''Tydemania navigatoris'', the fleshy-lipped spikefish, 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 ...

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 ...

Triacanthodidae, the spikefishes. This species is found in the Indian and Pacific Oceans where it occurs at depths of from . This species grows to a length of SL. This fish is specialized to feed on the scales of other fishes. This species is the only known member of the

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 ...

''Tydemania''.

Taxonomy

''Tydemania navigatoris'' was first formally described in 1913 by the German-born Dutch

zoologist Zoology ( , ) is the scientific study of animals. Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. Zoology is one ...

and

biogeographer Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...

Max Carl Wilhelm Weber Max Carl Wilhelm Weber van Bosse or Max Wilhelm Carl Weber (5 December 1852 – 7 February 1937) was a German- Dutch zoologist and biogeographer. Weber studied at the University of Bonn, then at the Humboldt University in Berlin with the z ...

, with its type locality given as Madura Sea at 7°15'S, 115°15.6'E, Siboga station 12, from a depth of . When Weber described this species, he proposed the 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 "unispe ...

''Tydemania'' for it. This taxon is classified in the family Triacanthodidae and of the subfamily Triacanthodinae. The 5th edition of ''

Fishes of the World ''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...

'' classifies the family Triacanthodidae in 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 ...

Triacanthoidei Triacanthoidei is a suborder of ray-finned fishes belonging to the order Tetraodontiformes, which includes the pufferfishes, triggerfishes and related taxa. These benthic fishes are mainly found in the Indian Ocean with some of the spikefishes fou ...

in the order Tetraodontiformes.

Etymology

''Tydemania navigatoris'' is the only species in the monotypic genus ''Tydemania''; this name suffixes ''-ia'', meaning "of" or "belonging to", to the surname of Lieutenant Gustaaf Frederik Tydeman who was captain of the Dutch research vessel ''Siboga'', from which the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

was collected. 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 ...

, ''navigatoris'', means "sailor" or "mariner", an allusion Weber did not explain but it may be a reference to Tydeman's occupation.

Description

''Tydemania navigatoris'' has its

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

supported by 6 spines and between 13 and 15 soft rays. The first 3 spines are well developed but the last 3 are highly reduced and are just visible. The

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 ...

has between 12 and 14 soft rays while the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s have a single spine and may have a single soft ray. The snout is shorter than the remainder of the head and the lips are thick, swollen and fleshy. The teeth are compressed from the front to the back, broad and flattened towards the tip with a single row in each jaw. The

gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

slit extends to the lower half of the base of 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 ...

. The

pelvis The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...

has a scaly ventral surface which tapers to a point towards the tail and between the pelvic fin spines it is around four times as wide as the length of the pelvic fin base. The overall colour is typically a uniform red, but some specimens from Japan have a blue strip running along the body from above the eye to halfway along the body. This species has a maximum published

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 ...

of .

Distribution and habitat

''Tydemania navigatoris'' has an

Indo-West Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the s ...

distribution and it has been recorded to be found in East Africa, the

Bay of Bengal The Bay of Bengal is the northeastern part of the Indian Ocean. Geographically it is positioned between the Indian subcontinent and the Mainland Southeast Asia, Indochinese peninsula, located below the Bengal region. Many South Asian and Southe ...

, Japan, China, Philippines, Indonesia, and Australia. This 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 oc ...

which is found at depths between .

References

{{Taxonbar, from=Q199298, from2=Q2036404 Triacanthodinae Taxa named by Max Carl Wilhelm Weber Fish described in 1913