Systematic Taxonomy of Exceptionally Well-preserved Planktonic Foraminifera from the Eocene/oligocene Boundary of Tanzania

Diverse and extremely well-preserved assemblages of planktonic foraminifera were recovered from three drill holes through the Eocene/Oligocene boundary in southern Tanzania (Tanzania Drilling Project Sites 11, 12, and 17). The excellent state of preservation of the tests permits detailed investigation of wall textures and surface ornamentation, helping us to elucidate details of functional morphology and clarify the species-level and higher taxonomy of the group. We illustrate and discuss the taxonomy and phylogenetic relationships of fourteen genera and thirty-five species including three new species: Globoturborotalita barbula n. sp., Subbotina tecta n. sp., and Dentoglobigerina taci n. sp. Observations / proposals include (i) that Globigerinita unicava primitiva Blow & Banner is assigned to Catapsydrax unicavus, (ii) that Globorotalia (Turborotalia) permicra Blow & Banner is a pre-adult Globorotaloides, (iii) a description of a peculiar new wall texture in Globoturborotalita barbula n. sp., (iv) a revised understanding of Subbotina gortanii based on a new appreciation of the holotypes of Globigerina turritilina turritilina Blow & Banner and Globigerina turritilina praeturritilina Blow & Banner, (v) a revision of the genus Dentoglobigerina Blow to include some species that lack umbilical teeth, (vi) evidence for spine holes in several species of Dentoglobigerina, (vii) assignment of Globigerina prasaepis Blow to Dentoglobigerina as a distinct species related to D. venezuelana, and (viii) a discussion of the wall texture, apertural system and symmetry of Cribrohantkenina and its evolutionary origins.