Morphometrics of Heliolites （Tabulata） from the Late Ordovician, Yushan, Jiangxi, South China

The Upper Ordovician Xiazhen Formation in the Jiangshan-Changshan-Yushan （JCY） triangle area on the Zhejiang-Jiangxi provincial border, South China, is composed of a mixed carbonate-siliciclastic sequence representing various shallow-water platform environments. Highly diversified and abundant heliolitid coral faunas are recognized in the formation and occur over time and space in certain stratigraphic horizons and various lithofacies. Heliolites has been studied using multivariate morphometric analysis applied to differentiate species and evaluate intraspecific and interspecific variations. Ten morphological characters quantified by examination and measurement from transverse and longitudinal thin sections and statistically tested allowed selection of effective characters to discriminate species. Results of frequency histograms, correlation analysis and principle component analysis indicated that certain characters would be suitable for cluster analysis, which were performed on principle component score matrices obtained from the raw data set coordinated with coralla by all those characters. Five major clusters at a relative distance of five on the resulting dendrogram of Heliolites are regarded as morphospecies thus making valid taxa： Heliolites tashanensis Lin and Chow, 1977; Heliolites caracolica （Lin and Chow, 1977）; Heliolites columella （Lin and Chow, 1977）; Heliolites waicunensis Lin and Chow, 1977; and H. sinensis irregularis Lin and Chow, 1977. The discrimination of these morphospecies by the cluster analysis is verified by discriminant analyses and descriptive statistics.