''Hoplichthys'', the ghost flatheads, is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 ...

es native to the

Indian Indian or Indians may refer to: Peoples South Asia * Indian people, people of Indian nationality, or people who have an Indian ancestor ** Non-resident Indian, a citizen of India who has temporarily emigrated to another country * South Asia ...

and

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

s. This genus is the only member of 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 ...

Hoplichthyidae.

Taxonomy

Hoplichthys was first proposed as a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus in 1829 by the French

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 ...

Georges Cuvier when he described its

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

, and only species at that time, ''H. langsdorfi'' from Japan. In 1873 the German naturalist

Johann Jakob Kaup Johann Jakob von Kaup (10 April 1803 – 4 July 1873) was a German naturalist. A proponent of natural philosophy, he believed in an innate mathematical order in nature and he attempted biological classifications based on the Quinarian system. Kaup ...

considered that the genus ''Hoplichthys'' was so different from other "flathead" taxa that it merited placing in a

monogeneric In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

family, the Hoplichthyidae. The 5th edition of ''

Fishes of the World ''Fishes of the World'' by the American ichthyologist Joseph S. Nelson (1937–2011) is a standard reference for fish systematics. Now in its fifth edition (2016), the work is a comprehensive overview of the diversity and classification of the ...

'' classifies this family within the

suborder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

Platycephaloidei Platycephaloidei is a suborder of ray-finned fishes, part of the order Scorpaeniformes, and includes the flatheads, ghost flatheads and sea robins. Taxonomy Platycephaloidei was first recognised and named as a taxonomic grouping in 1943 by th ...

in the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Scorpaeniformes The Scorpaeniformes are a diverse order of ray-finned fish, including the lionfishes and sculpins, but have also been called the Scleroparei. It is one of the five largest orders of bony fishes by number of species, with over 1,320. They are ...

. Other authorities differ and do not consider the Scorpaeniformes to be a valid order because the

Perciformes Perciformes (), also called the Percomorpha or Acanthopteri, is an order or superorder of ray-finned fish. If considered a single order, they are the most numerous order of vertebrates, containing about 41% of all bony fish. Perciformes means ...

is not

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

without the taxa within the Scorpaeniformes being included within it. These authorities consider the Platycephalidae to belong to the

, along with the families

Bembridae Bembridae, the deep-water flatheads, are a family of bottom-dwelling ray-finned fishes. They are found in the Indian and western Pacific Oceans. Taxonomy Bembridae was first proposed as a family in 1873 by the German zoologist Johann Jakob Kaup ...

, Parabembridae,

Platycephalidae The Platycephalidae are a family of marine fish, most commonly referred to as flatheads. They are relatives of the popular lionfish, belonging to the order Scorpaeniformes. Taxonomy Platycephalidae was first proposed as a family in 1839 by the E ...

and Plectrogeniidae within the Perciformes. However, some workers have put forward evidence that there may be a rather surprising

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

relationship between this family and the

gobies Gobiidae or gobies is a family of bony fish in the order Gobiiformes, one of the largest fish families comprising more than 2,000 species in more than 200 genera. Most of gobiid fish are relatively small, typically less than in length, and the ...

as they share more seemingly unique derived characters with each other than with other taxa, this needs to be further investigated,.

Etymology

''Hoplichthys'' combines ''hoplo'', meaning "armed", with ''ichthys'', which means fish. There is series of large bony plates on the body of ''H. langsdorfii'', each of which bears two spines and this is thpought what the first part of the genus name refers to. Cuvier spelled it as ''Oplichthys'' in hist text but it was ''Hoplichthys'' in the table of contents and this is the prevailing usage.

Species

There are currently 17 recognized species in this genus: * '' Hoplichthys acanthopleurus''

Regan The family name Regan, along with its cognates O'Regan, O Regan, Reagan, and O'Reagan, is an Anglicized form of the Irish surname Ó Riagáin or Ó Ríogáin, from Ua Riagáin. The meaning is likely to have originated in ancient Gaelic ''ri'' ...

, 1908 * '' Hoplichthys citrinus'' C. H. Gilbert, 1905 (Lemon ghost flathead) * '' Hoplichthys fasciatus''

Matsubara is a city located in Osaka Prefecture, Japan. , the city had an estimated population of 117,811 in 57351 households and a population density of 7100 persons per km². The total area of the city is . Geography Matsubara is located in the cente ...

, 1937 * '' Hoplichthys filamentosus'' Matsubara &

Ochiai Ochiai (written: ) is a Japanese surname. Notable people with the surname include: *, Japanese voice actor *, Japanese judoka, karateka and writer *, Japanese baseball player and manager *, Japanese footballer *, Japanese film director *, Japanese ...

, 1950 (Long-ray ghost flathead) * '' Hoplichthys gilberti'' D. S. Jordan & R. E. Richardson, 1908 * '' Hoplichthys gregoryi'' ( Fowler, 1938) * '' Hoplichthys haswelli''

McCulloch McCulloch is a Scottish surname. It's a variation of the Northern Irish surname McCullough. It's commonly found in Galloway. Notable people with the surname include: *Alan McCulloch (politician), New Zealand politician *Alan McLeod McCulloch ( ...

, 1907 (Armoured flathead) * '' Hoplichthys imamurai''

Nagano Nagano may refer to: Places * Nagano Prefecture, a prefecture in Japan ** Nagano (city), the capital city of the same prefecture *** Nagano 1998, the 1998 Winter Olympics *** Nagano Olympic Stadium, a baseball stadium in Nagano *** Nagano Universi ...

, McGrouther &

Yabe was a village located in Yame District, Fukuoka Prefecture, Japan. Yabe is located at 330m above sea level. The average temperature is 14 °C and the average annual precipitation is 2,706mm. As of 2006, the village had an estimated popula ...

, 2013 (Imamura's ghost flathead) Nagano, Y., McGrouther, M.A. & Yabe, M. (2013): A new species of the hoplichthyid genus ''Hoplichthys'' (Teleostei: Hoplichthyidae) from northern Western Australia. ''Zootaxa, 3681 (3): 241–248.'' * '' Hoplichthys langsdorfii''

Cuvier Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French naturalist and zoologist, sometimes referred to as the "founding father of paleontology". Cuvier was a major figure in nat ...

, 1829 * '' Hoplichthys mcgroutheri'' Nagano, Imamura & Yabe, 2014 (McGrouther's ghost flathead) Nagano, Y., Imamura, H. & Yabe, M. (2014): A new ghost flathead (Scorpaeniformes: Hoplichthyidae) from southwestern Australia. ''Ichthyological Research, 62 (3): 245-252.'' * '' Hoplichthys mimaseanus'' Nagano, Endo & Yabe, 2013 Nagano, Y., Endo, H. & Yabe, M. (2013): ''Hoplichthys mimaseanus'', a New Ghost Flathead from East Asia and Western Australia (Teleostei: Hoplichthyidae). ''Bulletin of the National Museum of Natural Science, Ser. A., Supplement No. 7: 1–9.'' * '' Hoplichthys ogilbyi'' McCulloch, 1914 (Ogilby's ghost flathead) * '' Hoplichthys pectoralis'' (Fowler, 1943) * '' Hoplichthys platophrys'' C. H. Gilbert, 1905 * '' Hoplichthys prosemion'' (Fowler, 1938) * ''

Hoplichthys regani ''Hoplichthys'', the ghost flatheads, is a genus of marine ray-finned fishes native to the Indian and Pacific Oceans. This genus is the only member of the family Hoplichthyidae. Taxonomy Hoplichthys was first proposed as a monotypic genus in 18 ...

'' D. S. Jordan, 1908 (Ghost flathead) * '' Hoplichthys smithi'' (Fowler, 1938)

Characteristics

''Hoplichthys'' ghost flatheads have a very wide, flattened head, an elongate body which has no scales but does have many spines and ridges on the upper body, There is a row of large spined bony plates, called scutes, running along the middle of the flanks. The lowermost 3 to 5 fin rays of 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 ...

are separated from the membrane. There are no spines in 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 ...

and they have 26 vertebrae. They have large mouths with tiny villiform teeth in the jaws, on the

vomer The vomer (; lat, vomer, lit=ploughshare) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxill ...

, on the

palatine A palatine or palatinus (in Latin; plural ''palatini''; cf. derivative spellings below) is a high-level official attached to imperial or royal courts in Europe since Roman times.

and in the pharynegeals. There are two separate

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 ...

s, the first is short-based and contains 6 or 7 spines and the second is long-based and contains between 13 and 16 soft rays. The

has a single spine and between 15 and 17 soft rays and is around the same length as the second dorsal fin. 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 ...

can be rounded or it can be

emarginate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

. 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 en ...

s are located on the thoraxand have a single spine and 5 soft rays. The majority of the species are yellow, pinkish, or brown in colour on the upper body and flanks, with various spots and mottles, and they are pink, white or silver ventrally. The pectoral fins vary in colour from yellowish brown to hyaline marked with crossbarring, spotting or mottling. The first dorsal fin is frequently dark towards its rear, or has wavy line across it. The caudal fin is typically hyaline, although in some species it has a dark distal margin or spots at the base. The maximum length attained by these fishes varies from a

standard 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 m ...

of in ''H. fasciatus'' to in ''H. haswelli''.

Distribution, habitat and biology

''Hoplichthys'' ghost flatheads have an Indo-Pacific distribution, occurring from the eastern coast of Africa to Hawaii. they are benthic fishes living on the bottom in

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

and

slope In mathematics, the slope or gradient of a line is a number that describes both the ''direction'' and the ''steepness'' of the line. Slope is often denoted by the letter ''m''; there is no clear answer to the question why the letter ''m'' is use ...

waters at depths between . The

larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

and juveniles are found in shallower water than the adults. These fishes prey on a variety of crustaceans and other fishes.

References

{{Taxonbar, from=Q2729700 Platycephaloidei Hoplichthyidae Taxa named by Georges Cuvier