Flabelligera kajiharai 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 : 104

Flabelligera kajiharai Jimi , sp. nov.

[Japanese name: Kajihara-kanten-habouki] ( Fig. 4 )

Material examined. Holotype (NSMT-Pol H-871): 18 mm long, 3 mm wide, 32 chaetigers, complete body, Oshoro , Hokkaido, Japan (43°12′24″N, 140°51′43″E), 5 m depth, 23 May 2017, collected by Naoto Jimi. Paratypes: 1 specimen (NSMT-Pol P-872), 20 mm long, 3 mm wide, 34 chaetigers, complete body, collected with the holotype; 1 specimen (NSMT-Pol P-873), 22 mm long, 4 mm wide, 34 chaetigers, complete body, Shakotan, Hokkaido (43°14′20″N, 140°43′53″E), 5 m depth, collected by Naoto Jimi; 1 specimen (NSMT-Pol P-874), 21 mm long, 3 mm wide, 33 chaetigers, complete body, Samani , Hokkaido (42°7′4″N, 142°55′28″E), 1 m depth, 29 April 2019, collected by Yuki Oya .

Description. Body tapered posteriorly ( Fig. 4A ). Tunic thick, opaque, densely papillated, with cover of fine sediment particles. Sediment particles cover all of notochaetal and half of neurochaetal lobes. Body papillae long, thin, club shaped. Gonopodial lobes not seen.

Cephalic cage chaetae about 1/10 body length, as long as body width (4B). Chaetiger 1 comprising cephalic cage; chaetiger 1 with 29 notochaetae and 26 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. 4C ). Caruncle developed, wide, exceeding branchial plate margin, distally truncate ( Fig. 4C ). Lateral lips developed, fused to dorsal lip ( Fig. 4C ). Ventral lip triangular, without ventral projection. Palps pale, thick, slightly longer than branchiae, about four times thicker than branchiae. Palp scars rounded, elevated ( Fig. 4C ). Branchiae in two lateral groups, each with filaments in concentric rows, each group with 30 filaments. Nephridial lobes paired, basal to caruncle, at median of branchial groups.

Parapodia developed, lateral; median neuropodia ventrolateral. Notopodial lobes projected, club shaped, exceeding half of notochaetae, without different papillae. Neuropodial lobes projected, club shaped, without different papillae. Noto- and neuropodia widely separated. Notochaetae multiarticulated capillaries, transparent, 1/2 body width, 3–4 per bundle, with approximately 120 articles; articles short throughout chaetae ( Fig. 4D–F ). Neurochaetae multiarticulated capillaries in chaetiger 1. Multiarticulate neurohooks present in chaetiger 2 and succeeding posterior chaetigers, golden, one per ramus, with 6–7 medium sized articles medially, other articles anchylosed, articles absent basally. Crest slightly wider than handle, width: length ratio 1: 6 ( Fig. 4G–I ).

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

Etymology. The species is named after Dr. Hiroshi Kajihara to express the first author’s feelings of gratitude because of his leadership and high-quality advice during the graduate studies.

Remarks. This species resembles F. bophortica and F. japonica sp. nov. in having body without transverse bands, opaque tunic with fine sediments, one articulated neurohook per parapodia from chaetiger 2, long and golden crest of neurohook (Annenkova-Chropina 1924; Salazar-Vallejo 2012). Flabelligera kajiharai sp. nov. can be distinguished by having short articles of notochaetae throughout chaetae, while the other two species have medium-sized articles in notochaetae.

Figures

Fig. 4. Flabelligera kajiharai sp. nov., holotype (NSMT-Pol H-871). A, Whole body, lateral view; B, anterior end, ventral view; C, prostomium, frontal view; D, notochaetae, chaetiger 12; E, basal part of notochaetae; F, enlarged view of basal part of notochaetae; G, neurohook, chaetiger 12; H, basal part of neurohook. Scale bars: A, B, 5mm; C, 1mm; D, 200µm; E, 100µm; F, 50µm; G–I, 200µm. Abbreviations: bp, branchial plate; ca, caruncle; cc, cephalic cage; dL, dorsal lip; e, eye; ll, lateral lip; ps, palp scar.