Comprehensive Description

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Adult Lt 244–272 µm; LPh 48–53 µm to PhJIn at U20 (Fig. 5). Body flattened ventrally, vaulted dorsally, comprised of head that is crescent-shaped anteriorly, with laterally directed lobes that have rounded tips and a protruding mouth, with a knob-shaped cephalic pestle organ (L 7 µm) on each side that lies largely exposed beneath the rear of the head lobes; neck constriction slight, marking the pharyngeal pore openings; neck constriction slight; the trunk is parallel-sided trunk, narrowing gradually in the rear, ending in a long, narrow caudal peduncle, with a bifurcate apex that indents medially to U90. Width of head /lobes /neck /trunk /caudal base are as follows: 28 /38 /21 /26–28 /7 µm at U08 /U04 /U18 /U31–U55 /U73, respectively. Glands are of two types, one with 4 per side, oval in shape (diam 4–6 µm) at U05 /U13 /U26 /U62 and a solitary medial gland on the caudal peduncle at U87, the other with 3 per side, ragged in shape and more refringent (diam 3 µm) at U21 /U42 /U65.  Adhesive tubes: TbA 1 per side (L 18 µm), comprising a long (6 µm) duo-gland tube extending forward from a heavy tapering base that inserts directly on the body surface, tubes being highly mobile and able to project laterally; TbL are absent; TbP 3 per side: one longer (L 12 µm) arising proximally from the caudal peduncle, and two shorter (L 5 & 9 µm) arising from the bifurcate tips of the 80 µm long pedunculated caudum.  Ventral ciliation: Head lobes bear a transverse row of cilia ventrally (L 8µm); head bears numerous cilia (L 10–25 µm) frontally, laterally and dorsally; sensory hairs 7 each per side occur in lateral (L 8–10 µm) and dorsal (L the first 26–28, others 14–16 µm) columns, lateral cilia occurring singly, dorsal cilia occurring in pairs, all spaced more or less evenly from U08 to U70, behind which are single lateral hairs on either side at U76 and U90 on the caudal peduncle. Locomotor ciliation runs in paired longitudinal bands from the TbA rearward, joining behind the anus and continuing as a unified band onto the caudal peduncle, with a patch lying just before the bifurca.  Digestive tract: Mouth diameter narrow (2 µm), protruding forward from the anterior head curvature; a goblet-shaped buccal cavity is moderately cuticularized; pharynx narrow, its basal pores located at the level of the neck constriction, and only detected with maturity; intestine narrow, broader in front, narrowing markedly half way along its length, but with a bulge around the anus, its lumen being fringed by actively-beating cilia; anus ventral at U68.  Reproductive tract: Simultaneous hermaphrodites; testes paired, but uneven in origin, along the fore-gut, its vasa deferentia extending rearward, but their termini not seen; sperm (L 25 µm) show half a spirally thickened head and half a flagellum; ovaries, with several (3–7) immature ovules, are located along the rear mid-gut, with the most mature ova developing medially forward between ovary and testes; an ovoid frontal organ bearing active sperm occurs opposite the largest ovum on the right side.


Creative Commons Attribution 3.0 (CC BY 3.0)

© William D. Hummon

Source: ZooKeys

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