Quantitative evaluation of the taxonomy of Pseudoschwagerina species from South China
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Abstract:
This paper reclassify 48 species of Pseudoschwagerina previously reported from South China. The measurements of the length, width of the shells, form ratios, radius of the proloculus, number of inner tightly-coiled and outer loosely-coiled volutions are entered into a database for quantitative analysis. Some holotype specimens stored in Nanjing Institute of Geology and Palaeontology have been re-measured. All species are projected onto a 3-D map using the software Grapher to show inter-species distances. Two groups can be recognized. One group is characterized by having fusiform to long fusiform shells, strong septal folding, and a form ratio greater than 2.0. The other group is characterized by having subspherical or thickly fusiform shells, weak to strong septal folding, and a form ratio less than 2.0. A further comparison of the inner volutions as well as the length of the shells of all species is made. Our analysis shows that species with longer shells usually contain long fusiform to fusiform inner shells and have less, normally 1–1.5, inner volutions, whereas those species with shorter shells contain short fusiform to subspheric younger shells and have relatively more, usually 2–4, inner volutions. Therefore, four and five subgroups are recognized in the first and second group, respectively, based on a comprehensive evaluation of the features of the younger shells, the size of the proloculous and the length of the shells.
