Morphological abnormalities in benthic foraminifera caused by an attached epibiont foraminifer

Abstract. This study focused on the possible ‘parasitism-like’ relationship between the epibiont Cymbaloporetta sp. and basibiont benthic foraminifera including Agglutinella soriformis El-Nakhal, Adelosina carinatastriata Wiesner, Pseudotriloculina sp. and Spiroloculina indica Cushman & Todd from a sample collected off the east coast of Bahrain in the Arabian Gulf. There are no indications of preferential host selection, the epibiont seems to attach on to any available basibiont. However, constriction of the test and subsequent growth of the basibiont's chambers at the point of attachment of the epibiont might suggest an early link in their ontogeny. This biotic relationship has implications on the basibionts’ development and ontogeny that eventually results in the development of foraminiferal abnormalities. The finding of morphological test abnormalities caused by an epibiont in an unpolluted environment has important implications for the use of the abnormalities for pollution biomonitoring. Samples from other areas of the Arabian Gulf need to be studied in order to determine the background proportion of specimens with epiboints.