Larger porcelaneous foraminifera with a common ancestor: the Neogene Indo-Pacific Flosculinella and Alveolinella (Alveolinoidea)

Abstract

Only two alveolinoid genera, Borelis de Montfort, 1808 and Alveolinella H. Douvillé, 1907 thrive in present-day Indo-Pacific coral-reef settings. The former is widespread from the Western (Red Sea) to the Central Indo-Pacific and Caribbean Sea coasts, whereas the latter occurs in the Central and Eastern Indo-Pacific area. A third Indo-Pacific alveolinoid genus, Flosculinella Schubert in Richarz, 1910, is exclusively fossil. New fossil and Recent material and a type collection were analysed to assess the taxonomic status of Flosculinella and Alveolinella species and understand alveolinoid phylogeny in the Indo-Pacific area.The latest Oligocene–middle Miocene Flosculinella globulosa, the early–middle Miocene F. reicheli, F. bontangensis, F. cucumoides, Alveolinella borneensis and the middle Miocene–Recent A. quoyi are herein circumscribed in terms of shell length, diameter of the proloculus, whorl number of the first attic occurrence, and number of supplementary chamberlets in the attic floor per chamberlet in the main floor. The occurrence of the preseptal passage only and Y-shaped septula in Borelis schlumbergeri, Flosculinella and Alveolinella are characters of phylogenetic significance. Oligocene–early Miocene Borelis philippinensis is inferred as the common ancestor of these taxa.The diversification of Flosculinella and Alveolinella occurred in the Coral Triangle of Southeast Asia during the early–middle Miocene. The northernmost occurrence of the Tortonian–Recent A. quoyi, widespread from Central to the Eastern Indo-Pacific areas, is in the Ryukyu Islands.