Two middle Cambrian trilobite genera, Cyclolorenzella Kobayashi, 1960 and Jiulongshania gen. nov., from Korea and China

Abstract

Cyclolorenzella is an important member of the middle Cambrian trilobite faunas in China and Korea. Morphometric analysis based on well-preserved new material assignable to Cyclolorenzella from China and Korea reveals that most of the species assigned previously to Cyclolorenzella in China are morphologically distinct from the genotype. Accordingly, the new genus Jiulongshania, with J. acalle (Walcott, 1905) as type species, is proposed to accommodate the following species: J. acalle, J. regularis (Walcott, 1906), J. rotundata (Resser & Endo in Endo & Resser, 1937), J. longispina (Wittke & Zhu in Zhu & Wittke, 1989), J. acuta (Duan in Duan et al., 2005) and J. longa sp. nov. Species tentatively transferred to Jiulongshania are J.? subcylindrica (Chu, 1959), J.? yentaiensis (Chu, 1959), J.? humilis (Zhang in Qiu et al., 1983), and J.? latisulcata (Zhang in Qiu et al., 1983). This taxonomic revision results in only two species remaining in Cyclolorenzella, the type species C. quadrata (Kobayashi, 1935) and C. convexa (Resser & Endo in Endo & Resser, 1937). Jiulongshania has a relatively long stratigraphic range from the Damesella–Yabeia Zone to the Blackwelderia Zone of China, whereas Cyclolorenzella is restricted to the stratigraphically younger Drepanura Zone in China and Korea.