Acryptolaria pseudoundulata n. sp.

(Figs 25; 30; 32H; Table 26)

TYPE MATERIAL. — Loyalty Islands. MUSORSTOM 6, stn DW 457, 21°00.42’S, 167°28.71’E, 353 m, 20.II.1989, several stems on coral; 1 stem 50 mm high, holotype (MNHN-Hy.2009-0172); several incipient stems, paratype (RMNH-Coel. no. 31527).

ETYMOLOGY. — The specific name pseudoundulata refers to the close resemblance to A. undulata n. sp.; the species name is an adjective, corresponding in gender with the (feminine) name of the genus.

ECOLOGY AND DISTRIBUTION. — Acryptolaria pseudoundulata n. sp. was collected at a depth of 353 m in the Loyalty Islands area where it was found epibiotic on coral.

DESCRIPTION

Stem up to 50 mm high. Branching scarce (Fig. 32H) and irregular, more or less in one plane. Branches up to second order have been observed; one primary branch has three secondary branches. Branches roughly straight (Fig. 25A); anastomoses present.

Hydrothecae alternately arranged in approximately one plane (Fig. 25A), with a double bend (Fig. 25) and consequently with undulating walls: strongly curved outwards where it becomes free from the axis and slightly turned upwards soon after. The adcauline wall is convex at the adnate part and slightly concave or straight at its free portion. Abcauline wall straight or slightly convex at basal third, then with a strongly marked inflection point, forming a shallow embayment followed by an unconspicuous hump, and later on slightly concave or straight. Hydrothecal diameter largest in adnate part, but markedly decreasing at base. Diameter of free part of hydrotheca slightly narrowing towards the rim. Hydrotheca adnate for about half its adcauline length (adnate/free ratio 1.1). Hydrothecal aperture circular, oblique, directed upwards, forming an angle of c. 30° with long axis of branch. Rim even, frequently with renovations.

Large nematocysts relatively very large and fusiform (Fig. 30).

Coppinia not found.

REMARKS

Acryptolaria pseudoundulata n. sp. is undoubtedly allied to A. undulata n. sp.; the relationship is discussed below, when dealing with the latter. It also resembles A. novaecaledoniae n. sp. in the shape of the hydrothecae, but in that species the hydrothecae are much more strongly directed outwards, the branches are straight and the nematocysts are much smaller (17.7 × 4.7 µm).