Polysyncraton amethysteum Van Name, 1902

Figure 4 D.

Stations. SC9; SC12; SC13; SS2; SS3; SS4; SS12; SR8; SR10; SR11; SR14; SR21; SR23; SR25; SB3.

Common on all kinds of substrates the colonies in large or small thin crusts are variable in a colour, always purple but more or less dark. The spicule density varies and they are sometimes absent or restricted to the colony surface. The Guiana material has been compared to specimens from Bermuda in the MNHN collection and all characters are similar. The thorax has a large atrial languet and a muscular thoracic appendage. The testis is divided into 4 lobes, rarely less, circled by the sperm duct in 4 to 5 turns. The larva 0.85mm in length (Fig. 4 D) has 3 adhesive papillae, 8 pairs of ampullae and one lateral bud. The spicules are variable in size: the largest do not exceed 50µm and are made of balls of needles.

P. amethysteum is present on both sides of the Atlantic Ocean and recorded as well in the Caribbean and along the Brazilian coast (Monniot F. 1984; Rocha, Moreno & Metri 2005).