Leocratides jimii, Salazar-Vallejo, 2020

Salazar-Vallejo, Sergio I., 2020, Revision of Leocrates Kinberg, 1866 and Leocratides Ehlers, 1908 (Annelida, Errantia, Hesionidae), Zootaxa 4739 (1), pp. 1-114 : 79-80

Leocratides jimii n. sp.

Fig. 45

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Type material. Madagascar. Holotype ( MNHN A861 ), 50 km NW off Nosy Mitsio, R / V Vauban, Sta. 9:44 (12°39’05” S, 48°15’06” E), 450 m, 1 Aug. 1973, A. Crosnier, coll.

Description. Holotype (MNHN A861), complete, bent ventrally. Body obconic, blunt, wider anteriorly, tapered posteriorly, 34 mm long, 6 mm wide, 16 chaetigers; right parapodium of chaetiger 8 removed for observing parapodial features (kept in container), right parapodium of chaetiger 5 in regeneration. Tentacular and dorsal cirri without tips, or broken. Integument pale, slightly darker along anterior region ( Fig. 45A ); venter with a wide, dark brown longitudinal band, from chaetiger 5 to end of body ( Fig. 45B ), darker along chaetigers 6–9.

Prostomium as long as wide, slightly wider anteriorly, lateral margins slightly constricted before anterior eyes ( Fig. 45C ). Lateral antennae with ceratophores distinct, as long as prostomium, as long as palps; palpophores twice longer than palpostyles; median antenna about twice longer and wider than lateral ones, inserted centrally among eyes.

Eyes dark brown, round, anterior eyes slightly larger and more distant to each other than posterior ones; in lateral view anterior and posterior eyes close to each other ( Fig. 45D ).

Nuchal organs partially covered by tentacular belt. Lateral lobes oval, markedly separated middorsally, divergent; lateral ciliated bands wide, visible dorsally. Lateral cushions low, bipartite along body; longitudinal striae better defined along anterior third of body.

Peristomial dorsolateral tubercles as wide as prostomium, each with four thick, digitate lobes, each about twice longer than wide. Ventral ridge with 8 thick, digitate, as long as wide papillae, midventral ones slightly smaller.

Pharynx exposed ( Fig. 45D, E ). Upper jaw double, low, crescent shaped, lower jaw single, tapered. Anterior margin with about 20 low papillae. Lateral vesicles not seen.

Dorsal cirri broken, as long as body width ( Fig. 45F ). Neuracicular lobes globose, as long as wide, or slightly longer than wide ( Fig. 45F , inset). Neurochaetae about 40 per bundle, blades slightly decreasing in size ventrally ( Fig. 45G ), 3–4 times longer than wide, bidentate, without guards ( Fig. 45H ).

Posterior region tapered. Prepygidial segment with dorsal cirri without tips, about 5 times longer than ventral ones. Pygidium distorted, anus terminal, one cirri missing, the other broken.

Oocytes not seen.

Etymology. This species is being named after Naoto Jimi, from the National Institute of Polar Research, Tokyo, a young productive polychaete taxonomist and kind colleague, in recognition of his publications on polychaete taxonomy, and especially because he participated in the description of the most recent Leocratides species. The species-group name is a noun in the genitive case ( ICZN 1999, Art. 31.1.2).

Remarks. As indicated in the key above, Leocratides jimii n. sp. resembles L. filamentosus Ehlers, 1908 by having peristomial dorsolateral tubercles with thick digitate lobes. They differ by their ventral pigmentation pattern and development of neuracicular lobes. In L. jimii there is a wide brownish band, better defined medially, and neuracicular lobes are as long as wide, globose, whereas in L. filamentosus there is no ventral pigmentation, and neuracicular lobes are longer than wide, tapered into small mucros.

Distribution. Off Nosy Mitsio, Madagascar, 450 m depth.

Figures

FIGURE 45. Leocratides jimii n. sp., holotype (MNHN A861). A. Anterior region, dorsal view. B. Anterior region, ventral view. C.Anterior end, dorsal view, MGS. D. Same, lateral view (*: lateral papilla). E. Pharynx, frontal view. F. Chaetiger 8, right parapodium, anterior view (inset: neuracicular lobe). G. Same, neurochaetae. H. Neurochaetal blades, lateral view. Scale bars: A, B: 1.4 mm; C, E: 1.1 mm; D: 0.9 mm; F: 0.8 mm; G: 0.1 mm; H: 35 µm.