Prognathodes dichrous

Lore & Background

Prognathodes dichrous was first formally described in 1869 by the German-born British zoologist Albert Günther, with the type locality given as St Helena. Its closest relative appears to be the rather similar Prognathodes obliquus, which is endemic to St Paul Rocks off Brazil. The species is largely brown in color, with the upper rear quarter of the body white, including the dorsal and caudal fins. It also has a white eye ring. The dorsal fin contains 12 spines and 19 soft rays, while the anal fin has 3 spines and 15 soft rays. This species attains a maximum total length of 16 centimeters.

Reader's Guide

Prognathodes dichrous is a species of deeper water, normally found between 12 and 35 meters, though at Hummock Point it can be seen in water as shallow as 1 meter. It inhabits caves, under overhangs, and on seamounts. Typically encountered in pairs, shoals have also been recorded. It browses on benthic invertebrates over rocky areas. This is an oviparous species that spawns as pairs. Its restricted range to the British Overseas Territories of Ascension and Saint Helena islands makes it a notable endemic of the southeastern Atlantic Ocean. The species' closest relative, Prognathodes obliquus, is found only at St Paul Rocks off Brazil, highlighting a biogeographic connection between these isolated Atlantic locations.

Did You Know?

• Prognathodes dichrous is also known as the bastard cunningfish or hedgehog butterflyfish.
• It has a white eye ring and a white upper rear quarter of the body including the dorsal and caudal fins.
• It is normally found between 12 and 35 meters deep, but at Hummock Point it can be seen as shallow as 1 meter.