Capitellidae, Grube, 1862

Silva, Camila Fernanda Da & Amaral, Antonia Cecilia Zacagnini, 2022, Capitellidae (Annelida) from the Brazilian Continental Margin (SW Atlantic): new occurrences of three genera and description of new species, Zootaxa 5104 (1), pp. 89-110 : 92

Key to species of Capitellidae examined in this study

1. Thorax with 11 chaetigers.............................................................................. 2

2a. Abdominal chaetigers with hooded hooks only.............................................................. 3

2b. Abdominal chaetigers with capillaries in a variable arrangement................................................ 4

3. (2a) Eyespots absent; proboscis with very coarse papillae; chaetigers 1–3 with only capillaries, remaining thoracic chaetigers with modified spatulate chaetae ( Fig. 1A ); peristomium and chaetigers 1–2 slightly tessellated laterally, with shallow lateral groove; branchiae absent............................................... Peresiella megapapilata sp. nov. ( Figs 1B , 4A–H )

4a. (2b) Thorax with capillaries except on neuropodia of chaetiger 11, with hooded hooks; chaetigers 2–7 with a deep lateral groove; all chaetigers biannulate, with shallow intersegmental division; chaetigers 9–11 with mid-lateral lobes; notopodia of first nine abdominal chaetigers with mixed hooded hooks and capillaries; retractile dorsal branchiae, digitiform (up to seven filaments), anterior to notopodial lobe..................................................... Mastobranchus loii ( Fig. 2A–F )

4b. (2b) Prostomium triangular, small; thorax with capillaries only; chaetigers 1–4 wide and inflated, with a shallow lateral groove; chaetigers 5–11 square-like, strongly biannulated, with deep intra- and intersegmental grooves; genital pores between chaetigers 7/8, 8/9, 9/10, 10/11, and 11/12; abdominal chaetigers with hooded hooks on neuropodia and mixed hooded hooks and capillaries on notopodia; dorsal, bifurcated branchiae, posterior to notopodial lobe..................................................................................................... Mastobranchus braziliensis sp. nov. ( Figs 1C , 3A–J )

4c. (2b) Prostomium conical; chaetiger 1 uniramous; thorax with capillaries except on neuropodia of chaetiger 11, with hooded hooks; peristomium and chaetigers 1–3 strongly tessellated; deep lateral groove on peristomium and chaetigers 1–4; genital pores between chaetigers 7/8, 8/9, 9/10, 10/11, 11/12, and 12/13; abdomen with capillaries on notopodia up to chaetiger 24 and hooded hooks on all neuropodia; branchiae and pygidium unknown....... Polymastigos profundus sp. nov. ( Figs 1D , 5A–I )

Figures

FIGURE 1. Morphology of the studied genera. (A) Modified spatulate chaetae of Peresiella megapapilata sp. nov., lateral view; (B) Peresiella megapapilata sp. nov., lateral view; (C) Mastobranchus braziliensis sp. nov., lateral view; (D) Polymastigos profundus sp. nov., dorsal view on thorax and lateral view on abdomen. A: abdomen. Ch: chaetiger. NeL: neuropodial lobe. Pe: peristomium. Pr: prostomium. T: thorax. Scale bars: A, 10 µm; B, C, D, 1.0 mm.

FIGURE 2. Mastobranchus loii (A) Anterior region, lateral view; (B) Thoracic region, dorsal view; (C) Thorax-Abdomen division, dorsal view; (D) Thorax-Abdomen division, lateral view; (E) Abdominal region, dorsal view; (F) Posterior end. A: abdomen. Br: branchiae. Ch: chaetiger. MLL: mid-lateral lobe. NeL: neuropodial lobe. NoL: notopodial lobe. Pe: peristomium. Pr: prostomium. T: thorax. Scale bars: A, B, C, D, E, F, 0.5 mm.

FIGURE 3. Mastobranchus braziliensis sp. nov. (A) Anterior region, lateral view; (B) Thoracic region, lateral view; (C) Abdominal region, dorsal view; (D) Abdominal region, ventral view; (E) Posterior end; (F) Methyl Green staining pattern; (G) Notopodial hooded hooks, lateral view; (H) Notopodial hooded hooks, frontal view; (I) Neuropodial hooded hooks, lateral view; (J) Neuropodial hooded hooks, frontal view. A: abdomen. Br: branchiae. Ch: chaetiger. MLL: mid-lateral lobe. NeL: neuropodial lobe. NoL: notopodial lobe. Pa: palpode. Pe: peristomium. Pr: prostomium. T: thorax. Black arrows: genital pores. Scale bars: A, E, 0.2 mm; B, C, D, F, 0.5 mm; G, H, I, J, 5 µm.

FIGURE 4. Peresiella megapapilata sp. nov. (A) Anterior region, lateral view; (B) Thoracic region, lateral view; (C) Anterior region, dorsal view; (D) Methyl Green staining pattern; (E) Modified spatulate chaetae; (F) (G) Notopodial hooded hook, frontal view; (H) Neuropodial hooded hook, top view. A: abdomen. Ch: chaetiger. NeL: neuropodial lobe. NoL: notopodial lobe. Pa: palpode. Pb: proboscis. Pe: peristomium. Pr: prostomium. SpCh: spatulate chaetae. T: thorax. Scale bars: A, 0.2 mm; 1 mm; B, D, 0.5 mm; C, 0,1 mm; E, 10 µm; F, G, 2 µm; H, 5 µm.

FIGURE 5. Polymastigos profundus sp. nov. (A) Thoracic region, lateral view; (B) Anterior end, lateral view; (C) Abdominal region; lateral view; (D) Abdominal region; dorsal view; (E) Abdominal region; ventral view; (F) Methyl Green staining pattern, lateral view; (G) Methyl Green staining pattern, ventral view; (H) Notopodial hooded hook, frontal view; (I) Neuropodial hooded hook, frontal view. A: abdomen. Ch: chaetiger. GP: genital pores. LG: lateral groove. NeL: neuropodial lobe. NoL: notopodial lobe. Pa: palpode. Pb: proboscis. Pe: peristomium. Pr: prostomium. T: thorax. White arrows: genital pores. Scale bars: A, F, 1 mm; B, E, 0.2 mm; C, D, G, 0.5 mm; H, I, 5 µm.