St. Paul's fingerfin (''Nemadactylus monodactylus''), is a species 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 h ...

, traditionally regarded as belonging to the

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

Cheilodactylidae, the members of which are commonly known as morwongs. It is native to the southwestern Indian Ocean and southeastern Atlantic Ocean.

Taxonomy

The St. Paul’s fingerfin was first formally described as ''Chaetodon monodactylus'' in 1819 by the Scottish Army surgeon and botanist

Dugald Carmichael Dugald Carmichael (born 1772 in Stronacraoibh, Lismore Island, died 1827 in Appin) was a Scottish botanist and officer in the 72nd Highlanders. He is known as the "Father of Marine Botany Marine botany is the study of flowering vascular plant s ...

with the

type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

given as

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 Helen ...

. The specific name ''monodactylus'' means “one fingered”, a reference to the elongated 6th lowest fin ray in the

pectoral 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 ...

. Genetic and morphological analyses strongly support the placement of ''Nemadactylus'' in the family

Latridae Latridae commonly called trumpeters, is a family of marine ray-finned fish. They are found in temperate seas in the Southern Hemisphere. The classification of the species within the Latridae and the related Cheilodactylidae is unclear.They are ...

, alongside almost all of the other species formerly classified in the Cheilodactylidae.

Description

St Paul’s fingerfin has an oblong and compressed body, its shape altering as the fish grows. it has small head with a small mouth with thick, fleshy lips and small villiform teeth arranged in rows in the front of the jaws. They have a long

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 c ...

which contains 17 or 18 spines and 24 to 27 soft rays while 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 s ...

with 3 robust spines, the middle one being the most robust, and 12 soft rays. The

s have 15 or 16 rays, of which the lowest 6 or 7 are robust, simple and extended, one of the two uppermost rays are very robust and longer than the others, reaching the anal fin spine. The

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two e ...

s are located quite far to the rear of the pectoral fins. The caudal fin is forked. The overall colour is grey with darker vertical bars which disappear in air. The maximum total length of this species .

Distribution and habitat

The St Paul’s fingerfin occurs around the Tristan Islands and the

Vema Seamount Vema Seamount is a seamount in the South Atlantic Ocean. Discovered in 1959 by a ship with the same name, it lies from Tristan da Cunha and northwest of Cape Town. The seamount has a flat top at a mean depth of which was eroded into the seamoun ...

in the South Atlantic Ocean and off

Amsterdam Amsterdam ( , , , lit. ''The Dam on the River Amstel'') is the Capital of the Netherlands, capital and Municipalities of the Netherlands, most populous city of the Netherlands, with The Hague being the seat of government. It has a population ...

and St Paul Island in the southwestern Indian Ocean and on the

Austral Seamount Austral means 'southern', often in reference to the Southern Hemisphere. Austral may also refer to: Businesses *Austral Líneas Aéreas, an Argentine airline * Air Austral, an airline based in Réunion *Austral (bus manufacturer), a defunct Aus ...

and

Walters Shoal The Walters Shoals is a group of submerged mountains off the coast of Madagascar. The shoals are south of Cape Sainte Marie - Madagascar and east of Richards Bay at the African coast. The tips of some of the mountains are only below the s ...

. It is the commonest fish off Tristan da Cunha. This is a

benthopelagic 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 o ...

species.

Biology

The St Paul’s fingerfin is a carnivorous species which feeds on

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

and

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

animals.

Fisheries

The St Paul’s fingerfin is fished for but no statistics are complied on the landings. There is a minimum size limit of on catches in Tristan da Cunha.

References

* * {{Taxonbar, from=Q2197445 St. Paul's fingerfin Fish described in 1819