Sipunculans and echiurans from the deep Angola Basin

Abstract

Sipunculans and echiurans collected by the “DIVA 1” expedition by RV Meteor (Cruise M48/1) to the deep‐sea bottom of the Angola Basin are recorded. Seven species from five genera and two separate phyla are recognized; only the echiuran Pseudoikedella achaeta has not been recorded hitherto in the southern sector of the Atlantic Ocean. A gradient analysis using redundancy analysis (RDA) under the CANOCO package indicates the existence of a neat latitudinal gradient of sipunculans along the Angola Basin from the southernmost stations towards the northern ones. The local abundance of abandoned horny tubes of polychaetes at some of the sampling sites of the northernmost stations explains the dense aggregations of Nephasoma diaphanes. This species exhibits an opportunistic lifestyle inside empty polychaete tubes on the abyssal plains of the Angola Basin.