''Pentaceros richardsoni'', the pelagic armourhead, Richardson's boarfish or southern boarfish, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

, an

armourhead Pentacerotidae or armourheads are a small family of fishes in the order Perciformes. They are native to the Indian Ocean, western and central Pacific, and southwestern Atlantic. They are generally found at rocky reefs below normal scuba diving d ...

from the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Pentacerotidae Pentacerotidae or armourheads are a small family of fishes in the order Perciformes. They are native to the Indian Ocean, western and central Pacific, and southwestern Atlantic. They are generally found at rocky reefs below normal scuba diving d ...

. It has a wide distribution in the oceans of the southern hemisphere. It is

commercially Commerce is the large-scale organized system of activities, functions, procedures and institutions directly and indirectly related to the exchange (buying and selling) of goods and services among two or more parties within local, regional, nation ...

important as a food fish.

Description

''Pentaceros richardsoni'' is a large armourhead with quite a large head and a moderately deep body which is laterally compressed and slightly rounded. The head is largely covered in finely marked bones which are rough to the touch. It has a straight snout which becomes rounded and bulbous in mature adults. The small mouth is slightly angled upwards and has jaws armed with narrow bands of short, moderately curved teeth and there are teeth on the roof of the mouth. The body is covered on small, ctenoid rough scales which form small polygonal plates which interlock on the throat and abdomen. The

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

is high up on the flanks and its for parallels the dorsal profile. The

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

contains 14–15 spines and 8–9 soft rays and is continuous and long based. The spines at the head end increases in length and thickness with the fourth spine being the longest and most robust, the spines the decrease in length and thickness. The soft rays are taller than the ultimate dorsal spines. The

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

has a short base, sits opposite the soft part of the dorsal fin and is similar in form to it, it has 4–5 spines and 8–9 soft rays. The

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

is a little bit emarginate. The colouration of this species is that it is iridescent dark blue dorsally and silvery-grey on the flanks and the underside. This species attains a maximum

total length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

of .

Distribution

''Pentaceros richardsoni'' is a species which is found around the globe in the temperate waters of the Oceans of the Southern Hemisphere. It has been recorded from southern Australia, New Zealand and

Cape Horn Cape Horn ( es, Cabo de Hornos, ) is the southernmost headland of the Tierra del Fuego archipelago of southern Chile, and is located on the small Hornos Island. Although not the most southerly point of South America (which are the Diego Ramírez ...

in Chile in the Pacific, off eastern South Africa in the Indian Ocean and the

Western Cape The Western Cape is a province of South Africa, situated on the south-western coast of the country. It is the fourth largest of the nine provinces with an area of , and the third most populous, with an estimated 7 million inhabitants in 2020 ...

and

Tristan da Cunha Tristan da Cunha (), colloquially Tristan, is a remote group of volcanic islands in the South Atlantic Ocean. It is the most remote inhabited archipelago in the world, lying approximately from Cape Town in South Africa, from Saint Helena ...

in the Atlantic Ocean. Records from the North Pacific refer to another species.

Habitat and biology

''Pentaceros richardsoni'' is a

demersal The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...

species as an adult The adults can be found at depth while juveniles are found nearer the surface. They are frequently found in the vicinity of seamounts, ridges and rises. It has been found down to depths of .

Taxonomy

''Pentaceros richardsoni'' was first formally described in 1844 by the Scots

surgeon In modern medicine, a surgeon is a medical professional who performs surgery. Although there are different traditions in different times and places, a modern surgeon usually is also a licensed physician or received the same medical training as ...

, explorer,

ethnologist Ethnology (from the grc-gre, ἔθνος, meaning 'nation') is an academic field that compares and analyzes the characteristics of different peoples and the relationships between them (compare cultural, social, or sociocultural anthropology) ...

and

zoologist Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological clas ...

Andrew Smith (1797–1872) with the type locality given as

Cape Point Cape Point ( af, Kaappunt) is a promontory at the southeast corner of the Cape Peninsula, a mountainous and scenic landform that runs north-south for about thirty kilometres at the extreme southwestern tip of the African continent in South Afri ...

, South Africa. For a long time it was placed in the genus ''Pseudopentaceros'' but examination of

skeletal A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...

and musculature has led to ''Pseudopentaceros'' being considered a

junior synonym The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...

of ''

Pentaceros ''Pentaceros'' is a genus of marine ray-finned fish, armorheads from the family Pentacerotidae. They are native to the Pacific, Indian, and eastern Atlantic Oceans. ''Pentaceros'' is the only genus in the monotypic subfamily Pentacerotinae. Spe ...

''. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

honours the naval surgeon, naturalist and

arctic The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...

explorer Sir John Richardson.

References

{{Taxonbar, from=Q2791028 richardsoni Fish of the Atlantic Ocean Fish of the Indian Ocean Fish of the Pacific Ocean Fish described in 1844 Taxa named by Andrew Smith (zoologist)