''Acentrophryne dolichonema'' 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 ...

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 ...

Linophrynidae, the leftvents, a family of deep sea anglerfishes. This species is only known from the eastern Pacific Ocean off the coast of Peru.

Taxonomy

''Acentrophryne dolichonema'' was first formally described in 2005 by the ichthyologists Theodore Pietsch and Mitsomi Shimazaki with its type locality given as off Peru at 8°10.6' to 11.9'S, 80°32.0'-32.4'W from waters where the bottom depth was . The 5th edition of ''Fishes of the World'' classifies this genus in the family Linophrynidae, within the

suborder Order () 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 recognized ...

Ceratioidei Ceratioidei, the deep-sea anglerfishes or pelagic anglerfishes, is a suborder of marine ray-finned fishes, one of five suborders in the order Lophiiformes, the anglerfishes. These fishes are found in tropical and temperate seas throughout the wor ...

, the deep sea anglerfishes, of the

anglerfish The anglerfish are ray-finned fish in the order Lophiiformes (). Both the order's common name, common and scientific name comes from the characteristic mode of predation, in which a modified dorsal Fish fin#Ray-fins, fin ray acts as a Aggressiv ...

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 ...

Lophiiformes The anglerfish are ray-finned fish in the order Lophiiformes (). Both the order's common and scientific name comes from the characteristic mode of predation, in which a modified dorsal fin ray acts as a lure for prey (akin to a human angler, ...

Evolutionary history

''Acentrophryne dolichonema'' is one of two species in the genus ''Acentophryne''. This genus is known from the fossil record, as a single specimen was found in 1977 from a

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

diatomaceous deposit in the

Puente Hills The Puente Hills are a chain of hills, one of the lower Transverse Ranges, in an unincorporated area in eastern Los Angeles County, California, Los Angeles County, California, in the United States. The western end of the range is often referred to ...

Southern California Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural List of regions of California, region that generally comprises the southern portion of the U.S. state of California. Its densely populated coastal reg ...

. This was initially tentatively identified as being '' A. longidens'' but its identity is now left open as ''Acentrophryne sp.'' as it was somewhat intermediate between the two known species. ''Acentrophryne'' leftvents are endemic to the eastern Pacific and are adapted to low oxygen environments. The fossil specimen from California suggests that this genus originated in the Miocene and that hypoxic environments were more widespread in the eastern Pacific, as these reduced the genus underwent a contraction in its distribution and subsequent

allopatric speciation Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...

Etymology

''Acentrophryne dolichonema'' belongs to the genus ''Acentophryne'', a name that prefixes ''a'', meaning "without", to ''kentron'', meaning "spine", a reference to the lack of a spine on the

preoperculum This glossary of ichthyology is a list of definitions of terms and concepts used in ichthyology, the study of fishes. A B C ...

. This is then suffixed with ''phryne'', which means "toad", commonly used in the names of anglerfish genera. Its use may date as far back as

Aristotle Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...

and

Cicero Marcus Tullius Cicero ( ; ; 3 January 106 BC – 7 December 43 BC) was a Roman statesman, lawyer, scholar, philosopher, orator, writer and Academic skeptic, who tried to uphold optimate principles during the political crises tha ...

, who referred to anglerfishes as "fishing-frogs" and "sea-frogs", respectively, possibly because of their resemblance to frogs and toads. 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 ...

, ''dolichonema'', is a compound of ''dolichos'', meaning "long" and ''nema'', which means "thread", an allusion to the long, filamentous appendage near the tip of the esca in this species.

Description

''Acentrophryne dolichonema'' has 3 soft rays in both the

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

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 ...

. This species is known only from

metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...

females and these are distinguished from the metamorphosed females of ''A. longeidens'' by the possession of a longer appendage on the tip of the esca, this being over 10 times longer than that of ''A. longidens'', and a longer

illicium ''Illicium'' is a genus of flowering plants treated as part of the family Schisandraceae,

, which has a length equivalent to between 63.6% to 70.5% of the

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 ...

. They also have a narrower head and fewer fin rays 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 ...

, 16 compared to 18 or 19 for ''A. longidens''. This species has a maximum published standard length of .

Distribution and habitat

''Acentrophryne dolichonema'' is apparently

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 Eastern Pacific and is known from three specimens collected from a single locality off northern Peru at depsth between .

References

{{taxonbar, from=Q5303279 Fish described in 2005 Taxa named by Theodore Wells Pietsch III dolichonema