Xiphophorus milleri
Xiphophorus milleri, the Catemaco platyfish, is a poeciliid fish endemic to Mexico's Lake Catemaco and its tributaries. As it has traits of both swordtails and platies, its discovery confirmed that these two groups should be consolidated into a single genus, Xiphophorus.
Taxonomy
The species was named after American ichthyologist Robert Rush Miller, who collected it along with other Xiphophorus species. Its discovery enabled scientists to definitely conclude that platies and swordtails should be classified in the same genus, for it combines traits that were thought to separate platies from swordtails into different genera. Namely, X. milleri resembles the swordtails in body shape, pigmentation, and ecology, but shares the platies' secondary sexual characteristics, pigmentary polymorphism, and the absence of a sword.Description
Xiphophorus milleri is a small to medium Xiphophorus species. Its body is slender. Nearly a half of specimens have melanophore markings of varying sizes. These are arranged in one of two types of patterns: irregular dark spots on the body; and definite rows of spots on the side. Three tail patterns exist: one with a single small spot, one with a single large spot, and a bar-like pattern. Adult males have deep yellow-orange bellies.Females grow to total length, while males attain. The males are elongated, while the females appear humpbacked and compact.