A rich and diverse tanaidomorphan (Crustacea: Tanaidacea) assemblage associated with Early Cretaceous resin-producing forests in North Iberia: palaeobiological implications

摘要

The extinct tanaidomorphan diversity from Early Cretaceous Spanish amber, currently comprising 26 specimens, is reassessed. The fossil family Alavatanaidae Vonk & Schram, 2007, described from Spanish amber, is revised on account of new preparation of type specimens and the discovery of new material. The described tanaidomorphan taxa are classified within the superfamily Paratanaoidea. An emended diagnosis for Alavatanaidae is provided, as well as for the genera Alavatanais Vonk & Schram, 2007 and Proleptochelia Vonk & Schram, 2007, and their respective species Alavatanais carabe Vonk & Schram, 2007 and Proleptochelia tenuissima Vonk & Schram, 2007. Three new species, two of them classified in a new genus each, are described: Alavatanais margulisae Sanchez-Garcia, Penalver & Delclos sp. nov., Eurotanais terminator Sanchez-Garcia, Penalver & Delclos gen. et sp. nov. and Electrotanais monolithus Sanchez-Garcia, Penalver & Delclos gen. et sp. nov. Proleptochelia euskadiensis Vonk & Schram, 2007 is considered a junior synonym of A. carabe, and the genus Proleptochelia, together with its type and only species P. tenuissima, is left without familial placement within Paratanaoidea. Within this superfamily, Alavatanaidae is closely related to Leptocheliidae. Also, morphological variability due to sexual dimorphism in the studied paratanaoids has been determined. Multiple lines of taphonomic and palaeobiological evidence indicate that the Spanish amber tanaids were most likely inhabitants of wet or moist forest floors.