Fossil evidence of extended brood care in new Miocene Peracarida (Crustacea) from Mexico

摘要

Currently, the Peracarida contains important crustacean groups, such as Isopoda or Amphipoda, that incubate their young in a brood pouch. However, the fossil record of Peracarida is rather poor and the evolutionary pathways leading to their remarkable reproductive strategy are incompletely documented. In this study, we describe the first fossil evidence of extended brood care in Peracarida, based on two Oniscidea (Isopoda) gravid females preserved in Miocene Chiapas amber from Mexico. These adult specimens are preserved with several mancas at a terminal stage of development, some remaining trapped in the marsupial structures of the adults. The well-preserved adults and mancas are described and assigned to the family 'Philosciidae', currently one of the most diverse and abundant oniscidean families in tropical biotopes and wetlands habitats. A new genus - Aquitanoscia gen. nov. - and two new species - Aquitanoscia chiapasensis sp. nov. and A. matemus sp. nov. - are figured and described. Finally, the physiological, morphological and behavioural conservation of the reproductive strategies of the Peracarida is discussed.