Taxonomic and Nomenclatural Justification For the Triassic Meandrospiral Foraminiferal Genus Citaella Premoli Silva, 1964

Abstract

AbstractTaxonomy and nomenclature of Triassic meandrospiral foraminifers have been confused for a long time and they have been misinterpreted to relate to Cretaceous Meandrospira in most studies. We comprehensively reviewed their research history, considering morphology, phylogenetic relation, taxonomy, and nomenclature. This allowed us to confirm their original porcelaneous wall composition based on well-preserved specimens, and to legitimize the use of the generic name Citaella Premoli Silva, 1964 for Triassic meandrospiral foraminifers. Citaella is here redefined as a miliolate genus having a porcelaneous shell and typical meandrospiral arrangement in its tubular deuteroloculus. The genus is restricted in the late Early to early Middle Triassic (Olenekian–Anisian) of the Tethyan realm. It was likely derived from a cornuspiroidean ancestor in earliest Triassic time, although the ancestral taxon is still unclear. Citaella gave rise to two descendant genera, Meandrospiranella and Turriglomina, in the early–middle Anisian. These three taxa formed a single phylogenetic clade in the Triassic, to which the subfamily Turriglomininae Zaninetti 1987 is best applicable. Citaella is phylogenetically distinct from its homeomorphic miliolate genera Streblospira in the Early Permian and Meandrospira in the Early Cretaceous, although they have the same wall compositions and very similar arrangement patterns in deuteroloculi. After scrutinizing literature, we recognized four distinct species in the genus Citaella including one with questionable generic assignment. We also made taxonomic emendation of the subfamily Turriglomininae and the genus Citaella, and demonstrated nomenclatural precedency of Citaella pusilla over other synonymous species that were proposed simultaneously in the same article.