Relationships of Atherinomorph Fishes (Teleostei)

Abstract

Atherinomorphs have been recognized since 1964 as a group of teleost fishes comprising silversides, phallostethids, killifishes, ricefishes, halfbeaks, needlefishes, flying fishes, and sauries. Atherinomorphs are diagnosed as monophyletic by derived characters of the testis, egg, reproductive behavior, circulatory system, ethmoid region of the skull, gill arches, pelvic girdle, jaw musculature, olfactory organ, and inferred reductions in the infraorbital series and some other bones. Monophyly of killifishes (Cyprinodontiformes), ricefishes and exocoetoids (Beloniformes), and Division II atherinomorphs (Cyprinodontiformes plus Beloniformes) is well-supported. Atherinoids (silversides plus phallostethids) are considered paraphyletic. One cladistic interpretation of character distribution among selected ctenosquamate teleosts supports the hypothesis that atherinomorphs are the sister group of some or all paracanthopterygian fishes. However, corroboration of an atherinomorph sister group, and modification of atherinomorph membership, requires more precise definition of derived characters (i.e., better statement of homology) and continued surveys of characters, such as testis structure, in outgroup taxa.