Acanthodasys flabellicaudus
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Ordo: Macrodasyida
Familia: Thaumastodermatidae
Genus: Acanthodasys
Name
Acanthodasys flabellicaudus Hummon, William D., 2009 – Wikispecies link – Pensoft Profile
- Acanthodasys flabellicaudus Hummon, William D., 2009, Zootaxa 2278: 53-56.
Diagnosis
Diagnosis: Adult Lt 592 Μm; PhJIn at U 27. Head end nearly squared off; trunk broadens somewhat in the pharyngeal region, becomes obesely broad in the mid-intestinal region, then narrows in two stages to the rounded caudum. Glands 30–32 per side, most dense behind the anus. Epidermis is covered with small T-shaped uniancres, similar both dorsally and ventrally, having no intervening cuticular elements; only the ciliated patches of locomotor cilia are free of uniancres. TbA 5 per side, inserting directly on the body, projecting forward to diagonally outward; TbVL 12 per side, 9 at U 18 -U 57, with 3 at the rear of the pharynx, and 6 in the fore intestinal region, the remaining 3 at U 73, U 90 and U 94, the final 2 being in the postanal region; TbDL 3 per side, asymmetrically placed at U 29 -U 59; TbL per se /TbV absent; TbP 6, longer medially than laterally, occur on the rounded rear of the caudum. Locomotor ciliature: a field of ciliary patches, interspersed with the ventral uniancres. Mouth terminal, as broad as the fore end of the body, rim bears a corona of cilia; non-cuticularized buccal cavity narrows quickly; narrow pharynx has inconspicuous basal pharyngeal pores; intestine broadest in the middle, narrowing gradually fore to aft; anus at U 89. Hermaphroditic; testes are bilateral in this subfamily, beginning just behind the PhJIn, with vasa deferentia continuing rearward before joining medially at U 73 and leading rearward to an irregularly shaped longitudinal caudal organ with a medial canal and some glandular material; a developing egg and 2 germinal vesicles occur in the mid-intestinal region; a spherical frontal organ is hyaline and bears motile sperm; another spherical structure bearing small round objects occurs between the germinal vesicles and the frontal organ; a dorsal rosette occurs in the fore-intestinal region at U 38.
Description
Description: Adult Lt 592 Μm; LPh 158 Μm to PhJIn at U 27 (Fig. 3 A, B). Body long as an adult, ventrally flattened, dorsally vaulted; head end nearly squared off; trunk broadens somewhat in the pharyngeal region, becomes obesely broad in the mid-intestinal region, then narrows in two stages to the rounded caudum. Widths at and just behind mouth/PhJIn/mid-intestine/anus/caudum and locations along the length of the body are as follows: 44,40 / 62 / 92 / 40 / 15 Μm at U01,U02/U 27 /U 60 /U 89 /U 97, respectively. Glands 30–32 per side (2–4 Μm diam.) are scattered in lateral and dorsal columns, most densely clustered behind the anus. Cuticular Armature: Epidermis is covered with small T-shaped uniancres (Fig. 3 E), of similar size ventrally and dorsally (L 8 Μm), having no intervening cuticular elements. Only the ciliated patches of locomotor cilia are free of uniancres. Adhesive tubes: TbA 5 per side (L 5–7 Μm), in a broad, shallow arc, inserting directly on the postoral body surface at U02-U03 and project forward to diagonally outward; TbVL 12 per side (L 12–14 Μm), with 9 at U 18 -U 57, most symmetrically placed, 0 of these in the fore pharyngeal and 3 in the rear pharyngeal regions, and 6 in the fore intestinal region, the remaining 3 occurring symmetrically at U 73, U 90 and U 94, the final 2 being in the postanal region; TbDL 3 per side, asymmetrically placed at U 29 -U 59; TbL per se /TbV are absent; TbP 6 (L 14–17 Μm), longer medially than laterally, occur on the rounded rear of the caudum. Ciliation: Mouth rim bears a corona of cilia (L 8–12 Μm); sensory hairs arise in lateral columns on either side of the body (L 6–10 Μm), numbering c. 45 each. Ventral locomotor ciliature forms a field of ciliary patches (cilia L 10 Μm), interspersed with the ventral uniancres (Fig. 3 D). Digestive tract: Mouth terminal, as broad as the fore end of the body, width 39 Μm; non-cuticularized buccal cavity narrows quickly; narrow pharynx has inconspicuous basal pharyngeal pores; intestine is broadest in the middle, narrowing gradually to the rear; anus is at U 89. Reproductive tract: Testes are bilateral in this subfamily, beginning just behind the PhJIn, with vasa deferentia continuing rearward before joining medially at U 73 and leading rearward in the hind-intestinal region to a longitudinally oriented caudal organ of irregular shape that has a medial canal, followed to the rear by some glandular material; a developing egg (39 x52 Μm) and 2 germinal vesicles occur in the mid-intestinal region; a spherical frontal organ occurs that is hyaline and bears a cell-like structure and some motile sperm; another spherical structure with a dozen small round objects occurs between the germinal vesicles and the frontal organ; a dorsal rosette occurs in the fore-intestinal region at U 38. Ecology: Sparse in frequency of occurrence (less than 10 % of samples), scarce in abundance (3–5 % of a sample); sublittoral in fine, medium-well sorted, clean sand, 5.0 m water depth, 0–10 cm depth. Geographical distribution: MED: EUROPE:ITALY: Campania Archipelago {Isola d’Ischia: Spiaggia degli Inglesi^ 40 °, 45 ’N/ 13 °, 56 ’E [2 -videos]}
Discussion
Remarks: The description of Acanthodasys flabellicaudus n. sp. is taken from two specimens, both from the same location. One (WDH video # 9, Fig. 3 A,B, a holotype, ICZN Article 73.1.1) is a mature adult. The other (WDH video # 10, Fig. 3 C,D, a paratype, ICZN Article 72.4.5) is a subadult: Lt 428 Μm; LPh 152 Μm, with TbA 4 or 5 per side, TbVL 7 per side, TbD 3 per side, and TbP 6 per side.
Etymology
Etymology: The species is named after the small fan-shaped (Latin flabellum) array of rear (Latin cauda) adhesive tubes. Taxonomic affinities: There are currently eight described species of Acanthodasys, including: Acanthodasys flabellicaudus n. sp., the latter being the only species having a rounded rather than a furcated caudum, together with TbA 5 per side, TbDL 3 per side, and T-shaped uniancres of similar size dorsally and ventrally, with no additional elements in between.
Taxon Treatment
- Hummon, William D.; Todaro, Antonio; 2009: Italian marine Gastrotricha: VI. Seven new species of Macrodasyida, Zootaxa 2278: 53-56. doi
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