''Rhynchactis leptonema'' is a species of

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

ray-finned fish belonging to the family Gigantactinidae, the whipnose anglers. This species is known from widely scattered locations in the Atlantic and Pacific Oceans.

Taxonomy

''Rhynchactis leptonema'' was first formally described in 1925 by the English

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, 33,400 species of fish had been described as of Octobe ...

Charles Tate Regan with its type locality given as the western central Atlantic at 8°19'N, 44°35'W from a depth of around . When Regan described this species, he proposed a new

monospecific genus 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 ...

Rhynchactis ''Rhynchactis'' is a genus of deep-sea anglerfish in the family Gigantactinidae, containing three species found worldwide at depths greater than . Adult female ''Rhynchactis'' reach a standard length (SL) of and have a dark-colored, streamline ...

'', so this species is the type species of that genus by

monotypy 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 ...

. The genus ''Rhynchactis'' is one of two genera in the family Gigantactinidae that 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 ...

'' classfies 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 ...

Ceratioidei, the deep sea anglerfishes of 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 ...

Lophiiformes, the anglerfishes.

Etymology

''Rhynchactis leptonema'' is a member of the genus ''Rhynchactis'', the name of which is a combination of ''rhynchos'', meaning "snout", with ''actis'', which means "ray", an allusion to the illicium originating at the tip of the snout. 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 ...

, ''leptonema'', means "slender thread", a reference to the long and thin illicium.

Description

''Rhynchactis leptonema'' has metamorphosed females that are slender and streamlined, with a relatively small head comprising about a quarter of the standard length. The illicium originates at the front of the blunt head and exceeds the length of the body. In this species, the illicium has a length equivalent to 118% to 187% of the

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 the fish. In contrast to most other deep-sea anglerfishes, the illicium does not bear a bioluminescent esca at the tip. The upper jaw extends past the lower; the dentition is greatly reduced, particularly in larger females, consisting of only 0–2 tiny, curved teeth on each side at the tip of the upper jaw, and sometimes also fine teeth in the lower jaw. Uniquely, the inside of both jaws are densely covered by white, papilla-like glands, each containing a short, pigmented tube at the center lined by glandular cells. The maximum published total length is .

Distribution and habitat

''Rhynchactis leptonema'' has been recorded from the western Atlantic and from the Pacific off Hawaii and Taiwan and is known from only five specimens, which were taken at depths between 0 and .

References

{{Taxonbar, from=Q2483136

leptonema ''Leptonema'' is a genus of flowering plant belonging to the family Phyllanthaceae first described in 1824. The entire genus is endemic to Madagascar. It is dioecious, with male and female flowers on separate plants. ;Species # '' Leptonema g ...

Taxa named by Charles Tate Regan Fish described in 1925