Chone normani McIntosh, 1916

Tovar-Hernández, María Ana, 2007, On some species of Chone Krøyer, 1856 (Polychaeta: Sabellidae) from world-wide localities, Zootaxa 1518, pp. 31-68 : 50-52

Chone normani McIntosh, 1916

Figure 11

Chone normani McIntosh, 1916: 65 –67, Pl. 2, Figs 13–15 , Pl. 3, Figs 14–15 .

Material examined. Non-type material. Scotland [ NMW.Z], Calback Ness and Little Roe, Sullom Voe, Shetland Isles: 1997.078.0 0 62, Sta. B49, D, medium to coarse sand, 20 m, Coll. IOE (2). North Sea [ ZMH], P– 13285, AD 723, Sta. 2 (9).

Additional material. Chone duneri Malmgren, 1867 [ ZMUC POL –1755, Norway]. Chone infundibuliformis Kr ø yer, 1856 [ ZMUC POL –1749, lectotype].

Description. Colour, body shape, and size. Body cream coloured. Trunk cylindrical. Body length 3.5–10 mm, width 0.5–1.5 mm. Tubes unknown.

Branchial lobes and branchial crown. Insertion of the branchial lobes not exposed beyond collar ( Fig. 11 C). Branchial crown length: 2.5 mm. Radioles: 6 pairs. Median pinnules three times longer than more proximal pinnules. Radiolar tips triangular, medium-sized. Palmate membrane extends three quarters the length of the branchial crown. Lateral flanges broad ( Fig. 11 A). Dorsal lips rounded, without mid-rib. Ventral lips rounded, about one quarter of the dorsal lips length. Ventral radiolar appendages: one pair, about half the length of the branchial crown.

Peristomium . Anterior peristomial ring lobe exposed beyond collar, distally bilobed. Posterior peristomial ring collar: ventral, dorsal and lateral margins entire, ventral slightly higher than dorsal ( Figs 11 B–C); 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 ( Fig. 11 B). Ratio of posterior peristomial ring collar length versus chaetiger 2 length, in lateral view: 1.5:1.

Thorax. Elongate, narrowly hooded chaetae; narrowly hooded bayonet chaetae, two posterior rows with symmetrical, paleate chaetae with long mucro ( Fig. 11 F). Uncini with the main fang surmounted by three rows of equal sized teeth, occupying a half the length of the main fang ( Fig. 11 G). Narrow glandular ridge on chaetiger 2.

Abdomen. Abdominal segments: 17. Elongate, narrowly hooded chaetae ( Fig. 11 H), upper row chaetae half as long as lower row ones; uncini with the main fang surmounted by three rows of equal in size teeth, occupying one half of the main fang length, main fang not extending beyond breast, breast rectangular ( Fig. 11 D). Posterior segments: 1–2 very elongate, narrowly hooded chaetae, 25% longer than in anterior segments; uncini modified ( Fig. 11 E). Pygidium with rounded posterior margin ( Fig. 11 A).

Gametes. Oocytes in thorax and abdomen.

Methyl green staining. Only the basal half of the ventral shield of collar is coloured ( Figs 11 A–B). Body coloured uniformly ventrally ( Fig. 11 A), dorsally is not coloured ( Fig. 11 C), pygidium is not stained.

Remarks. Chone normani have broad flanges and triangular radiolar tips of medium-sized; and abdomen shorter than thorax. For comparison, C. infundibuliformis has broad flanges but radiolar tips very short and rounded; and abdomen longer than thorax. Chone normani differ of C. duneri by having flanges very broad (narrow in C. duneri ), radiolar tips medium-sized (extra long in C. duneri ), base of the branchial lobes not exposed beyond collar (exposed in C. duneri ) and posterior abdominal uncini modified (not modified in C. duneri ). Both species have the anterior peristomial ring lobe exposed beyond collar, bilobed.

Chone normani has not been recorded since their description; however, the species could be well represented in shallow waters. Probably, specimens of C. normani are mixed in samples previously identified as C. infundibuliformis , C. duneri or C. fauveli . In this study I propose to use the shape of the radiolar tip as first step to identify C. normani (the McIntosh’s figure is useful: Pl. 3, Fig. 14 ), followed by other features of the anterior and posterior peristomial ring collar and uncini.

Figures

FIGURE 11. Chone normani. (A) Body, ventro-lateral view; (B) anterior end, ventral view; (C) same, dorso-lateral view; (D) posterior abdominal uncinus; (E) paleate chaeta; (F) thoracic uncinus; (G) abdominal elongate, narrowly hooded chaeta. (A – C) Methyl green staining. (A – G) [NMW. Z 1997.078.0062].

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 14. Chone rosea. (A) Body, lateral view; (B) anterior end, ventral view; (C) same, dorsal view; (D) paleate chaeta; (E) thoracic uncinus; (F) spermatozoa; (G) radiolar tip; (H) anterior abdominal uncinus; (I) posterior abdominal uncinus. (B – C) Methyl green staining. (A – I) [ZMH P – 1502, holotype].

FIGURE 15. Chone sp. Aleutian Islands. (A) Anterior end, lateral view; (B) same, ventral view; (C) same, dorsal view; (D) spongy cushions; (E) posterior abdomen; (F) anterior abdominal uncinus; (G – H) posterior abdominal uncini; (I – K) paleate chaetae; (L) thoracic uncinus; (M) bayonet chaeta. (A – E) Methyl green staining. (A – M) [LACM – AHF, Aleutian Cruise].