''Easchmeyer nexus'' is a

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

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 ...

; it is the only species in the

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 Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

''Eschmeyer'' and monogeneric

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 ...

Eschmeyeridae. This fish is only known from the

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 contine ...

, near Fiji.

Taxonomy

''Eschmeyer nexus'' was first formally described in 1983 by the American ichthyologists Stuart G. Poss and Victor G. Springer with the type locality given as Fiji. Poss and Springer placed their new species in the new monotypic genus ''Eschmeyer'' and in 2001

Sergey Anatolyevich Mandritsa Sergey may refer to: * Sergey (name), a Russian given name (including a list of people with the name) * Sergey, Switzerland, a municipality in Switzerland * ''Sergey'' (wasp), a genus in subfamily Doryctinae The Doryctinae or doryctine wasps are ...

classified that genus within the monogeneric family Eschmeyeridae, The 5th edition of ''

Fishes of the World ''Fishes of the World'' by the American Ichthyology, 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 classificat ...

'' classifies the 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 ...

Scorpaenoidei Scorpaenoidei is a suborder of ray-finned fishes, part of the order Scorpaeniformes, that includes the scorpionfishes, lionfishes and velvetfishes. This suborder is at its most diverse in the Pacific and Indian Oceans but is also found in the At ...

which in turn is classified within 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 ...

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 k ...

. Other authorities place the Scorpaenoidei within 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 ...

. A recent study placed the genus ''Eschmeyer'' into an expanded stonefish clade, the Synanceiidae, because all of these fish have a lachrymal sabre that can project a switch-blade-like mechanism out from underneath their eye. The name of both the genus and family honours William N. Eschmeyer, an American ichthyologist at the California Academy of Sciences, or his work on the Scorpaenid fishes. The specific name ''nexus'', is derived from , Latin for 'tie' or 'connect', a reference to the suite of features suggesting this taxon has a close relationship with a number of groups within the Scorpaenoidei. Mandritsa suggested the English common name of ''cofish'' in recognition of Eschmeyer’s participation in the ''

Catalog of Fishes Catalog of Fishes is a comprehensive on-line database and reference work on the scientific names of fish species and genera. It is global in its scope and is hosted by the California Academy of Sciences. It has been compiled and is continuously u ...

''.

Description

''Eschmeyer nexus'' has eight spines and thirteen soft rays in the

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 ...

, with the first few dorsal fin spines being very short, 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 ...

has three spines and eight soft rays. All the fin rays are unbranched. The front part of the throat, the isthmus, does not have any fleshy papillae and the gill membranes do not have a wide junction with the isthmus. The frontal and parietal bones are well developed. There are no spines on the preorbital bone. The only scales are those on the lateral line which has ten tubed scales. There are no spiny projections to the rear of the

caudal peduncle 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 ...

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 ...

membrane is joined to the body and is fused to the membrane of opposite pelvic fin. There is no detached

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 ...

ray. This is a small fish with a maximum

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 ...

of .

Distribution and habitat

''Eschmeyer nexus'' is found in the western central Pacific Ocean where it has only been recorded from Fiji. It is a

demersal fish Demersal fish, also known as groundfish, live and feed on or near the bottom of seas or lakes (the demersal zone).Walrond Carl . "Coastal fish - Fish of the open sea floor"Te Ara - the Encyclopedia of New Zealand. Updated 2 March 2009 They o ...

References

{{Taxonbar, from2=Q2681788, from1=Q289456, from3=Q1926873 Scorpaenoidei Taxa named by Victor G. Springer Taxa named by Stuart G. Poss Fish described in 1983