Foraminifera note details

Globigerinellita Translation Le Coze: 20/03/2019 To the morphology, systematics and Phylogeny of the Planomalinids Kopaevich, L. F.; Maslakova, N. I. Research on the morphology of Foraminifera tests belonging to the family Planomalinidae allowed to trace transformation characters in various morphological features in the process of development of the test. Three ontogenic stages were established: embryonic, juvenile and adult. The embryonic stage (first chamber and first whorl) is identical for all the representants of the family and shows a trochoidal structure. At the juvenile stage (second whorl) following a deviation, the test acquires a plano-spiral structure and an equatorial position of the main aperture; at this same stage the features inherent to the genus or group of genera appear (type of septal sutures, peripheral keeled edges, relict apertures). Adult stage (third whorl) is characterized by the occurrence of the features at both generic and species levels through an anabolic pathway; the former include the overgrowing of relict aperture, radial stretching of chambers and a double main aperture; Species features are the nature of the spiral, the shape of the chambers and the nature of their growth, the width of the umbilicus and the degree of curvature of the septal sutures. Analysis of the morphology of the shells made it possible to obtain some new data concerning the genetic relationships between the genera of the family under consideration. The proposed phylogenetic development scheme consists of two morphologically distinct branches. The first branch contains the genera Globigerinelloides and Planomalina, whose developments are mainly limited to the early Cretaceous time. The second branch consists of three genera, distributed mainly in the Late Cretaceous: Globigerinellita gen. nov., Biglobigerinella Lalic., Hastigerinoides Bronn. The new genus (type species Rotalia aspera Ehrenb.), is separated from the genus Globigerinelloides from which it is distinguished by the absence of a septal thickening by the shape of the apertural lips, covering relict apertures. Those genera should be separated from the family Planomalinidae and included in an independent suprageneric taxon. Kopaevich, L. F.; Maslakova, N. I. (1980). К морфологии, систематике и филогении планомалинид - To the morphology, systematics and phylogeny of planomalinids. Materialy VIII mikropaleontologicheskogo sovetshchaniya. Elm Publisher, Baku. 62-63 (in Russian).
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2019-03-25 17:47:01Z