The foraminiferal genera Pararotalia, Neorotalia, and Calcarina: taxonomic revision

Scanning electron microscopy of the architecture of Rotalina inermis Terquem, 1882, the type-species of the genus Pararotalia Le Calvez, 1949, and of Rotalia mexicana Nuttall, 1928, the type-species of the genus Neorotalia Bermudez, 1952, reveals that both taxa have in common: 1) an umbilical bowl closed by either a single or a compound umbilical plug; 2) an interiomarginal extraumbilical aperture, restricted by a toothplate that protrudes with a free edge into the aperture and forms an umbilical spiral canal; and 3) a septal flap and intraseptal interlocular spaces. Rotalia mexicana, however, also possesses an enveloping canal-system, similar to that found in the Calcarinidae. For this reason Neorotalia must be regarded as a valid distinct genus, not synonymous with Pararotalia, as proposed by some authors. Calcarina calcar d'Orbigny, 1839, variously placed by authors in Rotalia Lamarck, 1804, in Pararotalia Le Calvez, 1949, and lately again in Calcarina d'Orbigny, 1826, is shown to possess the same basic architecture as Neorotalia and is placed, consequently, into this latter genus. Irregular supplementary apertures occurring in N. calcar are not considered of generic value and neither are they regarded as indicating a relationship with Nautilus spengleri Gmelin, 1788, the type-species of Calcarina. The latter, although characterized by a complex enveloping canal-system, possesses primary multiple interioareal main apertures, surrounded by thick rims, as well as a small umbilical plate, but lacks a toothplate with a free edge. For comparison, Pararotalia spinigera (Le Calvez, 1949) and Neorotalia viennoti (Greig, 1935) were also studied. The subfamily Pararotaliinae Reiss, 1963, is emended to include the canal-system as a characteristic feature. A glossary of selected terms is appended.