Leocratides filamentosus Ehlers, 1908

Jimi, Naoto, Tanaka, Masaatsu & Kajihara, Hiroshi, 2017, Leocratides (Annelida: Hesionidae) from the Pacific Coast of Middle Honshu, Japan, with a Description of Leocratides kimuraorum sp. nov., Species Diversity 22, pp. 133-141 : 137-139

publication ID	https://doi.org/ 10.12782/sd.22_133
publication LSID	lsid:zoobank.org:pub:CD308AA8-CCA0-4831-B7CB-3052E946588F
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treatment provided by	Felipe
scientific name	Leocratides filamentosus Ehlers, 1908
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Treatment

Leocratides filamentosus Ehlers, 1908 View in CoL

[New Japanese name: hanakago-otohime-gokai] ( Figs 3 View Fig , 4 View Fig )

Leocratides filamentosus Ehlers, 1908: 63 View in CoL , pl. 6, figs 8–12; Pettibone 1970: 230–231, figs 27–28; Pleijel 1998: 112.

? Leocratides filamentosus View in CoL ; Rullier 1972: 58; Imajima 2005: 82; 2006: 351; Belal and Ghobashy 2012: 178 (as L. filamentosa [sic]).

Material examined. Nine specimens: NMST-Pol 113219, one specimen, sex unknown, Sagami Bay , St . 1, 213–255 m depth, 29 June 2011, collected by MT (right parapodium of chaetiger 10 removed for observation; preserved in 70% ethanol in a 2.0 ml plastic tube, kept in the same vial together with the rest of the body); NSMT-Pol 113220, eight specimens, one female and others of unknown sex, Sagami Bay , St . 3, 292–375 m depth, 15 February 2017, collected by NJ, MT, HK .

Sequence. LC258083 View Materials , COI gene, 592 bp, determined from a specimen of NSMT-Pol 113220.

Description. 14–30 mm long, 2–4 mm wide in chaetiger 7 (not including parapodia), 21 segments, 16 chaetigers; right parapodium of chaetiger 10 removed for observation. Body cylindrical, tapered in posterior region, transparent in live ( Fig. 3A, B View Fig ), whitish in ethanol; dorsal integument annulated, with 12–17 transverse wrinkles per segment. Brown lines on dorsal surface absent ( Fig. 3A, C View Fig ); ventrally with black spots of varying size and shape arranged along median groove, in some places roughly on two rows, in chaetigers 5–16; some spots being particularly larger than others, arranged laterally in pair along line between parapodia in each segment, especially prominent in chaetigers 7–11 ( Fig. 3B View Fig ). Prostomium rectangular, longer than wide, mid-dorsally with shallow depression, square in shape from dorsal view ( Fig. 3D View Fig ). Median antenna conical, smooth, in central part of prostomium, not reaching anterior prostomial margin, 1.3 times longer than lateral antennae. Lateral antennae conical, smooth, on anterior edge of prostomium. Palps bi-articulated, 1.2 times longer than lateral antennae, palpophore four times longer than palpostyle, ventral to antennae ( Fig. 3D View Fig ). Eyes brownish, two pairs, on mid-lateral part of prostomium, anterior pair slightly larger and more separated than posterior one ( Fig. 3D View Fig ). Facial tubercle present mid-ventrally on prostomium; papillose peristomial membrane present ( Fig. 3E View Fig ).

Tentacular cirri eight pairs, long, thick; longest one reaching chaetiger 6. Lateral cushions low, barely projected dorsally, slightly projected laterally, undivided, with 7–8 longitudinal wrinkles per one lateral cushion ( Fig. 3C View Fig ).

Parapodia uniform throughout; chaetal lobes cylindrical, truncate, as long as wide ( Fig. 4A View Fig ); dorsal cirri with cirrophores cylindrical, smooth, 1.3 times longer than wide ( Fig. 4B View Fig ); cirrostyle whip-like, smooth, annulated, longer than body width (without parapodia). Ventral cirri basally rugose, surpassing chaetal lobe, reaching up to half length of neurochaetal bundle ( Fig. 4C View Fig ).

Neuropodial acicula black, tapered; acicular lobe single, wider basally, tip digitate, long ( Fig. 4D View Fig ). Neurochaetae about 20 per bundle ( Fig. 4E View Fig ); handle greenish; blade yellowish, bidentate, six times longer than wide; with subdistal tooth 0.5 times longer than apical tooth; guard absent ( Fig. 4F View Fig ).

Cirri of prepygidial segment broken; pygidium smooth, depressed, with paired cirri; anus dorso-terminal, with about eight anal papillae.

Pharynx dissected, about 20 terminal low cushion-like terminal papillae present ( Fig. 3F View Fig ); dorsal jaw two plates, ventral jaw one plates.

Confirmed distribution. From Sagami Bay, Japan to Indonesia, 213–677 m depth, in hexactinellid sponges.

Remarks. Imajima (2003, 2007) reported “ Leocratides filamentosus ” from Japanese waters. However, as indicated above Imajima’s (2003, 2007) specimens from Sagami and Suruga Bays actually belong to L. kimuraorum sp. nov. Imajima (2005, 2006) also reported “ L. filamentosus ” from off Izu-Oshima Island, Sagami Bay, and several other localities off the Nansei Islands, southwestern Japan, but neither morphological accounts nor the basis of his identifications were provided. We searched unregistered polychaete collection in NSMT for the voucher specimens that substantiate Imajima’s (2005, 2006) records of his “ L. filamentosus ” from Izu-Oshima Island, Sagami Bay, and the Nansei Islands, but were not able to locate them. This makes the validity of these records of “ L. filamentosus ” rather obscure. Thus, we conclude that there has been no reliable distributional records of L. filamentosus from Japanese waters and this study represents the first record of the species for Japan.

Out of the type locality and Japanese waters, Rullier (1972) and Belal and Ghobashy (2012) also reported “ Leocratides filamentosus ” from extremely shallow depths (up to 8 m depth) in New Caledonia and Lake Timsah of the Suez Canal, Egypt, respectively. However, these studies provided only a brief account or an inadequate illustration and we consider these records are doubtful.