Flabelligera kaimeiae Jimi, 2022

Jimi, Naoto, Hasegawa, Naohiro, Taru, Masanori, Oya, Yuki, Kohtsuka, Hisanori, Tsuchida, Shinji, Fujiwara, Yoshihiro & Woo, Sau Pinn, 2022, Five New Species of Flabelligera (Flabelligeridae: Annelida) from Japan, Species Diversity 27 (1), pp. 101-111 : 102-104

Flabelligera kaimeiae Jimi , sp. nov.

[Japanese name: Kaimei-kanten-habouki] ( Fig. 3 )

Material examined. Holotype (NSMT-Pol H-870):

24 mm long, 3 mm wide, 35 chaetigers, complete body, off

Ofunato , Iwate, Japan (39°06′54″N, 142°06′25″E), 265 m depth, 16 July 2019, collected by Naoto Jimi using ROV Crambon during the cruise of KM19-05 C .

Description. Body tapered posteriorly ( Fig. 3A ). Tunic thick, transparent, densely papillated, with cover of sediment particles. Sediment particles not covering notochaetal and neurochaetal lobes. Body papillae long, thin, digitate. Gonopodial lobes not seen.

Cephalic cage chaetae about 1/6 body length, as long as body width ( Fig. 3B ). Chaetiger 1 comprising cephalic cage; chaetiger 1 with 20 notochaetae and 12 neurochaetae per side. Chaetiger 1 longer than chaetigers 2–3. Chaetal transition from cephalic cage to body chaetae abrupt, chaetiger 2 with multiarticulated neurohooks.

Prostomium rounded. Brown eyes present, two pairs, anterior eyes larger than posterior ones ( Fig. 3C ). Caruncle developed, wide, exceeding branchial plate margin, distally truncate ( Fig. 3C ). Lateral lips well developed, fused to dorsal lip ( Fig. 3C ). Ventral lip triangular, without ventral projection. Palps lost ( Fig. 3C ). Palp scars rounded, elevated. Branchiae in two lateral groups, each with filaments in concentric rows, each group with 26 filaments. Nephridial lobes paired, lateral to caruncle, at median distance of branchial groups.

Parapodia developed, lateral; median neuropodia ventrolateral. Notopodial lobes projected, digitate, truncate, without different papillae. Neuropodial lobes projected, digitate, extended along half of neurochaetae, without different papillae. Noto- and neuropodia widely separated. Notochaetae multiarticulated capillaries transparent, 1/2 body width, 4–5 per bundle, with approximately 35 articles, articles mediumsized medially and distally, shorter basally ( Fig. 3D–F ). Neurochaetae multiarticulated capillaries in chaetiger 1. Multiarticulate neurohooks present in chaetiger 2 and succeeding posterior chaetigers, golden, one per ramus, three medium sized articles medially, other articles anchylosed, articles absent in basal region. Crest slightly wider than handle, width: length ratio 1: 10 ( Fig. 3G–I ).

Posterior end truncated; pygidium with anus terminal, not covered by tunic, thick muscular ring, without anal cirri.

Etymology. The specific name kaimeiae derives from R/V Kaimei, that was used for sampling of the new species.

Remarks. This species resembles F. buski ( McIntosh, 1869) in having articulated neurohooks with long crests ( McIntosh 1869; Salazar-Vallejo 2012). The new species can be discriminated by having one neurohook, while F. buski has two neurohooks per parapodium.

Figures

Fig. 3. Flabelligera kaimeiae sp. nov., holotype (NSMT-Pol H-870). A, Whole body, lateral view; B, anterior end, dorsal view; C, prostomium, frontal view; D, notochaetae, chaetiger 12; E, distal part of notochaetae; F, basal part of notochaetae; G, neurohook, chaetiger 12; H, middle part of neurohook; I, enlarged view of middle part of neurochaetae. Scale bars: A, B, 1mm; C, 0.5mm; D, 200µm; E, F, 100µm; G, 200µm; H, I, 100µm. Abbreviations: bp, branchial plate; ca, caruncle; cc, cephalic cage; dL, dorsal lip; e, eye; ll, lateral lip; ps, palp scar.