Acanthostracion

Lore & Background

Acanthostracion was first proposed as a subgenus of Ostracion in 1865 by the Dutch physician, herpetologist and ichthyologist Pieter Bleeker. Bleeker did not designate a type species when he first used the name in his paper Notice sur les ostracions, confondus sous le nom d'Ostracion quadricornis L. et description des Ostracion notacanthus et guineensis, but designated Ostracion quadricornis as the type species later in 1865 when he published his Atlas ichthyologique des Indes Orientalis Neerlandais. The 5th edition of Fishes of the World classifies this genus within the family Ostraciidae in the suborder Ostracioidea within the order Tetraodontiformes.

The etymology of Acanthostracion comes from ἄκανθα (ákantha), meaning 'spine, thorn', and Ostracion, as Bleeker originally proposed this taxon as a subgenus of the latter genus. There are currently four recognized species: Acanthostracion guineense (West African cowfish), Acanthostracion notacanthus (Island cowfish), Acanthostracion polygonius (Honeycomb cowfish), and Acanthostracion quadricornis (Scrawled cowfish).

Acanthostracion cowfishes have an oblong, broad body encased within a bony carapace made up of thickened, typically hexagonal plate-like scales which are sutured together. This carapace does not enclose the mouth, eyes, gill slits, fins and the caudal peduncle and caudal fin, although it does encircle the bases of the dorsal and anal fins. There are large spines which project in front of the eyes, as well as spines at the lower rear angle of the carapace, and the rearmost plate-like scales on the upper and lower caudal peduncle are expanded into small spines. The small mouth sits at the front of the snout and has fleshy lips and around 15 moderately sized conical teeth in each jaw. These cowfishes have maximum published total lengths from 18 cm in the West African cowfish to 55 cm in the scrawled cowfish.

Reader's Guide

Acanthostracion is significant as a genus of boxfishes restricted to the Atlantic Ocean, with two Western Atlantic species distributed from New Jersey to Brazil and two Eastern Atlantic species off West Africa, as well as the Azores, Saint Helena, and Ascension Island. The genus was first proposed as a subgenus by Pieter Bleeker in 1865, and its type species was designated later that same year. The name reflects the spiny nature of these fishes, combining Greek for 'spine' with the genus Ostracion. The four recognized species vary in size from 18 cm to 55 cm in total length. The bony carapace and spines, including those in front of the eyes and at the rear of the carapace, are characteristic features. The carapace does not enclose the mouth, eyes, gill slits, fins, or caudal peduncle, but does encircle the bases of the dorsal and anal fins. The mouth has fleshy lips and about 15 conical teeth per jaw. These details, along with the geographic distribution, define the genus's legacy in the family Ostraciidae.

Did You Know?

• The genus name comes from Greek words meaning 'spine' and 'Ostracion'.
• There are four recognized species, with maximum lengths ranging from 18 cm to 55 cm.
• These cowfishes are found only in the Atlantic Ocean, from New Jersey to Brazil and off West Africa.