Diplocirrus toyoshioae, Jimi & Fujiwara & Kajihara, 2017

Jimi, Naoto, Fujiwara, Yoshihiro & Kajihara, Hiroshi, 2017, Remarkable biodiversity of flabelligerids in Japan: seven new species of Diplocirrus (Annelida: Flabelligeridae) from Japanese waters, Zootaxa 4337 (3) : -

Diplocirrus toyoshioae sp. nov.

(New Japanese name: Toyoshio-konbou-habouki) ( Figure 7 )

Type materials. Holotype: NSMT-Pol H-645, Hibiki-nada, 62 m depth, collected by NJ, COI sequence DDBJ accession no. LC314567 . Paratypes: NSMT-Pol P-646, Hibiki-nada, 62 m depth, collected by NJ, four incomplete specimens (9–14 mm long, 1 mm wide, 20–28 chaetigers); NSMT-Pol P-647, Hibiki-nada, 62 m depth, collected by NJ, 40 incomplete specimens (2–18 mm long, 0.8–1.2 mm wide, 11–24 chaetigers).

Description. Holotype incomplete, 12 mm long, 1 mm wide (in chaetiger 10), 33 chaetigers. Body with first 10 chaetigers swollen, thereafter cylindrical ( Fig. 7A ). Tunic whitish in ethanol with sediment particles on body wall and around base of papillae ( Fig. 7B ); particles attached on whole body wall except cephalic hood. Digitate papillae abundant, longer than wide, short, in median chaetigers about 1/5 as long as notochaetae and half as long as lateral papillae in chaetal lobe, arranged in 6–8 transverse rows per segment. Cephalic hood transparent. Gonopodial lobes and gonopores absent. Posterior region tapered, anal portion lost in holotype.

Two types of branchiae present: dorsal branchiae, 1.2 mm long, thick, with two lobes on internal side, not lamellate ( Fig. 7C ); ventral branchiae, 1.3 mm long, thin, smooth, not lamellate ( Fig. 7D ). Palps 1 mm long, grooved. Upper and lateral lips well developed. Caruncle projected, not separating dorsal branchiae ( Fig. 7E ). Eyes absent. Nephridial lobe present.

Parapodia poorly developed, with chaetae emerging from body wall; notopodia with 3–4 lateral papillae arranged in single row on anterior side and no lateral papillae on posterior side; neuropodia with no lateral papillae and anterior side and 2–3 lateral papillae on posterior side. Cephalic cage developed (1 st notochaeta 1.0 mm long). Notochaetae 3–5 per bundle, multiarticulate ( Fig. 7F ) with 11–12 articles in chaetiger 34; tip tapered. Neurochaetae 4–5 per bundle, multiarticulate with 12–18 articles in chaetiger 34, rounded projection well developed ( Fig. 7G ); subdistal article 3–4 times longer than wide; tip slightly falcate.

Etymology. This species is named after the R/V Toyoshio -maru. The type specimens from Hibiki-nada were collected by the gear of R/V Toyoshio -maru. The specific name is a noun in the genitive case.

Distribution. Only known from the type locality (Hibiki-nada), 62 m depth.

Remarks. Diplocirrus toyoshioae sp. nov. resembles D. glaucus ( Malmgren, 1867) and D. tohokuensis sp. nov. in the following features: i) body papillae are short and abundant, ii) body is covered with sediment particles, iii) anterior chaetigers are swollen, and iv) gonopores are absent. These three species can be discriminated by i) cephalic cage, ii) neurochaeta, and iii) color of the anterior chaetigers. The cephalic cage in D. toyoshioae sp. nov. and D. glaucus are longer (as long as body width), whereas in D. tohokuensis sp. nov. is not well developed (1/3 as long as body width). The neurochaetal round projection is well developed in each article of D. toyoshioae sp. nov., whereas they are poorly developed in D. tohokuensis and D. glaucus . The anterior chaetigers of D. toyoshioae sp. nov. and D. tohokuensis sp. nov. are whitish, whereas these possess rusty pigments in D. glaucus .

Figures

FIGURE 7. Diplocirrus toyoshioae sp. nov. Holotype (NSMT-Pol H- 645). A, anterior end, dorsal view. B, body wall, ventral view. C, dorsal branchia. D, ventral branchia. E, prostomium. F, notochaetae, chaetiger 35. G, neurochaetae, chaetiger 35 (insert: chaetal tip). Arrow indicates rounded projections. Abbreviations: BS, branchial scar; Ca, caruncle; NL, nephridial lobe; PS, palp scar. Scale bars: A, 5 mm; B, 250 µm; C – E, 500 µm; F – G, 100 µm; G (insert), 20 µm.