Pelagic Armourhead, Pentaceros richardsoni (Smith 1844)

Other Names: Nelson's Boarfish, Richardson's Boarfish

A Pelagic Armourhead, Pentaceros richardsoni, from seamounts in the Tasman Sea. Source: Robin McPhee / NORFANZ Founding Parties. License: All rights reserved

A large dark iridescent steely blue boarfish becoming silvery-grey to greyish-green on the sides and below, with exposed finely sculptured head bones. Juveniles have the upper body variously marbled with pale lines, spots and blotches.
The Pelagic Armourhead was previously known as Pseudopentaceros richardsoni. Kim (2012) determined that Pseudopentaceros is a junior synonym of the genus Pentaceros.

Cite this page as:
Bray, D.J. 2018, Pentaceros richardsoni in Fishes of Australia, accessed 20 Jul 2024,

Pelagic Armourhead, Pentaceros richardsoni (Smith 1844)

More Info


From NE of Newcastle, New South Wales, southwards around Tasmania to SW of Beachport, South Australia, and west of Cape Leeuwin to W of Geraldton, Western Australia; also on the Norfolk Ridge in AUS EEZ. Elsewhere the species is circumglobal in temperate waters of the southern hemisphere - often around seamounts, ridges and rises.


Dorsal fin XIV-XV, 8-9; Anal fin IV-V, 7-8; Caudal fin 15-18; Pectoral fin 17-18; Pelvic fin I, 5; Lateral line 70-89.

Body moderately deep (38-45% SL), sides compressed, only slightly rounded; dorsal profile moderately rounded. Head of moderate size (29-36% SL), predominantly covered with rough, striated bones; snout straight but becoming anteriorly rounded and bulbous in large adults; eyes of moderate size; mouth small, slightly angled upwards; teeth of both jaws very short, slightly curved, set in narrow bands anteriorly, becoming more narrow along sides; vomer toothed. 
Scales small, ctenoid, rough and in form of small interlocking, polygonal plates on throat and belly, covering body and head; lateral line high on sides, following dorsal profile of body. 
Dorsal fin continuous with long base, spines increasing in length and strength to fourth spine and subsequently decreasing in stature; anterior soft dorsal rays slightly longer than posteriormost dorsal fin spine, edge of soft dorsal rounded; anal fin with short base, opposite and similar soft portion of dorsal fin; spine strong; caudal fin slightly emarginate. Pectoral fins moderately elongate, upper rays much longer than lower. Pelvic fins large, spine strong.


Steel blue to greyish-green, lower surface paler; pectoral and caudal fins dark, pelvic fins pale. Upper body in juveniles variously marbled with pale lines and spots.


The Pelagic Armourhead was, until recently called Pseudopentaceros richardsoni. Kim (2012) in a study examining osteological and myological (muscle) characters, concluded that the genus Pseudopentaceros is a junior synonym of Pentaceros.

Species Citation

Pentaceros richardsoni Smith, 1844, Illustr. Zool. Sth. Africa: unnumbered, pl. 21. Type locality: near Cape Point, South Africa.


Bray, D.J. 2018


Australian Faunal Directory

Pelagic Armourhead, Pentaceros richardsoni (Smith 1844)


Andrew, T.G., Hecht, T., Heemstra, P.C. & Lutjeharms, J.R.E. 1995. Fishes of the Tristan da Cunha group and Gough Island, south Atlantic Ocean. Ichthyological Bulletin of the J.L.B. Smith Institute, Grahamstown 63: 1-43 figs 1-34 pls 1-2 (as Pseudopentaceros richardsoni)

Gomon, M.F. 2008. Families Enoplosidae and Pentacerotidae. pp. 609-617 in Gomon, M.F., Bray, D.J. & Kuiter, R.H. (eds). Fishes of Australia's Southern Coast. Sydney : Reed New Holland 928 pp. (as Pseudopentaceros richardsoni)

Hardy, G.S. 1983. A revision of the fishes of the family Pentacerotidae (Perciformes). New Zealand Journal of Zoology 10: 177-220 figs 1-13 (as Pseudopentaceros richardsoni)

Hardy, G.S. 1994. Family Pentacerotidae. pp. 629-636, figs 553-559 in Gomon, M.F., Glover, C.J.M. & Kuiter, R.H. (eds). The Fishes of Australia's South Coast. Adelaide : State Printer 992 pp. 810 figs. (as Pseudopentaceros richardsoni)

Kim, S.-Y. 2012. Phylogenetic systematics of the family Pentacerotidae (Actinopterygii: Order Perciformes). Zootaxa 3366: 1-111. PDF Open access
May, J.L. & Maxwell, J.G.H. 1986. Field Guide to Trawl Fish from Temperate Waters of Australia. Hobart : CSIRO Division of Marine Research 492 pp. (as Pseudopentaceros richardsoni)

Paulin, C., Stewart, A., Roberts, C. & McMillan, P. 1989. New Zealand fish: a complete guide. National Museum of New Zealand Miscellaneous Series 19: 1-279. (as Pseudopentaceros richardsoni)

Smith, A. 1844. Illustrations of the Zoology of South Africa; consisting chiefly of figures and descriptions of the objects of natural history collected during an expedition into the interior of South Africa, in the years 1834, 1835 and 1836. Pisces. London : Smith, Elder & Co. Vol. 4 83 pp. 31 pls.

Quick Facts

CAAB Code:37367009

Depth:50-750 m


Max Size:56 cm TL

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