Exceptionally preserved cryptoniscium larvae - morphological details of rare isopod crustaceans from French Cretaceous Vendean amber

Abstract

Epicaridea is an ingroup of Isopoda that comprises only parasitic crustaceans. Within parasitic isopods, epicarideans represent a special case: throughout their ontogeny they switch from a small intermediate host (copepod) to a final host (various larger crustaceans), and develop through distinct larval phases (epicaridium, microniscium and cryptoniscium). Young males of some species retain a larval morphology. Recent findings of fossil epicarideans in amber from the Miocene of Mexico consisted in the only epicaridean body fossils, until one specimen has been figured from Cretaceous amber from France. Here we provide a detailed analysis of this specimen and 20 more specimens from the same locality. The presented specimens represent the oldest occurrence of epicaridean body fossils, extending their fossil record by 67 million years.