Scombroid phylogeny: an alternative hypothesis

A new hypothesis of the cladistic intrarelationships of the perciform suborder Scombroidei and immediate outgroups is proposed, based on 49 characters, most of them osteological. This hypothesis differs from the one proposed recently by Collette et al. (1984) in several respects. An hypothesis of precise outgroup relationships is presented. Outgroup taxa are, in phyletic sequence: Dinolestes plus several genera previously placed in the Acropomatidae; Scombrops; Scombrolabrax; and Pomatomus (first outgroup). Sphyraena is included in the Scombroidei as the sister group of all other scombroids. The Gempylidae, rediagnosed, is the sister group of the scombrids plus billfishes; within the Gempylidae, Lepidocybium is the sister group of the Gempylinae plus Trichiurinae. The billfishes (Istiophoridae plus Xiphias) are the sister group of Acanthocybium and, in a cladistic classification, must be treated as a subgroup of the Scombridae. The precise affinities of Gasterochisma remain unresolved; data on larval morphology and developmental osteology, currently unavailable, should help resolve the placement of this enigmatic genus, which exhibits a perplexing combination of primitive and derived character states.