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

Abstract

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 Sánchez-García, Peñalver & Delclòs sp. nov., Eurotanais terminator Sánchez-García, Peñalver & Delclòs gen. et sp. nov. and Electrotanais monolithus Sánchez-García, Peñalver & Delclòs 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.

http://zoobank.org/urn:lsid:zoobank.org:pub:DC943B18-A01C-412C-8378-C644FEFDA716

Keywords:

• Tanaidomorpha
• Alavatanaidae
• Mesozoic
• Albian
• Peñacerrada I
• El Soplao

Acknowledgements

We thank the director and curators of the Museo de Ciencias Naturales de Álava and the staff from Cueva El Soplao for the loan of the Spanish amber specimens described herein. The authors are grateful to Rafael López del Valle for the preparation of the specimens and Dr Vincent Perrichot (Rennes University) for the loan of French specimens. Thanks are also given to Dr Eduardo Barrón (IGME) for identifying pollen grains and Dr Antonio Arillo (Complutense University) for helping us with Diptera and Acari identifications. We thank two anonymous reviewers for their useful comments and edits. Consuelo Sendino (NHMUK) is acknowledged for her work on the figure quality. This study is part of the PhD dissertation of the first author, which is supported by a grant from the Spanish Ministry of Economy and Competitiveness. RPF is funded through the NSF grant 1305066. This study is a contribution to the project of the Spanish Ministry mentioned above [CGL2011-23948/BTE]: ‘The Cretaceous amber of Spain: a pluridisciplinary study’.