Chone australiensis Hartmann-Schröder, 1979

Tovar-Hernández, María Ana, 2007, On some species of Chone Krøyer, 1856 (Polychaeta: Sabellidae) from world-wide localities, Zootaxa 1518, pp. 31-68 : 38

Chone australiensis Hartmann-Schröder, 1979

Figure 4

Chone australiensis Hartmann-Schröder, 1979: 151 , Figs 363–367.

Material examined. Type material. Australia [ ZMH P–15534, holotype], Broome, 8.9.75, Probe 5.

Description. Colour, body shape, and size. Body cream coloured. Holotype complete. Body length 4 mm, width 0.25 mm. Tube unknown.

Branchial lobes and branchial crown. Insertion of the branchial crown exposed beyond collar dorsally ( Fig. 4 B). Branchial crown length 2 mm. Five radiolar pairs. Radioles with long pinnules. Radiolar tips extremely long ( Figs 4 A–B). The palmate membrane extends a half the length of the branchial crown. Lateral flanges very narrow. Dorsal lips triangular, erect, without mid-rib. Ventral lips rounded, small.

Peristomium . Anterior peristomial ring lobe not exposed beyond collar, distally entire, triangular. Posterior peristomial ring collar: antero-dorsal margins entire ( Fig. 4 B), lateral margins folded (not incised), ventral margin sligthly higher than dorsal; entire length of mid-dorsal collar margin forms a narrow gap ( Fig. 4 B). Dorsal pockets not developed. Ventral shield of collar horseshoe-shaped, three times wider than long, swollen ( Fig. 4 A). Ratio of posterior peristomial ring collar length versus chaetiger 2 length, in lateral view: 1:1.

Thorax. Chaetigers 2 to 8: notopodia– two irregular rows of elongate, narrowly hooded chaetae ( Figs 4 C, E); one anterior row with bayonet chaetae; two posterior rows with symmetrical; paleate chaetae with a medium-sized mucro ( Fig. 4 D); neuropodia– one row of acicular uncini per torus, main fang surmounted by four rows of teeth equal in size, occupying half of the main fang length. Glandular ridge on chaetiger 2 very narrow.

Abdomen. Abdominal segments: 32. Anterior segments: two transverse rows of elongate, narrowly hooded chaetae, chaetae from the upper row half as long as chaetae in lower row; uncini with the main fang surmounted by five regular rows of teeth in frontal view, equal in size, occupying one-half the length of main fang, main fang not extending beyond breast, breast rectangular. Posterior segments: 2–3 very elongate, narrowly hooded chaetae; modified uncini with the main fang surmounted by six to seven regular vertical rows of teeth equal in size, occupying three-quarters the length of main fang, main fang not extending beyond breast, breast rectangular. Pygidium with a triangular posterior margin ( Fig. 4 A).

Gametes. Holotype inmature.

Methyl green staining. Ventral collar shield not stained ( Fig. 4 A); thorax with epidermis completely glandular, stains uniformly, dorsal and ventrally ( Figs 4 A–B); abdomen less coloured ( Fig. 4 A).

Remarks. Chone australiensis was described as having the lateral collar margin incised, as Hartmann- Schröder (1979) shows in her figure 364; however, re-examination of the holotype shows that the lateral margin of collar is entire. The drawings of Hartmann-Schröder were made with the holotype mounted in a slide, where the collar is folded, not incised.

Chone australiensis and C. normani have the anterior abdominal uncini with equal sized teeth above the main fang. In C. australiensis , the ratio of posterior peristomial ring collar length versus chaetiger 2 length is 1:1 (1.5: 1 in C. normani ); the radiolar flanges are narrow (broad in C. normani ); extra long radiolar tips (medium-sized in C. normani ); the anterior peristomial ring lobe is triangular, not exposed beyond collar (bilobed, exposed beyond collar in C. normani ) and short mucro (long in C. normani ) ( Table 2 ).

Figures

FIGURE 4. Chone australiensis. (A) Body, ventral view; (B) anterior end, dorsal view; (C, E) thoracic elongate narrowly hooded chaetae; (D) paleate chaeta. (A – B) Methyl green staining. (A – E) [ZMH P – 15534, holotype].