The enigmatic Cyclida (Pancrustacea): morphological terminology and family-level classification

Abstract

Abstract The Cyclida comprise six families embracing 55 species in 17 genera. Diagnoses for each family based upon examination of type and referred material as well as photographs of specimens previously known only from drawings has confirmed that four of the families, Cyclidae Packard, 1885; Americlidae Dzik, 2008; Halicynidae Gall & Grauvogel, 1967; and Schraminidae Dzik, 2008, form a unified group morphologically whereas Alsasuacaridae van Bakel, Jagt, Fraaije & Artal, 2011, and Hemitrochiscidae Trauth, 1918 are morphological outliers. Each of the families is documented by illustrations of type or representative genera and species. To assure accurate and uniform comparisons of taxa, a morphological terminology is presented, recognizing synonymous terms that could potentially obscure evaluation of relationships. This provides a framework for future analysis of membership within each family and for phylogenetic analyses.