandular, columnar epithelium (gce), swollen in ventral thoracic segments ( Figure 19C ). Broad glandular ridge on chaetiger 2, occupying half of the epithelium in longitudinal section ( Figure 19C ).

Abdomen. Abdominal segments: 46 (42–46). Anterior segments: two transverse rows of five to six elongate, narrowly hooded chaetae ( Figure 13M, V ), chaetae from upper row half as long as chaetae in lower row ( Figure 14G ); 10–12 uncini per torus, older (dorsalmost) and younger uncini (ventralmost) with the main fang surmounted by six regular rows of teeth in frontal view, equal in size, occupying three-quarters the length of main fang ( Figure 14B ), main fang not extending beyond breast ( Figure 14O ), breast rectangular. Posterior segments: one or two very elongate, narrowly hooded chaetae, 25% longer than in anterior segments ( Figure 14H ), making a small angle with the shaft at the base of the hood ( Figure 13N, U ); five to eight modified uncini per torus with the main fang surmounted by six to seven regular vertical rows of teeth equal in size ( Figure 14C ), occupying threequarters the length of main fang, older (dorsalmost) uncini smaller than younger uncini (ventralmost), main fang not extending beyond breast, breast rectangular. Ventral, glandular, whitish band on posterior abdomen (gb) ( Figure 13G ). Pygidium with triangular posterior margin ( Figure 13G ).

Gametes. Females with oocytes polyhedron-shaped in thorax and abdomen ( Figure 15B ), diameter 37.5–56.25 mm. Sperm in posterior abdominal chaetigers, spermatozoa rectangular nucleus (two times longer than wide), acrosome sucking-shaped (occupying one-quarter the length of nucleus) and two small, rounded mitochondria.

Methyl green staining. Anterior end of the ventral shield of collar not coloured, posterior end dark. Dorsally, there is no colour in collar, chaetigers 1 and 2; then each segment is divided into four dark rectangles by the presence of the faecal groove, inter-segmental and intra-notochaetal and neurochaetal grooves. Ventrally, each segment has a median, longitudinal dark band; lateral sides are coloured uniformly. Laterally, the collar has two large, rectangular spots ( Figure 13C ). Pygidium stays darker for several days.

Histology. The ventral, posterior abdominal glandular band (gb) in Chone quebecensis n. sp. is a complete whitish band in preserved material ( Figure 13G ), pink with haematoxylin–eosin ( Figure 15A ). This structure is located in a mid-ventral transition zone on the columnar epithelium ( Figure 15A, C, E, F ), and composed of strongly differentiated acidophil glandular cells (ag), tubular-shaped with granulose secretions ( Figure 15F ). The glandular columnar epithelium (gce) has large, rectangular cells, covered by cuticle (cu) ( Figure 15E ). Abdomen is composed of two ventral (vplm) and two dorsal packages of longitudinal muscle (dplm) ( Figure 15A, D ); the coelom is filled with oocytes (oo) and yolk (y) ( Figure 15B ).

Remarks

Chone quebecensis n. sp. is unique among Chone species in having (1) the ventral margin of anterior peristomial ring lobe distally bilobed; (2) two peristomial, dorsal glandular shields; (3) a ventral, longitudinal glandular band on the posterior part of abdomen; and (4) spermatozoa with rectangular nucleus (two times longer than wide), head suckershaped and two small, rounded mitochondria. The bilobed condition of the anterior peristomial ring lobe in Chone quebecensis n. sp. is common in species of Amphicorina Claparède, 1864 (in which it could be minutely bilobed or trilobed), and also in C. bimaculata and C. sp. 3 Fitzhugh, 2002 (bilobed in both). However, C. quebecensis n. sp. is easily distinguished from C. bimaculata and C. sp. 3 by having two peristomial, dorsal glandular shields and a ventral, longitudinal glandular band on the posterior part of abdomen.

Chone quebecensis n. sp., C. albocincta , and C. perkinsi have the glandular ridge on chaetiger 2 broad on one side: broad ventrally in C. quebecensis n. sp. and C. albocincta , and broad dorsally in C. perkinsi . Paleate chaetae with long mucro in C. quebecensis sp. nov. and C. perkinsi , with medium-sized mucro in C. albocincta . C. perkinsi has radioles with five to six dark brown bands, each band constituted by a variable number of bright, brownish spots surrounding the cells of the branchial skeleton; these bands are absent in C. quebecensis n. sp. Branchial lobes are exposed beyond the collar in C. quebecensis n. sp., and not exposed in C. perkinsi .

Chone quebecensis n. sp. and C. letterstedti have the antero-dorsal margin of the posterior peristomial ring collar deeply incised. Chone quebecensis n. sp. has long radiolar tips (short in C. letterstedti ); narrow flanges (broad in C. letterstedti ); posterior abdominal uncini modified (not modified in C. letterstedti ); and a posterior dorso-ventral abdominal depression (absent in C. letterstedti ).

Etymology

The specific epithet refers to the collecting and distribution zone.

Figures

Figure 13. Chone quebecensis n. sp. (A) Anterior end, dorsal view; (B) same, lateral view, collar reflexed; (C) same, lateral view, collar not reflexed; (D) same, ventral view; (E) radiolar tip; (F) anterior peristomial ring lobe; (G) posterior abdomen, ventro-lateral view; (H) thoracic uncinus; (I) bayonet chaeta; (J–L) paleate chaetae; (M, V) elongate narrowly hooded chaetae from anterior abdomen; (N, U) modified, elongate narrowly hooded chaetae from posterior abdomen; (O) anterior abdominal uncinus; (P–T) modified, posterior abdominal uncini. (A–B, E– V) [CMN 1989-0304, paratype]; (C, D) [CMN 1989-0394, holotype].

Figure 14. Chone quebecensis n. sp. (A) Thoracic uncini; (B) anterior abdominal uncini; (C) posterior abdominal uncini; (D) thoracic chaetiger; (E) paleate chaeta; (F) bayonet chaetae; (G) anterior abdominal chaetiger; (H) posterior abdominal chaetiger. [ECOSUR 0074, paratype]. (A, B, D, G, H) SEM UNAM; (C, E, F) SEM ECOSUR. Scale bars: 5 mm (A, B, E); 50 mm (D, G, H).

Figure 15. Chone quebecensis n. sp., transversal sections from posterior abdomen. (A) Panoramic view; (B) oocytes and yolk; (C) gut and glandular, abdominal band; (D) ventral package of longitudinal muscle; (E) glandular, columnar epithelium; (F) glandular, abdominal band. [CMN 1983-0165, topotype]. Scale bars: 200 mm (A); 50 mm (B); 100 mm (C); 56 mm (D); 12.5 mm (E, F).

Figure 19. Thoracic transversal sections. (A) Chone ecaudata; (B) Chone mollis; (C) Chone quebecensis n. sp. (A) [LACM-AHF LH02-1205]; (B) [LACM-AHF, Han Lee]; (C) [CMN 1989-0385].