Palaeobiogeography and evolutionary patterns of the larger foraminifer Borelis de Montfort (Borelidae)

The palaeobiogeography of the alveolinoid Borelis species reveals the evolutionary patterns leading to the two extant representatives, which occur in shallow-water tropical carbonate, coral reef-related settings. Type material and new material of fossil Borelis species, along with Recent specimens were studied to assess their taxonomic status, species circumscriptions (based on proloculus size, occurrence of Y-shaped septula, and the index of elongation), palaeobiogeography and evolutionary dynamics. The species dealt with here are known from exclusively fossil (B. pygmaea, B. inflata, B. philippinensis, B. melo, B. curdica), and from fossil and modern (B. pulchra, B. schlumbergeri) specimens. For the first time, fossil and Recent Borelis specimens are illustrated via micro-computed tomography scanning images. Depending on the occurrence of Y-shaped septula, two lineages are distinguished. Deriving from the middle–upper Eocene Borelis. vonderschmitti, the first lineage includes B. infla...