Middle-American Poeciliid Fishes of the Genus Xiphophorus

Abstract

Drawing upon information from the present studies of the comparative and functional morphology, distribution, and ecology of the forms of Xiphophorus (Cyprinodontiformes: Poeciliidae) and those made during the last quarter of a century on their genetics, cytology, embryology, endocrinology, and ethology, the species are classified and arranged to indicate their probable phylogenetic relationships. Their evolution and zoogeography are considered in relation to a proposed center of adaptive radiation on Mexico's Atlantic coastal plain. Five new forms are described: X. variatus evelynae, new subspecies; X. milleri, new species; X. montezumae cortezi, new subspecies; X. pygmaeus nigrensis, new subspecies; X. helleri alvarezi, new subspecies.