Chone paracincta Hartmann-Schroder 1962

Chone paracincta Hartmann-Schröder, 1962

Figure 13

Chone paracincta Hartmann-Schröder, 1962: 145 –146, Pl. 19, Figs 125–126, Pl. 20, Fig. 126.

Material examined. Type material. Callao [ZMH P–15209, syntype], Peru, Coll. Noodt, 29.5.56.

Additional material. Chone acustica (Claparède, 1870) [MNCN, neotype]. Chone albocincta Banse, 1972 [LACM – AHF POLY 0 455, paratypes]. Chone gambiae Tovar-Hernández et al. (2007) [MNCN 16.01/7366, holotype]. Chone perkinsi Tovar-Hernández, 2005 [ECOSUR 0 0 53, paratype].

Description. Colour, body shape, and size. Syntype complete. Body cream-coloured. Trunk cylindrical. Body length 11 mm, width 2 mm. Tubes unknown.

Branchial lobes and branchial crown. Insertion of the branchial crown exposed beyond collar (Fig. 13 B). Branchial crown length 2 mm. Radioles: 6 pairs. Median pinnules longer than more proximal pinnules. Radiolar tips short (Fig. 13 A). Palmate membrane extends about three quarters the length of the branchial crown. Lateral flanges broad. Dorsal lips elongate. Ventral lips rounded, small. Ventral radiolar appendages: one pair, about one quarter the length of the branchial crown.

Peristomium. Anterior peristomial ring lobe not exposed beyond collar, distally entire, triangular. Posterior peristomial ring collar: antero-dorsal (Fig. 13 B), ventral (Fig. 13 C) and lateral margins (Fig. 13 A) entire, ventral margin slightly higher than dorsal (Fig. 13 A); the entire length of mid-dorsal collar margins forms a narrow gap (Fig. 13 B). Dorsal pockets well developed. Ventral shield of collar horseshoe-shaped, swollen. Ratio of posterior peristomial ring collar length versus chaetiger 2 length, in lateral view: 2:1.

Thorax. Chaetigers 2 to 8: Notopodia: superior group with two irregular rows of elongate narrowly hooded chaetae; inferior group with one anterior row of bayonet chaetae; two posterior rows with paleate chaetae with short mucro. Neuropodia: acicular uncini distributed as a regular row, second tooth enlarged, located offset the midline, dentition covering three quarters the length of the main fang. Glandular ridge on chaetiger 2 broad laterally.

Abdomen. Abdominal segments: 26. Anterior segments: two transverse rows of elongate, narrowly hooded chaetae, upper row chaetae half as long as lower row ones; uncini with second tooth enlarged, occupying a half of the main fang length, main fang not extending beyond breast. Posterior segments: very elongate, narrowly hooded chaetae, 25% longer than those of anterior segments; uncini modified. Pygidium with rounded posterior margin (Fig. 13 D).

Gametes. Syntype inmature.

Methyl green staining. Body stains uniformly laterally (Fig. 13 A) and ventrally (Fig. 13 C), dorsally only the collar segment is coloured (Fig. 13 B).

Remarks. Chone paracincta has the following distinguisable features: glandular ridge in chaetiger 2 broad laterally, branchial lobes exposed beyond collar dorsally, and dorsal pockets well developed. Other species with glandular ridge broad laterally is C. gambiae; however, it has long radiolar tips (short in C. paracincta); anterior peristomial ring lobe exposed, bilobed (not exposed, triangular in C. paracincta) and glandular ridge on segment 9 (absent in C. paracincta). In C. acustica and C. perkinsi the glandular ridge is broad dorsally, and in C. albocincta the ridge is broad ventrally. Among species of Chone included in this revision, C. paracincta is unique by having a glandular ridge on chaetiger 2 broad laterally (Table 2).