Thelepus

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 : 10

Thelepus sp.

Figures 3 A–E

Material examined: Mexican Caribbean: ECOSUR TERE­28 (1) Chinchorro Bank (18°35’51.0’’N 87°20’20.5’’W), 3 Oct. 1983. (1) Cozumel Island (20°23’45.1’’N 86°51’53.5’’W), 5 Jun. 1995. Central­America: UMML (1) R/V “Pillsbury” cruise 6802, sta. P613, Gulf of Honduras (15°58’N 88°20’W), 19 Mar. 1967, 39 m.

Description: Specimen incomplete, with 40 segments, 25.5 mm long; thorax 4 mm wide. Thorax dorsally swollen after segment 6, with midventral grooved from segment 15 until the end of the fragment. Tentacles missing. Tentacular membrane with very small dark eyespots, arranged in two rows, more concentrated laterally. Upper lip with short rounded free edge. Lower lip, thin and projecting outward ( Figures 2 A–B). Lateral lappets absent. Three pairs of branchiae, starting from segment 2, filaments digitate, spiralled ( Figure 2 B). First pair with 3 filaments, second with 4, third with 5–6 filaments. Nephridial papillae not evident. Glandular tissue surrounding notopodia 4–6; with 15 ventral shields, rectangular, short, tapering from segment 17, with a deep midventral groove. Thorax with 34 notopodia, starting from segment 3. Notochaetae bilimbate, of two sizes ( Figures 2 C); long chaetae straight, with equal­sized limbs, short chaetae curved, with asymmetric limbs. Neuropodia from segment 5, become shorter posteriorly; from segment 27, reduced to a swollen lobe with short row of uncini. Thoracic and abdominal uncini with dental formula MF:2:3 ( Figures 2 D–E); subrostrum long, deep, without subrostral process; anterior process projected forward, as a button; with long and curved basis; without posterior process; occipitium starting from a shallow depression; capitium with first row with two teeth above main fang, and second row with three teeth, the central larger than lateral teeth.

Remarks: These specimens differ from T. haitiensis and T. setosus in the number of branchial filaments, number of ventral shields and number of notopodia, being considerably higher in those species. Furthermore, the uncinal formula is different to T. haitiensis (MF:2) and similar to T. setosus (MF:2–3:2). These specimens represent an undescribed species, but the condition of the material precludes its description.

Distribution: Mexican Caribbean and Gulf of Honduras.

Figures

FIGURE 2. Streblosoma hartmanae: A. Dorsal view; B. Ventral view; C. Lateral view; D. Chaetae from segment 11; E. Uncini in lateral view from segment 11; F. Uncini in front view from segment 11. Thelepus haitiensis: G. Lateral view; H. Ventral view; I. Chaetiger from segment 10; J. Chaetae from segment 10; K. Uncini from segment 10. Scale bars: A, B, C, 0.5 mm; D, 0.03 mm; E, F, 0.02 mm; J, K 0.05; G, H 2 mm; I 0.2 mm.

FIGURE 3. Thelepus sp. A. Ventral view; B. Lateral view; C. Chaetae from segment 22; D. Uncini in lateral view from segment 7; E. Uncini in front view from segment 7. Amphitritides bruneocomata: F. Lateral view; G. Ventral view; H. Nephridial tubes from segment 11 – 13; I. Chaetae from segment 13; J. Uncini from segment 13. Scale bars: A, B, F, G 2 mm; D, E 0.2 mm; C, I, J 0.05 mm; H 0.5 mm.