Apionsoma trichocephalus Sluiter, 1902

Adrianov, Andrey V. & Maiorova, Anastassya S., 2012, Peanut worms of the phylum Sipuncula from the Nha Trang Bay (South China Sea) with a key to species, Zootaxa 3166, pp. 41-58 : 50-51

Apionsoma trichocephalus Sluiter, 1902

( Fig. 4 E–F)

Material. Nha Trang Bay: Diamond Bay, intertidal, coral rubble, 1 specimen.

Description. Trunk spindle-shaped, 3–4 mm long, 1 mm wide; very thin introvert 10 X longer than the length of the trunk. Fold-like dorsal arc with 6 minute rudimentary tentacles, usually invisible in the dissecting microscope. Hooks scanty, barely visible, without accessory combs of spinelets, arranged in one incomplete ring.

Discussion. This species differs from other representatives of the subgenus Apionsoma by having scanty hooks lacking spinelets and a reduced tentacular apparatus.

Apionsoma trichocephalus is a circumtropical species, known from the Atlantic, Indian and Pacific Oceans. It inhabits sandy and muddy sediment from the intertidal to bathyal depths, and has been recorded in the West Pacific from New Zealand to Japan.

Figures

FIGURE 4. A. Antillesoma antillarum, lateral view, introvert everted. B – D. Apionsoma misakianum. B) lateral view, introvert everted; C) lateral view, introvert retracted; D) hook. E – F. A. trichocephalus. E) head (white arrowhead - rudimental tentacle on dorsal arc.); F) hook. Scale bars: A – B, 5 mm; C, 2 mm; D, 20 µm; E, 100 µm; F, 20 µm.