Structure, taxonomy and ecology of Astrammina triangularis (Earland), an allogromiid-like agglutinated foraminifer from Explorers Cove, Antarctica

Astrorhiza triangularis (Earland) is transferred to the genus Astrammina based on structural and molecular analyses of abundant material collected from Explorers Cove, McMurdo Sound, Antarctica. This large, unilocular agglutinated species was previously known from only 14 specimens collected on the Atlantic side of the Antarctic continent. It resembles Astrammina rara in possessing an allogromiid-like sarcode (cell body) and laminated theca surrounded by a large intratest space. Astrammina triangularis makes an important contribution to foraminiferal biomass in Explorers Cove. Live specimens are orientated upright in the sediment and, in laboratory experiments, feed on algal and metazoan prey.