Morphometrics of echinoids in the Family Cassidulidae (Echinoidea: Cassiduloida).

Cassidulidae is the type family of the order Cassiduloida, and contains five genera whose morphology has complicated their taxonomic study: Australanthus, Cassidulus, Eurhodia, Paralampas, and Rhyncholampas. Many authors have applied traditional morphometric analysis (mainly length, width, and height) with varying success. We present the first approach with geometric morphometrics (three outlines: aboral, left, and posterior). Genera Eurhodia and Paralampas are more varied than the others. For future studies, we recommend larger samples, and the inclusion of size and qualitative characters such as the ambulacra and peristome. Rev. Biol. Trop. 65(Suppl. 1): S233-S243. Epub 2017 November 01.

Keywords: Geometric Morphometrics, Taxonomy, Coordinates Geometry, Principal Component Analysis.