Polycirrus holthei, Londoño-Mesa, Mario H. & Carrera-Parra, Luis F., 2005

Londoño-Mesa, Mario H. & Carrera-Parra, Luis F., 2005, Terebellidae (Polychaeta) from the Mexican Caribbean with description of four new species, Zootaxa 1057, pp. 1-44 : 4-6

Polycirrus holthei sp. nov.

Figures 1 D–H

Material examined: Type material: Holotype, ECOSUR 0 0 54 Punta Nizuc, Cancún (21°02’11.7’’N 86°46’44.2’’W), 10 Feb. 2001, 2 m, in coralline rock. Paratypes, LACM­ AHF (2), BMNH (2), same data as holotype. Additional material: Mexican Caribbean: ECOSUR TERE­14 (5) Leward of Contoy Island (21°30’8.4’’N 86°47’45.3’’W), 1 Mar. 2001, 1– 2 m, in dead Strombus gigas conch. (1) Leward of Contoy Island (21°30’8.4’’N 86°47’45.3’’W), 28 Feb. 2001, 1 m, in coralline rock. (1) Playa Corona, Cozumel Island (20°27’45’’N 86°59’04’’W), 25 Feb. 1999, 2 m, in coralline rock.

Etymology: This species is dedicated to Torleif Holthe, for his great contributions to the knowledge of Polychaeta Terebellomorpha.

Description: Holotype complete, with 42 segments; with transparent body on preserved material, 6.5 mm long, thorax 1.8 mm long, 1.1 mm wide ( Figure 1 D). Ventral groove along the body. Segments longer and swollen on middle body. Tentacles short, arising from a swollen tentacular membrane, surrounding the mouth. Eyespots absent. Upper lip with free edge as a thin clover­like membrane; lower lip reduced but conspicuous ( Figure 1 E). Seven pairs of nephridial papillae present, well developed, from segment 4, posterior to the notopodia, the first two pairs smaller. Five ventral shields present, only visible under stain. Thorax with 12 chaetigers. Notopodia from segment 2, well­developed, long and triangular. Chaetae pinnate (cones overlapped under 100x) of two sizes ( Figure 1 F). Neuropodia from segment 5, thoracic uncini smaller than abdominal ones. Thoracic uncini MF:1:3–4:5–6 ( Figure 1 G); with an upper open subrostrum; without subrostral process, and subrostrum terminating in a projected anterior process, without filament; basis almost straight, terminating in a very short posterior process; capitium short and curved in the upper region, with three rows of teeth, one over the main fang, three to four above this, and then, two lines of numerous teeth. Abdominal uncini MF:1:1 ( Figure 1 H); subrostrum very wide, large, without subrostral and anterior processes or filament; basis almost straight, finishing into a conspicuous and long posterior process; without posterior filament; occipitium long, straight, finishing into a toothed capitium, with two teeth in one row. Pygidium with rounded and terminal anus, and nine short papillae.

Remarks: Some features above are variable between specimens. Paratypes LACM­ AHF have 9 nephridial papillae, 6 ventral shields and 10–13 thoracic chaetigers. The total number of segments in specimens complete vary from 42 to 46 segments. This variation is also shown by the additional material, deposited in ECOSUR.

Discussion: Five species of Polycirrus have been described in the Grand Caribbean region: P. purpureus Schmarda, 1861 ; P. pennulifera Verrill, 1900 ; P. eximius dubius Day, 1973 ; Polycirrus sp. A Kritzler, 1984, and Polycirrus sp. B Kritzler, 1984. Among this species, P. holthei sp. nov resembles P. pennulifera , P. eximius dubius and Polycirrus sp. B by having notopodia starting from segment 2; however, P. holthei sp. nov differs from all these species by having pinnate notochaetae, while the other species have hispid notochaetae. The segment on which notopodia in P. purpureus are first present is unknown, but this species has smooth notochaetae.

Type locality: Punta Nizuc Cancún, Quintana Roo, Mexico Distribution: Northern Mexican Caribbean

Figures

FIGURE 1. Lysilla sp. A. Ventral view; B. Chaetiger from segment 4; C. Parapodia from segment 8. Polycirrus holthei sp. nov. D. Dorsal view; E. Ventral view; F. Chaetae pinnate from segment 2; G. Thoracic uncini from segment 8 (0.02 mm); H. Abdominal uncini from segment 14. Scale bars: A, D, E, 1 mm; B 0.05 mm; C, 0.5 mm; F, G, H, 0.02 mm.