(Phascolosoma) arcuatum (Gray, 1828)

Acd, 2000, Sipuncula from Hainan Island (China), Journal of Natural History 34, pp. 2187-2207 : 2194-2195

Phascolosoma (Phascolosoma) arcuatum (Gray, 1828)

Material. Haikou, 12 March 1992, 38 specimens.

Description. Trunk 46±83 mm long and 8±11 mm wide. Introvert slightly longer than the trunk. The integument is of a light yellow colour with many dark spots at both trunk ends which correspond to papillae. Hooks, 65±85 m m in height, are arranged in more than 50 rings and curve-shaped without a secondary tooth on the concave side. Internally, the clear streak is simple with a great expansion basally (®gure 3b, c). Longitudinal and circular musculature divided into bands. Retractor muscles are discernible as four short roots split oOE from a single column. Two nephridia which are shorter than the trunk length.

Discussion. This species is characterized by the simplicity of its hooks, in comparison with those of the remaining species of Phascolosoma, and the arrangement in bands of both types of corporal musculature (longitudinal and circular). The

external aspect of the worm is also diagnostic at ®rst sight due to its colour as well as by the large and outstanding papilllae on both trunk ends.

There are many records from the Indian Ocean and the Western Paci®c, having been previously recorded from the area investigated, from HaõÈphong, Gulf of Tonkin (Leroy, 1936), Indochina (Leroy, 1942), Hainan (Chen, 1963), Zhanjiang, South China (Murina, 1964), coasts of South China (Li, 1989) and South China Sea (Li et al., 1992b). The specimens of this collection were purchased in a local market; in fact, a dish which is very appreciated by the inhabitants of the China coasts is made with this species (Chen and Yeh, 1958) (hence the speci®c name P. esculenta used for one of its junior synonyms). The species tolerates long periods out of the water at around the high tide line. They are often found in brackish waters as well as in mangrove estuaries.

2014 Material. Phascolosoma Lingchang, 10 (Phascolosoma April 1992, one) meteori specimen (HeÂrubel., 1904) February than Internally Description the trunk, there.. is Hooks Trunk a wide in 13 clear fewer mm streak long than and which 50 2 rings mm almost wide, with. ®lls The a the maximum introvert hook surface is height slightly, sometimes of shorter 25 m m. 14 a small triangle in the convex side of the hook is also visible (®gure 4a±c). Large 34 papillae, conical in shape and dark pigmented, are present on both trunk ends.: 02 About 18 anastomosing bands of longitudinal musculature. Four retractor muscles at and one nephridium (located on the right side) 4.5 mm in length. Nephridiopore a] little behind the anus. Bath Discussion. The size of the hooks (<25 m m) and their internal structure are of characteristic of the species, being apparent in the specimen investigated. The University (presence teratological except The present for of the a disposition unique specimen hooks, nephridium which or ®ts a well consequence were with, on not the the found Stephen of right its). loss side However and during of Edmonds the, the handling body generic (1972 wall.), description revision is either of a [by Cutler and Cutler (1990) included some new features in the description of the Downloaded were species pre-anal vesicular not, such papillae swellings observed as the in on in shape clusters the our surface of specimen of the two papillae of to, the the ®ve contractile (hooks. small They domes helped also vessel demonstrated) to and. Although identify the arrangement it these the. Nevertheless existence characters of the of,

we had some doubts in the identi®cation as we had only one specimen at our

disposal.

The species, hitherto, was known from the Red Sea (Wesenberg-Lund, 1957)

and the Gulf of Aden (HeÂrubel, 1904; Stephen, 1941). The present record of this

species at Hainan Island means a provisional expansion of its known range, being

the ®rst record for the Paci®c Ocean.