Evolution and systematics

The suborder Percoidei contains more than 70 families and 2,800 species. This section on the Percoidei deals with 18 families of fishes. The families are the Mullidae (goatfishes), Tox-otidae (archerfishes), Dichistiidae (galjoens), Kyphosidae (sea chubs or rudderfishes), Paracorpididae (jutjaws), Drepaneidae (sicklefishes), Monodactylidae (monos or moonfishes), Chaetodontidae (butterflyfishes), Pomacanthidae (angelfishes), Enoplosidae (oldwives), Pentacerotidae (armorheads and boarfishes), Nandidae (leaffishes), Oplegnathidae (knifejaws), Cirrhitidae (hawkfishes), Chironemidae (kelpfishes), Aplo-dactylidae (seacarps or marblefishes), Cheilodactylidae (mor-wongs), and Latridae (trumpeters).

Fossil records indicate that perciform fishes date back as far as the Cenozoic era (about 65 million years ago), with per-coids evolving rapidly during the Eocene epoch. This rapid evolution is evident in such families as the Chaetodontidae, Pomacanthidae, Mullidae, Kyphosidae, and Cirrhitidae, which contain the most species in the group. A number of families are placed in groups with variable degrees of formalization. For example, the Squammipinnes is an unranked group, denoted by having rows of scales covering the base of the dorsal and anal fins, and includes the Monodactylidae, Toxotidae, Chaetodontidae, and Pomacanthidae. The Kyphosidae consists of four subfamilies, three of which were recognized previously as separate families. (A new molecular study of this polyphyletic group suggests that the subfamilies, which appear to be closely related to the Kuhlidae, might be recognized again as separate families.) The Nandidae also consists of three subfamilies recognized on the basis of their geographical distribution, which parallels the breakup of Gondwana (the supercontinent, made up of South America,

Africa, Antarctica, India, and Australia), thus making the nan-dids an ancient group. Leaffishes have been linked falsely with labyrinth fishes of the suborders Anabantoidei (gouramies and allies) and Channoidei (snakeheads). The superfamily Cirrhi-toidea is denoted by the presence of pectoral fins with five-to-eight unbranched and elongated lower fin rays on the pectoral fin. Members include the Cirrhitidae, Chironemidae, Aplodactylidae, Cheilodactylidae, and the Latridae.

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