Chaetacanthus pomareae ( Kinberg, 1856 )

Salazar-Silva, Patricia, López-Sánchez, Daniel A. & Salazar-Vallejo, Sergio I., 2020, Revision of Chaetacanthus Seidler, 1922 (Annelida, Phyllodocida, Polynoidae), Zootaxa 4885 (3), pp. 395-422 : 415-417

Chaetacanthus pomareae ( Kinberg, 1856)

Figures 17 , 18

Lepidonotus pomareae Kinberg, 1856: 383 ; Kinberg 1858: 10, Pl. 3, Fig. 9 , Pl. 10, Fig. 47; Seidler 1924: 20 (key), 32–33. Chaetacanthus pomareae: Hartman 1948: 27–29 , Pl. 3, Figs 13 , 14 .

Type material. Central South Pacific, French Polynesia. Holotype of Lepidonotus pomareae Kinberg, 1856 , SMNH 395 , Tahiti, 20°S, 150° W, Freg. Eugenie Exped. 1851–53.

Diagnosis. Chaetacanthus with branchial filaments single, thick lobes; elytra with globular micropapillae and microtubercles; round macrotubercles larger on first pair of elytra; conical macrotubercles in following elytra, macrotubercles up to five times longer than wide, basally spinous, tips long, smooth; elytra without large, amber-colour macrotubercles arranged in honeycomb like groups.

Description. Holotype in poor condition, without posterior end, 1.2 cm long, 0.3 cm wide, 23 segments. Data from description and illustrations by Kinberg (1858) given in parentheses.

Prostomium bilobed, hexagonal, as long as wide; two pairs of eyes, without pigmentation; anterior pair on middle part, posterior pair near to posterior margin ( Fig. 17A ). Facial tubercle prominent, pointed. Median antenna with ceratophore long, inserted frontally, style long, expanded subdistally, tip filiform (slightly longer than laterals). Lateral antennae with ceratophores inserted terminally, styles thin, shorter than median antenna, similar in shape to median antenna ( Fig. 17A ). Palps with stout papillae, tapered, as long as median antenna. Pharynx missing (previously removed; 12 pairs of marginal papillae; jaws with smooth cutting edge).

Tentacular segment not visible dorsally; tentaculophores long, thin, with chaetae; tentacular cirri similar in shape to antennae. Segment two dorsally projected on prostomium as a nuchal rounded lobe ( Fig. 17A ).

Elytra with fringe of short papillae; surface granular with numerous microtubercles, and digitiform papillae ( Fig. 17G ). First pair of elytra with microtubercles and macrotubercles spherical or hemispherical, spinous ( Figs 17B, C ; 18A, F ), larger in elytrophoral plug area ( Fig. 18B ). Elytra of median and posterior segments oval with fringe of slender papillae ( Figs 17F ; 18C, E ), surface with numerous conical macrotubercles, amber incolour, sclerotized, basally spinous, tips long ( Figs 17D, E ; 18D, E, G, H ), larger macrotubercles over elytrophoral plug area.

Parapodia biramous, with branchial filaments laterally to eytrophores, cirrophores and between neuropodia. Notopodia shorter than neuropodia. Neuropodia with postchaetal rounded lobe, prechaetal lobe with a small acicular lobe, acicular tips slightly projected. Dorsal cirri short, thin, smooth, with subdistal swelling, tips filiform. Cirrophores short. Ventral cirri thin, short, tips filiform. Nephridial papillae from segment seven.

Notochaetae abundant, long, slender, with minute rows of spines. Neurochaetae thicker than notochaetae; upper bundle with shorter chaetae, tips with subdistal spines. Pygidium with anal cirri long, similar to dorsal cirri, anus terminal in last segment.

Remarks. The specific epithet given by Kinberg most probably refers to Queen Animata Pômare, who reigned in Tahiti from 1827 to 1877, an account of whom is given by O’Brien (2006). The type specimen is the only known record.

The holotype of C. pomareae ( Kinberg, 1856) is about half as long as the critical size indicated by Augener (1927), and herein confirmed; however, instead of having many globular macrotubercles densely packed, there are just a few, and they have very long, conical macrotubercles in the elytrophoral plug area. Consequently, we are confident about using the type, size, and density of globular macrotubercles as diagnostic features, and that C. pomareae differs from its congeners by having a low density of globular macrotubercles, and many conical macrotubercles.

Type locality. Tahiti , French Polynesia (20°S, 150° W) .

Distribution. Only known from the locus typicus.

Figures

FIGURE 9. Chaetacanthus harrisae n. sp., holotype (LACM 245). A. First elytron, dorsal view. B. Same, spiny microtubercles. C–E. Same, close up of spiny microtubercles. F. Elytron of middle segment, dorsal view. G. Globular central macrotubercles from first elytron. Scale bars: A, F: 1.1 mm; B, G: 0.1 mm; C: 0.3 mm; D, E: 0.01 mm.

FIGURE 13. A–C. Chaetacanthus ornatus n. sp., holotype (ECOSUR 233) elytra in dorsal view. D–F. C. brasiliensis, nontype specimen (ECOSUR P 3100) elytra; A, D. Elytra of first pair. B, E. Right elytra of middle segment. C, F. Right elytron of posterior segment. Scale bars: A, B: 0.6 mm; C, D: 0.7 mm; E: 1.4 mm; F: 2 mm.

FIGURE 14. Chaetacanthus pilosus (Treadwell, 1937), holotype (AMNH 3531). A. Anterior end, dorsal view. B. First elytron, dorsal view. C. Elytron from second pair, dorsal view. D. Elytron from posterior segment, dorsal view. E. Parapodium from median segment (arrow points to branchiae), anterior view. F. Parapodium from another median segment (arrow points to branchiae). Scale bars: A: 2.4 mm; B–D: 1.1 mm; E, F: 0.4 mm.

FIGURE 17. Chaetacanthus pomareae (Kinberg, 1856), holotype (SMNH 395). A. Anterior end, dorsal view. B, C. Microtubercles from first elytron. D, E. Macrotubercles, conical, from middle elytra. F. Marginal papillae or fringe. G. Digitiform micropapillae, distally globular. H. Neurochaetal tips form middle parapodium. Scale bars: A: 2 mm; B–E, H: 0.03 mm; F, G: 0.01 mm.

FIGURE 18. Chaetacanthus pomareae (Kinberg, 1856), holotype (SMNH 395). A. First elytron, dorsal view. B. Same, globular macrotubercles. C. Elytron form middle segments. D. Same, surface with conical microtubercles and macrotubercles. E. Same, marginal conical macrotubercles. F. Spiny microtubercles from first elytra. G, H. Close-up of conical macrotubercles. Scale bars: A, C: 0.1 mm; B, D, E: 0.1 mm; F, G: 0.03 mm.