''Gymnocrotaphus'' is a ''monospecific genus'' 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 ...

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 ...

Sparidae Sparidae is a family of ray-finned fishes belonging to the order Spariformes, the seabreams and porgies, although they were traditionally classified in the order Perciformes. The over 150 species are found in shallow and deep marine waters in t ...

, which includes the seabreams and porgies. The only species in the genus is the ''Gymnocrotophus curvidens'', the Janbruin, an

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the coasts of South Africa.

Taxonomy

''Gymnocrotaphus'' was first proposed as a monospecific genus in 1859 by the German-bprn British

herpetologist Herpetology (from Ancient Greek ἑρπετόν ''herpetón'', meaning "reptile" or "creeping animal") is a branch of zoology concerned with the study of amphibians (including frogs, salamanders, and caecilians (Gymnophiona)) and reptiles (in ...

and

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, 35,800 species of fish had been described as of March 2 ...

Albert Günther Albert Karl Ludwig Gotthilf Günther , also Albert Charles Lewis Gotthilf Günther (3October 18301February 1914), was a German-born British zoologist, ichthyologist, and herpetologist. Günther is ranked the second-most productive reptile tax ...

when he described its only species, ''Gymnocrotaphus curvidens'', from the

Cape of Good Hope The Cape of Good Hope ( ) is a rocky headland on the Atlantic Ocean, Atlantic coast of the Cape Peninsula in South Africa. A List of common misconceptions#Geography, common misconception is that the Cape of Good Hope is the southern tip of Afri ...

. This taxon is placed in the family Sparidae within the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Spariformes Spariformes is an order of ray-finned fishes consisting of six families within the series Percomorpha. Taxonomy Spariformes was first used as a taxonomic term in 1860 by the Dutch physician, herpetologist and ichthyologist Pieter Bleeker. Trad ...

by the 5th edition of ''

Fishes of the World ''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...

''. Some authorities classify this genus in the subfamily Boopsinae, but the 5th edition of Fishes of the World does not recognise subfamilies within the Sparidae.

Etymology

''Gymnocrotaphus'' combines ''gymnos'', meaning naked, and ''crotaphus'' meaning "cheek", a reference to the lack of scales on the cheeks of this species. 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 ...

, ''curvidens'', means "curved teeth", an allusion to the curved incisor-like teeth in rows in the front of each jaw.

Description

''Gymnocrotaphus'' has a naked head, except for some scales on the

gill cover The operculum is a series of bones found in bony fish and Chimaera, chimaeras that serves as a facial support structure and a protective covering for the gills; it is also used for respiration and feeding. Anatomy The opercular series contain ...

. There is a band of curved

incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

-like teeth in each jaw with a band of smaller conical teeth inside this and the very small molar-like teeth inside those. There are 10 spines and 11 or 12 soft rays supporting the

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 ...

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 ...

is supported by 3 spines and 9 or 10 soft rays. The body is rather plump and deep, its depth fitting into its

standard length Fish measurement is the measuring of individual fish and various parts of fish anatomy, their anatomies, for data used in many areas of ichthyology, including Taxonomy (biology), taxonomy and fishery biology. Overall length Standard length (SL) is ...

2.3 times. The dorsal profile of the headis concave in front of the eyes, and just above the eyes too. In life the colour of the body is coppery brown with a bluish grey head and blue eyes. Along exh scale row there are orange lines. This species has a maximum published

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

of .

Distribution and habitat

''Gymnoctotaphus'' is endemic to the southeastern Atlantic and southwestern Indian Oceans where it is endemic to the coasts of South Africa from

False Bay False Bay (Afrikaans: ''Valsbaai'') is a body of water in the Atlantic Ocean between the mountainous Cape Peninsula and the Hottentots Holland Mountains in the extreme south-west of South Africa. The mouth of the bay faces south and is demarc ...

in the Western Cape to Port St. Johns in the Eastern Cape">Port_St._Johns.html" ;"title="Western Cape to Port St. Johns">Western Cape to Port St. Johns in the Eastern Cape. This species is found at depths between on shallow reefs.

Biology

''Gymnocrotaphus'' is an omnivorous, feeding on sea squirts, bryozoans, Polychaete, polychaetes, algae and Crustacean, crustaceans. It is a sedentary species which tends to stay close to the reef in crevices and overhangs. Little is known about the biology of this species but it is thought it may be

hermaphroditic A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

Economic importance

Caught by shore anglers and spearfishers, with bag limit, prohibited for sale.

Conservation status

IUCN Status: Least concern. This species is considered to be effectively protected by no-take MPAs over its entire distributional range.

References

{{Taxonbar, from1=Q2507192, from2=Q2108876 Fish described in 1858 Fish of South Africa Sparidae