Abstract

Morphological characters of twelve Recent species of Nodosariinae (Foraminifera) are revised, using a large number of specimens collected in the North Atlantic. The species are assigned to four genera: Dentalina Risso 1826, LaevidentalinaLoeblich and Tappan 1986, Nodosaria Lamarck 1812, and Pseudonodosaria Boomgaart 1949. One new species, Nodosaria haliensis is described. Previously unknown variation in the lamination pattern of the Nodosariinae test wall is described and some new terms are proposed to describe that variation. We continue to use the term monolamellar for septa made of a single layer, but use the term polylamellar, for septa made of two or more layers. The term plesio-polylamellar is proposed for forms with septa made of several layers, and which form secondary lamellae that envelope only some of the previous chambers. The term poly-monolamellar is replaced with a new term, ortho-polylamellar. We also discovered that only some, but not all of the primary layers in polylamellar septa continued to form secondary lamellae; this is referred to as a partial origin of secondary laminations. This is different from the well-known pattern in which all of the primary layers of a plesio-polylamellar septum continue and form what we refer to as a complete origin of secondary lamellae. We discovered that the lamellar structure of L. frobisherensis is somewhat variable even within the same specimen. The initial chambers are always ortho-monolamellar, but in later chambers the structure becomes plesio-monolamellar or even plesio-polylamellar, and the secondary lamellae can be either a partial or complete continuation of the primary lamellae of the septa. Species of Nodosaria are found to be atelo-lamellar, Laevidentalina are ortho-lamellar or plesio-lamellar and Dentalina and Pseudonodosaria are ortho-lamellar.

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