Palaecological and ichnological significance of microborings in Quaternary foraminifera

A large number of Quaternary foraminiferans, collected from several localities worldwide, show evidence of bioerosion in their tests. These bioerosion traces confirm that predation and parasitism of benthic foraminiferans are widespread phenomena in modern and fossil marine environments. Also, single borings related to different chambers in the tests of planktonic foraminiferans support the hypothesis that one or several unknown planktonic organisms prey on living foraminiferans. A healed boring observed on the test of a planktonic foraminiferan indicates that at least some planktonic foraminiferans survive the attack of the unknown predator. The occurrence of one of the traces, Fossichnus solus igen. et isp. nov., suggests that its distribution is controlled by environmental parameters. Fossichnus solus isp. nov. is distinguished by a single groove having a circular to oval outline and most likely represents an attachment structure. Alternatively, as F. solus isp. nov. forms part of a developmental sequence that may result in Oichnus simplex, it could be interpreted as an abandoned predation trace. Other bioerosion structures are recorded for the first time. A sieve-shaped boring is left in open nomenclature because of its rarity. A crescent-shaped hole and a groove-shaped hole are left in open nomenclature as Oichnus aff. asperus and O. aff. paraboloides, respectively. Fossichnus solus isp. nov. is quite common within its temporal and geographical area of distribution. Therefore, this ichnospecies has a potential usefulness as a palaeoecological marker. However, the sieve-shaped boring, Oichnus aff. asperus, and O. aff. paraboloides all occur very rarely and therefore are of limited palaeoecological use at present.