In the debate over phylogenetic relationships within the Decapoda that has raged for more than a century, the Anomura has been the source of many “confl icts”, including disagreements over which taxa belong in this morphologically diverse infraorder, and even what name is appropriate (Anomura or Anomala). The Anomura currently includes 17 families, 222 genera, and about 2,469 species, although 54% of the genera and 43% of the species are paguroids. A number of studies have summarized the traditional as well as recent concepts of the infraorder that were based on morphology. This review addresses modern studies on systematics of this group over the last two decades that have been based on molecular as well as morphological data, and which have continued to add controversy to concepts of anomuran phylogeny. The landmark study by C.W. Cunningham and co-workers (published in ‘Nature’ in 1992), proclaiming that molecular data confi rmed the traditional hypothesis on the evolution of king crabs from hermit crabs, was the catalyst for several studies on anomuran evolution that followed, and is the starting point of this review. Modern studies are divided as follows, and discussed: 1) morphological, larval and molecular phylogenies exclusively of the Paguroidea and/or Anomura; 2) spermatologically derived phylogenies; 3) information from the fossil record; 4) phylogenetic assessments of anomuran taxa included in general decapod analyses; and 5) auxiliary information pertaining to the Paguroidea in general, and Pylochelidae in particular. These studies have made useful contributions to understanding the “big picture” of anomuran relationships but they also have limitations. It is concluded that the Anomura remains today as much a source of discord as it was a century ago, and “confl icts” in analyses will continue to cloud the landscape until more basic, complete information is gathered for all members of this intriguing and varied infraorder.

Anomura, phylogenetic relationships, modern concepts, confl icts, review