Prionurus

Prionurus is a genus of marine ray-finned fishes belonging to the family Acanthuridae, the surgeonfishes, unicornfishes and tangs, although some of the species in this genus are called sawtails or doctorfish. The species in this genus are found in the Pacific Ocean with one species, P. biafraensis, found in the Atlantic Ocean.

Taxonomy
Prionurus was first proposed as a monospecific genus in 1804 by the French naturalist Bernard Germain de Lacépède when he described Prionurus microlepidotus. Lacépède did not give a type locality but the type was collected by François Péron off New South Wales. The genus Prionurus is the only genus in the tribe Prionurini which is one of three tribes in the subfamily Acanthurinae which is one of two subfamiles in the family Acanthuridae.

Etymology
Prionurus means "sawtail" a reference to the 3 to 7 immobile keeled bony plates on each side of the caudal peduncle.

Species
There are currently seven recognized species in this genus:
 * Prionurus biafraensis (Blache & Rossignol, 1961) - Biafra doctorfish
 * Prionurus chrysurus J. E. Randall, 2001
 * Prionurus laticlavius (Valenciennes, 1846) - razor surgeonfish
 * Prionurus maculatus J. D. Ogilby, 1887 - yellowspotted sawtail
 * Prionurus microlepidotus Lacépède, 1804 - sixplate sawtail
 * Prionurus punctatus T. N. Gill, 1862 - yellowtail surgeonfish
 * Prionurus scalprum Valenciennes, 1835 - scalpel sawtail

Characteristics
Prionurus species have oval, compressed bodies with a steep angle on the head above the snout. The small mouth is protrusible and is positioned low on the head. The teeth are set closely together and are moderately large, flattened and have serrated edges. They have 8 or 9 spines in the dorsal fin and 3 spines in the anal fin. The caudal peduncle has between 3 and 7 bony plates with sharp keels on each side. The spined keels in the caudal peduncle are immobile in this genus compared to mobile ones in other surgeonfishes. These fishes vary in their maximum published total lengths from 20 cm in P. biafraensis to 70 cm in P. microlepidotus.

Distribution
Prionurus have a predominantly Pacific range with six of the seven species being found in the Pacific Ocean, two of these, P. laticlavus and P. punctatus being endemic to the eastern Pacific and one, P. biafraensis, being endemic to the Eastern Atlantic.