论奥陶纪三叶虫属Reedocalymene Kobayashi,1951(英文)

NOTES ON THE GENUS REEDOCALYMENE KOBAYASHI, 1951 (TRILOBITA, ORDOVICIAN)

由于建立Reedocalymene一属的模式种标本保存甚差 ,长期以来 ,这一属的概念一直不甚明了。研究了峡东地区庙坡组新发现的丰富且保存完好的ReedocalymeneexpansaYi材料 ,其中完整背壳系首次发现。新材料揭示了以往Reedocalymene的一些鲜为人知的背面和腹面形态 ,从而有可能对该属进行全面的修订。讨论了R .ex pansa的某些重要特征 ,如面线、前坑、腹边缘板、前舌以及壳面装饰等。R .expansa标本中的形态变异和保存差异表明 ,以往描记的所有产自峡东地区庙坡组的其他种都是它的晚出异名。目前归属于Reedocalymene的只有模式种R .unicornis和R .

For a long time, the concept of Reedocalymene has been unclear because its type species was erected on poorly preserved specimens. The abundant, well preserved material of Reedocalymene expansa Yi from the Miaopo Formation of the eastern Yangtze Gorges area in western Hubei, including the first recorded complete exoskeleton, reveals some dorsal and ventral morphologies that were little known previously in Reedocalymene. This material allows us to revise the genus comprehensively. Some of important features of R. Expansa, such as facial sutures, fossulae, rostral plate,anterior projection of cephalon, and exoskeletal sculpture, are discussed, providing a basis for understanding the genus until more is known about the type species. At present, only the type species, R. Unicornis, and R. Expansa can be assigned to Reedocalymene. The range of morphological variation and the observed differences in preservation in R. Expansa suggest that all other previously described species assigned to Reedocalymene from the Miaopo Formation in the eastern Yangtze Gorges area should be suppressed as junior synonyms of R. Ex-pansa.