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 ohtsukai sp. nov. (New Japanese name: Ohtsuka-konbou-habouki) ( Figure 4 ) Type materials. Holotype : NSMT-Pol H-638, Hibiki-nada, 62 m depth, collected by NJ, COI sequence DDBJ accession no. LC314565 . Paratypes : NSMT-Pol P-639, Hibiki-nada, 62 m depth, six incomplete specimens ( 5–24 mm long, 1.5–2.0 mm wide, 10–21 chaetigers). Description. Holotype incomplete, 16 mm long, 3 mm wide (in chaetiger 10), 19 chaetigers. Body with first 13 chaetigers swollen, cylindrical ( Fig. 4A ). Tunic whitish in ethanol with fine sediment particles on body wall and papillae ( Fig. 4B ); particles present on whole body wall except cephalic hood. Digitate papillae in whole body abundant, longer than wide, short, in median chaetigers about 1/25 as long as notochaetae and half as long as lateral papillae in chaetal lobe, arranged in 14–15 transverse rows per segment. Cephalic hood transparent, with papillae near 1 st chaetiger . Gonopodial lobes not seen. Gonopores present in chaetigers 3–12, white ( Fig. 4B ). Posterior region tapered; anal part lost in holotype . FIGURE 3. Diplocirrus mamoi sp. nov. Holotype (NSMT-Pol H-636). A, anterior end, lateral view. B, body wall, ventral view; arrow indicates gonopore. C, dorsal branchia. D, ventral branchia. E, prostomium. F, notochaetae, chaetiger 29. G, neurochaetae, chaetiger 29. Abbreviations: BS, branchial scar; Ca, caruncle; LL, lateral lip; NL, nephridial lobe; PS, palp scar. Scale bars: A, 5 mm; B–E, 500 µm; F, 50 µm; G, 100 µm. FIGURE 4. Diplocirrus ohtsukai sp. nov. , Holotype (NSMT-Pol H-638). A, whole body, ventrolateral view. B, body wall, ventral view; arrow indicates gonopore. C, dorsal branchia. D, ventral branchia. E, prostomium. F, notochaetae, chaetiger 20. G, neurochaetae, chaetiger 20 (insert: chaetal tip). Abbreviations: BS, branchial scar; Ca, caruncle; LL, lateral lip; NL, nephridial lobe; PS, palp scar. Scale bars: A, 5 mm; B–E, 500 µm; F–G, 100 µm. Two types of branchiae present: dorsal branchiae 3 mm long, thick, with single lobe in internal side, not lamellate ( Fig. 4C ); ventral branchiae 7 mm long, thin, smooth, not lamellate ( Fig. 4D ). Palps 8 mm long, grooved. Upper and lateral lips well developed. Caruncle projected, not separating dorsal branchiae ( Fig. 4E ). Eyes absent. Nephridial lobes present. Parapodia poorly developed, chaetae emerging from body wall; notopodia with 3–5 lateral papillae on anterior side and no lateral papillae on posterior side; neuropodia with 5–7 lateral papillae on anterior side and 2 lateral papillae on posterior side. Cephalic cage developed (1 st notochaeta 2.0 mm in length). Notochaetae 7–9 per bundle, multiarticulate ( Fig. 4F ) with 51–59 articles in chaetiger 20; tip tapered. Neurochaetae 4–5 per bundle, multiarticulate ( Fig. 4G ) with 8–13 articles in chaetiger 20, rounded projection poorly developed; subdistal article 3–4 times longer than wide; tip slightly falcate. Distribution. Only known from type locality (Hibiki-nada, 62 m depth). Etymology. This species is named after Prof. Susumu Ohtsuka who organized the research cruise of the R/V Toyoshio -maru at the type locality, Hibiki-nada. The specific name is a noun in the genitive case. Remarks. Diplocirrus ohtsukai sp. nov. resembles D. salazarvallejoi Teixeira, Rizzo & Santos, 2015 (originally described from Brazil ) in the following features: i ) body papillae are short and abundant, ii ) body is covered with sand particles, iii ) lateral papillae are short, iv ) anterior chaetigers are swollen, and v ) gonopores are present. The two species can be discriminated by i ) size of the cephalic cage and ii ) position of the swollen area in the body. The cephalic cage of D . ohtsukai sp. nov. is well developed (2/3 of body width), whereas that of D . salazarvallejoi is not (1/4 of body width). The swollen area in D . ohtsukai sp. nov. is along first 12–13 chaetigers, whereas it is along 8 chaetigers in D . salazarvallejoi .