Leocratides filamentosus Ehlers 1908
Creators: name: Salazar-Vallejo, Sergio I.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Phyllodocida
Hesionidae
Leocratides
Leocratides filamentosus

description: Leocratides filamentosus Ehlers, 1908
Figs 43, 44
Leocratides filamentosus Ehlers, 1908: 63–64, Pl. 6, Figs 8–12; Augener 1926: 452; Imajima & Hartman 1964: 82–83; Pettibone 1970: 230–232, Figs 27–29 [partim, figure 29 is L. ehlersi (Horst, 1921)]; Kirkegaard 1995: 30–31; Jimi et al. 2017: 137–139, Figs 3–4.
Type material. Malaysia, Western Sumatra. Six syntypes in two lots, five in one lot (ZMB 4431), and another syntype (ZMH PE-318b), Nias South Canal, R/V Valdivia, Sta. 198 (00°16’ N, 98°07’ E), 677 m, in hexactinellid sponge, Aphrocallistes bocagei Wright, 1870 (actually A. beatrix Gray, 1858) [ZMB syntypes slightly dehydrated in two containers. Larger container with four syntypes, including one with an anterior midventral dissection. Body pale, 20–36 mm long, 5–8 mm wide, 16 chaetigers. Lateral antennae as long as prostomium, as long as or slightly longer than palps; palpophores 2–3 times longer than palpostyles; median antennae missing in all these syntypes (still on site when Pettibone examined the specimens), insertion scar visible between posterior eyes. See variation for other features). Smaller container with a large specimen, 44 mm long, 4.5 mm wide, 16 chaetigers. Segments short along chaetigers 1–5, less contracted thereafter. Lateral antennae without tips, as long as palps; palpophores 3–4 times longer than palpostyles; median antenna thin, long, surpassing anterior prostomial margin, almost reaching tip of palpophore. Eyes brownish, anterior ones reniform, twice larger than posterior round ones. Nuchal organs depressed, lateral ciliated areas visible dorsally. Dorsolateral tubercles with 4 digitate lobes; ventral ridge with 10 large, round tubercles, midventral ones smaller].
Additional material. Philippines. Six specimens (3: MNHN Musorstom 3-135CP, and 3: ECOSUR 3079), Musorstom Expedition, Sta. 135 (11°58’ N, 122°02’ E), 486–551 m, in hexactinellid sponge fragment (Aphrocallistes sp.), 5 Jun. 1985 [5 complete, 17–28 mm long, 3–4 mm wide]. One specimen (MNHN Halipro 2-60), R/ V Tangaroa, Sta. 25 (25°16.64’ S, 170°23.69’ E to 25°17.45’ S, 170°23.93’ E), 1100–1348 m, 11 Nov. 1996 [30 mm long, 3 mm wide]
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Description. Best syntype (ZMH PE-318b) complete, distorted by preserving it with other organisms, compressed medially, bent laterally posteriorly. Body obconic, blunt anteriorly, wider anteriorly, tapered posteriorly (Fig. 43A); 28 mm long, 5 mm wide, 16 chaetigers; left parapodium of chaetiger 9 previously removed, right parapodium of chaetiger 8 removed for parapodial features. Tentacular and dorsal cirri mostly broken. Body dorsal and ventral surfaces pale; eyes dark brown.
Prostomium as long as wide, slightly wider anteriorly, lateral margins straight, convergent (Fig. 43B). Lateral antennae with ceratophores distinct, as long as prostomium, as long as palps; palpophores 2–3 times longer than palpostyles; median antenna slightly longer and thinner than lateral ones, markedly surpassing prostomial anterior margin, inserted between posterior eyes.
Eyes dark brown, anterior ones semilunar to reniform, twice larger than posterior round ones, slightly more distant to each other than posterior eyes; in lateral view, anterior and posterior eyes close to each other.
Nuchal organs lobes completely exposed, pale, depressed, oval, markedly separated middorsally; lateral ciliated bands not visible dorsally. Tentacular cirri without tips, longest ones reach chaetiger 6. Lateral cushions low, roughly bipartite along body; longitudinal striae not visible.
Peristomial dorsolateral tubercles wider than prostomium, each with four thick, digitate lobes, each twice longer than wide (Fig. 43C). Ventral ridge with nine thick digitate, as long as wide papillae, midventral ones slightly smaller.
Pharynx exposed (Fig. 43C, D). Upper jaw double, low, crescent shaped, lower jaw single, tapered. Anterior margin with 16 round, low papillae. Lateral vesicles round, projected laterally.
Dorsal cirri mostly broken, a few left as long as body width (Fig. 43E). Neuracicular lobes tapered, as long as wide or slightly longer than wide, tips sometimes contracted, directed upwards (Fig. 43E, inset). Neurochaetae about 30 per bundle, blades decreasing in size ventrally, bidentate, without guards; blades 3–4 times longer than wide (Fig. 43E, insets).
Posterior region tapered. Prepygidial segment with dorsal cirri 5–6 times longer than ventral ones. Pygidium with anus terminal, a single midventral anal cirrus left, reaching chaetiger 14.
Oocytes not seen.
Variation. The large anterior, 3–4 lobed hand-shaped tubercles, together with the ventral ridge of papillae are present even in the smallest syntype (20 mm long), as well as in the largest one (Fig. 44A, D). Eyes are dark brown, round, emarginate or reniform, sometimes even the posterior eyes are reniform; only one syntype has colorless eyes (and distorted head by compression). Median antenna scar always between posterior eyes. Nuchal organs lobes low diverging, round in all specimens; ciliated bands sometimes visible along lateral prostomial margins, or in the posterior nuchal organ margin. Pharynx features also similar in small to large syntypes (Fig. 44B, E): upper jaw double, lower one single, tapered. Parapodial features without major differences from small to large syntypes (Fig. 44C, F); neuracicular lobes tapered, slightly longer than wide, or up to 50% longer than wide, often with well defined tip, sometimes directed upward or downward (Fig. 44C, F, insets). Neurochaetae about 20–36 per bundle, number size dependent; many blades missing, bidentate, without guards.
Remarks. Leocratides filamentosus Ehlers, 1908 resembles L. jimii n. sp. from Japan because they have peristomial dorsolateral tubercles with thick digitate lobes. They differ, however, in their ventral pigmentation pattern and type of neuracicular lobes. In L. filamentosus venter is colorless, without pigmentation, and neuracicular lobes are longer than wide, continued into small mucros, whereas in L. jimii the venter shows a wide brownish band, especially along middle segments, and neuracicular lobes are as long as wide, and globose.
These hesionid worms were found in hexactinellid sponges which were recorded as Aphrocallistes bocagei Wright, 1870. This sponge was originally described with deep water specimens from Ireland to Cape Verde Islands (Wright 1870:5) and it would be difficult to be found also in Malaysia. One of the regional species, A. beatrix Gray, 1858, might correspond to the sponge species originally found having Leocratides specimens. These two species were regarded as synonyms in a recent publication (Reiswig & Kelly 2011:130), but they were regarded as distinct by Kent (1870:248) after a comparison of specimens and spicules from both species.
Distribution. Malaysia to the Philippines, in 468–1348 m, associated with hexactinellid sponges. The record by Rullier (1972: 58) was based upon poorly preserved specimens collected in the intertidal; his record is herein regarded as questionable because this is a deep-water species.
description: Published as part of Salazar-Vallejo, Sergio I., 2020, Revision of Leocrates Kinberg, 1866 and Leocratides Ehlers, 1908 (Annelida, Errantia, Hesionidae), pp. 1-114 in Zootaxa 4739 (1) on pages 76-79, DOI: 10.11646/zootaxa.4739.1.1, http://zenodo.org/record/3672547