Remarkable biodiversity of flabelligerids in Japan: seven new species of Diplocirrus (Annelida: Flabelligeridae) from Japanese waters Author Jimi, Naoto Author Fujiwara, Yoshihiro Author Kajihara, Hiroshi text Zootaxa 2017 2017-10-19 4337 3 journal volume 31802 10.11646/zootaxa.4337.3.2 53927ce7-a83a-4a6d-929b-b4269892bd23 1175-5326 1024922 D927258A-BF86-4E22-8725-8DD2CADAD3A0 Diplocirrus asamushiensis sp. nov. (New Japanese name: Asamushi-konbou-habouki) ( Figure 1 ) Type materials. Holotype : NSMT-Pol H-633, Asamushi, 2–5 m depth, collected by NJ, COI sequence DDBJ accession no. LC314563 . Paratypes : NSMT-Pol P-634, Asamushi, 2–5 m depth, collected by NJ, one complete specimen ( 28 mm long, 1.8 mm wide, 39 chaetigers) and two incomplete specimens ( 14–20 mm long, 1.6–1.7 mm wide, 15–27 chaetigers). Description. Holotype incomplete, 18 mm long, 1.8 mm wide (in chaetiger 10), 24 chaetigers. Body with first 13 chaetigers swollen, thereafter cylindrical ( Fig. 1A ). Tunic whitish in ethanol with sediment particles on base of papillae only ( Fig. 1B ). Digitate papillae abundant, white to brown, longer than wide, short, in median chaetigers about 3/20 as long as notochaetae and as long as lateral papillae in chaetal lobe, arranged in 10–12 transverse rows per segment. Cephalic hood transparent, with papillae near 1 st chaetiger . Gonopodial lobes not seen. Gonopores in chaetigers 3–9, pale brown ( Fig. 1B ). Posterior region tapered, anal part lost in holotype (no anal cirri in paratypes ). FIGURE 1. Diplocirrus asamushiensis sp. nov. Holotype (NSMT-Pol H-633). A, anterior end, lateral view. B, body wall, ventral view; arrow indicates gonopore. C, dorsal branchia. D, ventral branchia. E, prostomium. F, notochaetae, chaetiger 25. G, neurochaetae, chaetiger 25. Abbreviations: BS, branchial scar; Ca, caruncle; LL, lateral lip; NL, nephridial lobe; PS, palp scar. Scale bars: A, 5 mm; B, 250 µm; C–E, 500 µm; F–G, 100 µm. Two types of branchiae present: dorsal branchiae 1.5 mm long, thick, with one lobe in internal side, not lamellate ( Fig. 1C ); ventral branchiae 2 mm long, thin, smooth, not lamellate ( Fig. 1D ). Palps 3 mm long, grooved. Upper and lateral lips well developed. Caruncle projected, not separating dorsal branchiae ( Fig. 1E ). Eyes absent. Nephridial lobes present. Parapodia poorly developed, chaetae emerging from body wall; lateral papillae in chaetal lobes as long as other body papillae. Cephalic cage poorly developed (1 st notochaeta 0.2 mm in length). Notochaetae 4–7 per bundle, multiarticulate ( Fig. 1F ) with 34–37 articles in chaetiger 24; tip smooth. Neurochaetae 2–3 per bundle, multiarticulate ( Fig. 1G ) with 7–9 articles in chaetiger 24, rounded projection poorly developed; subdistal article 5–6 times longer than wide; tip falcate. Distribution. Only known from the type locality (Asamushi); 2–5 m depth. Etymology. This species is named after the type locality (Asamushi). The specific name is an adjective. Remarks. Diplocirrus asamushiensis sp. nov. resembles D. nicolaji and D . mamoi sp. nov. in the following features: i ) the body papillae are abundant and short, ii ) sediment particles are attached only on the base of papillae, iii ) the cephalic cage is poorly developed, and iv ) the number of the neurochaetal articles is less than 22 in median chaetigers. These three species are discriminated by the three features: branchial forms, caruncle length, and number of neurochaetal articles. Both of the two types of branchiae in D . asamushiensis sp. nov. and D . mamoi sp. nov. are smooth, whereas they are lamellate in D . nicolaji . The dorsal branchiae of D . asamushiensis sp. nov. are shorter than the ventral ones, whereas they are as long as ventral ones in D . mamoi sp. nov. The number of the median neurochaetal articles in D . asamushiensis sp. nov. ranges from seven to nine, whereas it is 5–6 in D . mamoi sp. nov. Subdistal article of D . asamushiensis sp. nov. is 5–6 times longer than wide, whereas it in D . mamoi sp. nov. is 8–9 times longer than wide.