A NEW LARGE AGGLUTINATED FORAMINIFER (ARBORAMMINIDAE N-FAM) FROM AN OLIGOTROPHIC SITE IN THE ABYSSAL NORTHEAST ATLANTIC

A new, unusual agglutinated foraminifer, Arborammina hilaryae gen. sp. nov., is described from an abyssal (4950m) site on the Madeira Abyssa l Plain and assigned to a new family. This large (1.5-2 cm long) foram inifer consists of a basal swelling buried within the sediment, and an erect stem which projects up into the water and divides distally into a semi-circular crown of branching arms. There is no obvious test lum en, instead the protoplasm probably occupies globigerinacean tests inc orporated within the stem and basal swelling. In addition, extensive o rganic, possibly protoplasmic, sheets and strings ramify throughout an d cover the surface of the test. The occurrence of a large, arborescen t foraminifer at the relatively oligotrophic abyssal site is notable. Its external morphology suggests that A. hilaryae is a suspension feed er, and possibly an osmotroph.