The Pitcairn angelfish like the other angelfishes in the genus '' Genicanthus'', shows
sexual dichromatism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
, the males and females show differences in colour and pattern. The males have a white body which is marked with many vertical black stripes while the females have an overall bluish white colouration. In both sexes the forked tail narrows at its base to create a “swallow tail”. The dorsal fin contains 15 spines and 17 soft rays while the anal fin has 3 spines and 18-19 soft rays. This species attains a maximum total length of .
Distribution
''Genicanthus spinus'' is found in the southwestern Pacific Ocean. It has been recorded from the islands of Raivavae and
Rurutu
Rūrutu is the northernmost island in the Austral archipelago of French Polynesia, and the name of a commune consisting solely of that island. It is situated south of Tahiti. Its land area is .Austral Islands of
French Polynesia
)Territorial motto: ( en, "Great Tahiti of the Golden Haze")
, anthem =
, song_type = Regional anthem
, song = " Ia Ora 'O Tahiti Nui"
, image_map = French Polynesia on the globe (French Polynesia centered).svg
, map_alt = Location of Frenc ...
Dulcie Atoll in the
UK Overseas Territory
The British Overseas Territories (BOTs), also known as the United Kingdom Overseas Territories (UKOTs), are fourteen territories with a constitutional and historical link with the United Kingdom. They are the last remnants of the former Bri ...
of the
Pitcairn Islands
The Pitcairn Islands (; Pitkern: '), officially the Pitcairn, Henderson, Ducie and Oeno Islands, is a group of four volcanic islands in the southern Pacific Ocean that form the sole British Overseas Territory in the Pacific Ocean. The four isl ...
and
Rarotonga
Rarotonga is the largest and most populous of the Cook Islands. The island is volcanic, with an area of , and is home to almost 75% of the country's population, with 13,007 of a total population of 17,434. The Cook Islands' Parliament buildings a ...
''Genicanthus spinus'' Is found on rock and coral reefs at depths between (at least). it is normally encountered in groups that swim high in the water column, these are harems of 1 male and as many as 4 females. They feed mostly on zooplankton but may eat some benthic invertebrates.
Systematics
''Genicanthus spinus'' was first formally described in 1975 by the American
ichthyologist
Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 33,400 species of fish had been described as of Octobe ...
s John E. Randall (1924–2020) with the type locality given as
Bounty Bay
Bounty Bay is an embayment of the Pacific Ocean into Pitcairn Island. It is named after the HMS Bounty, ''Bounty'', a United Kingdom, British naval vessel whose eighteenth-century Mutiny on the Bounty, mutiny was immortalized in the novel ''Mutiny ...
on
Pitcairn Island
Pitcairn Island is the only inhabited island of the Pitcairn Islands, of which many inhabitants are descendants of mutineers of HMS ''Bounty''.
Geography
The island is of volcanic origin, with a rugged cliff coastline. Unlike many other ...
. The specific name ''spinus'' means “spine” and refers to the very large anterior spine in front of the eye.