With the objective of testing the monophyly of the Calyptraeoidea and of searching for its ground plan, a detailed morpho-logical analysis was conducted for the following species: a) Family Calyptraeidae, 1) Bostrycapulus aculeatus (Gmelin) (formerly Crepidula); 2) Crepidula aff. plana Say; 3) C. protea Orbigny (these from Brazil); 4) C. aff. protea (from Argentina) (published elsewhere); 5) C. convexa Say (from Venezuela); 6) C. fornicata (L.) (from Europe); 7) Calyptraea centralis (Conrad) (from Brazil); 8) Crucibulum auricula (Gmelin) (from Venezuela); 9) Cr. quiriquinae (Lesson) (from Chile); 10) Trochita trochiformis (Born) (from Chile); 11) Sigapatella calyptraeformis (Lam.) (from New Zealand, formerly Calyptraea); b) Family Hipponicidae, 12) Hipponix costellatus Carpenter (formerly H. grayanus); 13) H. subrufus (Lam.); 14) H. incurvus (Gmelin) (formerly Capulus incurvatus) (these 3 from NE Brazil); 15) H. grayanus Menke (from Mexico and Ecuador); 16) H. leptus n. sp. (N.E. Brazil); 17) Sabia conica (Schumacher); 18) Malluvium devotus (Hedley) (both Australia); 19) Cheilea equestris (L.) (N.E. Brazil); c) Family Capulidae, 20) Capulus sycophanta Garrard (Australia); d) Family Trichotropidae, 21) Trichotropis cancellata Hinds (W. USA); 22) T. borealis Broderip & Sowerby (N. Atlantic); 23) T. sp. (Alaska); e) Family Vanikoridae, 24) Vanikoro sp. (Australia). A phylogenetic analysis of 112 characters (177 states) from morphology of all systems and organs results in the following single most parsimonious tree: ((Trichotropis cancellata - T. borealis) (Capulus sycophanta (Vanikoro sp ((Cheilea equestris (Sabia conica (Malluvium devotus ((Hipponix grayanus - H. leptus) (H. incurvus (H. costellatus - H. subrufus)))))) (Sigapatella calyptraeformis (Trochita trochiformis (Calyptraea centralis ((Crucibulum auricula - Cr. quiriquinae) (Bostrycapulus aculeatus (Crepidula argentina (C. convexa (C. fornicata (C. aff. plana - C. protea))))))))))))). Length: 267, CI: 67, RI: 88. Outgroups from other caenogastropod superfamilies were used as well as some archaeogastropod groups. The main result is the monophyly of Calyptraeoidea supported by 27 synapomorphies with basal Caenogastropoda used as the outgroup (Cerithioidea, Hydrobioidea), and 21 synapomorphies when Stromboidea and Cypraeoidea were used as outgroups. Calyptraeoidea includes, succes-sively along the tree, the following monophyletic families: Trichotropidae, Capulidae, Vanikoridae, Hipponicidae and Calyptraeidae. The hipponicid affinity of Cheilea is confirmed. Some taxonomic problems found in the sampled representatives (as mentioned above), were partially resolved.
Caenogastropoda; Calyptraeoidea phylogeny; morphology; cladistic analysis; Hipponicoidea; Capuloidea