Abstract

The status of the two subgenera Eulepidina and Nephrolepidina of the genus Lepidocyclina is debated by many. The nature and arrangement of periembryonic chambers are considered to be features of primary importance in classification. These, however, are not often visible for several reasons. In view of this, in the present study the nucleoconch shapes of the two subgenera are analyzed for comparison. Well-prepared, oriented sections with periembryonic chambers clearly visible in the two subgenera are used for shape analysis of nucleoconchs. The examined species include L. (E.) ephipoides, L. (N.) isolepidinoides and L. (N.) sumatrensis from the Oligocene-Miocene succession of Kutch. Results from closed from Fourier analysis revealed that the nucleconchs of the two subgenera distinctly differ in shape. The 3rd, 4th and 5th harmonics are found to be significantly different in the power spectrum of the two subgenera. It is therefore concluded that Eulepidina and Nephrolepidina are taxonomically valid subgenera. The Fourier shape analysis is also carried out for the nucleconchs of phylogenetically related species Lepidocyclina (Nephrolepidina) isolepidinoides, and Lepidocyclina (Nephrolepidina) sumatrensis. The results show that this method is also effective at species level differentiation.

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