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

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

, traditionally regarded as belonging to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Cheilodactylidae Cheilodactylidae, commonly called morwongs but also known as butterfish, fingerfins, jackassfish, sea carp, snappers, and moki, is a family of marine ray-finned fish. They are found in subtropical oceans in the Southern Hemisphere. The common na ...

, 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 Scottish usually refers to something of, from, or related to Scotland, including: *Scottish Gaelic, a Celtic Goidelic language of the Indo-European language family native to Scotland *Scottish English *Scottish national identity, the Scottish ide ...

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and

botanist Botany, also called plant science, is the branch of natural science and biology studying plants, especially Plant anatomy, their anatomy, Plant taxonomy, taxonomy, and Plant ecology, ecology. A botanist or plant scientist is a scientist who s ...

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". The plant genus ''Carmichaelia'' is named after him. H ...

with the type locality given as

Tristan da Cunha Tristan da Cunha (), colloquially Tristan, is a remote group of volcano, volcanic islands in the South Atlantic Ocean. It is one of three constituent parts of the British Overseas Territories, British Overseas Territory of Saint Helena, Ascensi ...

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

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

. 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 on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

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

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

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 (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

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 seamou ...

in the South Atlantic Ocean and off

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and St Paul Island in the southwestern Indian Ocean and on the Austral Seamount and Walters Shoal. 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 of ...

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 the Ancient Greek word (), meaning "the depths". ...

and

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

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 Taxa named by Dugald Carmichael Fish described in 1819