An array of sixth abdominal tergite types of paguroid anomurans (Crustacea) from the mid-Cretaceous of Navarra, northern Spain

Abstract

In recent years, a range of operculate sixth abdominal tergite types of pylochelid and parapylochelid hermit crabs (Anomura, Paguroidea) have been recorded from Upper Jurassic (Oxfordian and Kimmeridgian) strata in southern Poland and southern Germany. Here we add two new genera (Parapylochelitergites, Paguritergites) and four new late Early Cretaceous species (Parapylochelitergites pustulosus, Pylochelitergites alatus, Pylochelitergites rugosus and Paguritergites yvonnecooleae) from Navarra, northern Spain. In the reefal limestones at Koskobilo quarry near Alsasua, of late Albian age, the number of sixth abdominal paguroid tergite taxa approximates that of paguroid carapace types. Thus, linking fossil paguroid carapaces to tergites can now be attempted. Assemblages of symmetrical hermit crabs (parapylochelids and pylochelids) in reefal settings appear to have changed drastically from the late Albian onwards, with asymmetrical forms (Diogenidae, Paguridae) becoming predominant.