Preliminary research on the aquatic coleopteran, Coptoclava from the Early Cretaceous Jinju Formation

Abstract

The family Coptoclavidae is an extinct aquatic beetle group which occurs in the Mesozoic strataof Eurasia. The family is characterized by the presence of two pairs of eyes which were used for both aerial andaquatic vision as in the extant Gyrinidae. New coptoclavid fossils have been discovered from the Lower CretaceousJinju Formation in the Jeongchon section, Jinju, Gyeongsangnam-do, and the two Gwanghyeon 1-ri and 2-risections, Gunwi, Geyongsangbuk-do. Numerous larvae were found in the three sections and a few imagos in theGwanghyeon sections. The exceptionally long forelegs of the larva and imago are reminiscent of the long forelegof Coptoclava longipoda Ping, 1928 from the Lower Cretaceous of China, and thus the coptoclavids from the JinjuFormation are assignable to the genus Coptoclava. However, the abdominal outline of Coptoclava from the JinjuFormation is distinguishable from those of the reported specimens of Coptoclava longipoda. Coptoclava isconsidered as a large predator in the aquatic ecosystem of the Lower Cretaceous. The dominance of Coptoclavaindicates that the entomofauna of the Jinju Formation is closely comparable to that of the Jehol Biota of China.Because the age of the Jinju Formation is much younger than the Jehol Biota, the entomofauna of the Jinju Formationwould play an important role in understating the development of East Asian entomofauna after the time of the JeholBiota.