Osteology and Systematic Position of the Butterfly Mackerel, Gasterochisma melampus

Abstract

A detailed description of the osteology of Gasterochisma melampus is presented, and the systematic position of the species is discussed through comparison with other perciform species from nine families.Of the 13 osteological characters considered in this study to be diagnostic of the Scombridae, 12 are shared by G.melampus.On the other hand, in perciform families other than the Scombridae, there are no characters of a particular family shared only by G.melampus, except for the ethmoid of the Coryphaenidae.In addition to the above scombrid characters, G.melampus possesses 15 characters which are seen in none of the other species, and these characters are mostly seen in the neurocranium.The osteological characters of G.melampus represent both primitive and advanced states in the Scombridae.On the basis of these osteological observations, G.melampus can be considered to have been derived from the scombrid stem at an early time and to have undergone its own specialization.G.melampus is regarded as an aberrant form but still within the taxonomic limits of the family Scombridae.