A phylogenetic analysis of selected anomuran, thalassinidean, and other decapod crustacean taxa, based on spermatozoal ultrastructural characters and spermatophore morphological characters, was performed and the following relationships of the taxa are elucidated from the trees produced. The Anomura are not a monophyletic assemblage, with the lomoid Lomis being exclusive of the remainder of the anomuran taxa, and the thalassinid Thalassina included in the anomuran clade. The synapomorphy joining the majority of the conventional anomuran taxa (Lomis excluded) is the cytoplasmic origin of the microtubular arms. When the palinurid and thalassinoid representatives are separately designated as outgroups, the Astacidea and Brachyura jointly formed a sister group to the Anomura. The superfamilies Thalassinoidea, Paguroidea, and Galatheoidea are not monophyletic groups. In all analyses the anomuran families Coenobitidae and Porcellanidae each form a monophyletic group. The paguroid family Diogenidae is paraphyletic, with the genera Clibanarius and Cancellus separate from a single clade containing the remaining diogenid genera. The families Paguridae and Parapaguridae form a monophyletic clade with the exception of Porcellanopagurus. The two representatives of the family Chirostylidae (Eumunida and Uroptychus) fail to associate with the other species in the Galatheoidea. The taxa in the family Galatheidae are not a monophyletic assemblage. The only investigated hippoid Hippa is portrayed as the sister group to the remainder of the anomuran taxa (with the exception of Lomis).