The Spot-naped Butterflyfish (''Chaetodon oxycephalus''), also known as the pig-face butterflyfish, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 ...

. a

butterflyfish The butterflyfish are a group of conspicuous tropical ocean, marine fish of the family Chaetodontidae; the bannerfish and coralfish are also included in this group. The approximately 129 species in 12 genera are found mostly on the reefs of the ...

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 ...

Chaetodontidae. It is found in the Indo- West Pacific region from

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

, north to

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

and the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

. It grows to a maximum of long. The body is white with thin vertical lines on the sides and a large black area in the upper back. Very similar to the

Lined Butterflyfish The lined butterflyfish (''Chaetodon lineolatus'') is a species of marine ray-finned fish. a butterflyfish belonging to the family Chaetodontidae, one of the largest species in the genus ''Chaetodon''. It has a wide range from the Red Sea to Sou ...

(''C. lineolatus''), its vertical black eyestripe is broken above the eye and there are additional black and orange lines and spots in the yellow

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

and

caudal 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 only ...

s. The Spot-naped Butterflyfish belongs to the large

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

''Rabdophorus'' which might warrant recognition as a distinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

. In this group, it seems to be member of a lineage also containing species such as the Lined Butterflyfish, or the peculiar Black-wedged Butterflyfish (''C. falcula'') and

Pacific Double-saddle Butterflyfish ''Chaetodon ulietensis'', the Pacific double-saddle butterflyfish or false falcula butterflyfish, is a species of butterflyfish (family Chaetodontidae). It flourishes in coral-rich environments in the central Indo-Pacific region. Their range exte ...

or "False Falcula" (''C. ulietensis''). These four differ wildly in shape, but all have bluish vertical lines on a white body with yellow behind, and black on back and

caudal peduncle 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 only ...

in addition to the typical eyestripe of ''Chaetodon''. The Blue-cheeked Butterflyfish (''C. semilarvatus'') seems to be a far more basal lineage of ''Rabdophorus'' relative to them, but it also has the tell-tale blue vertical lines. ''C. oxycephalus'' is found in coral-rich areas and clear waters of seaward

reef A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geol ...

s at 10–40 m depth. It feeds on

coral polyp A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are roughly cylindrical in shape and elongated at the axis of the vase-shaped body. In solitary polyps, the aboral (opposite to oral) end i ...

s and

sea anemone Sea anemones ( ) are a group of predation, predatory marine invertebrates constituting the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemone ...

References

External links

* Chaetodon Fish of Palau Fish described in 1853 {{Chaetodontidae-stub