''Equulites popei'', Pope's ponyfish, 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 ...

, a

ponyfish Leiognathidae, the ponyfishes, slipmouths or slimys / slimies, are a small family of fishes in the order Perciformes. They inhabit marine and brackish waters in the Indian and West Pacific Oceans. They can be used in the preparation of ''bagoo ...

from 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 ...

Leiognathidae Leiognathidae, the ponyfishes, slipmouths or slimys / slimies, are a small family of fishes in the order Perciformes. They inhabit marine and brackish waters in the Indian and West Pacific Oceans. They can be used in the preparation of ''bagoo ...

. It has a wide

Indo-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 ...

distribution which extends from the

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

east to the western Pacific Ocean. It has entered the Mediterranean as a

Lessepsian migrant The Lessepsian migration (or Erythrean invasion) is the migration of marine species along the Suez Canal, usually from the Red Sea to the Mediterranean Sea, and more rarely in the opposite direction. When the canal was completed in 1869, fish, ...

. It was formerly considered to be

synonymous A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

with the elongate ponyfish (''

Equulites elongatus ''Equulites elongatus'', the slender ponyfish, also called the elongate ponyfish, elongate slimy or elongated slipmouth, is a marine fish of the family Leiognathidae native to the western Pacific and Indian Oceans. Description ''Equulites elong ...

'').

Description

''Equulites popei'' differs from the other members of the ''E. elongatus''

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

by having an eye diameter which is 82–137% of the length of the head to the rear of the eye. In addition, the distance from

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 ...

insertion to the centre of anus is a third to a half of that from the pelvic fin insertion to origin of 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 ...

. The upper flanks have large dark blotches which occasionally create up to 2 ring markings and there are sometimes up to 5 dark spots which are less than 50% of the diameter of the pupil. The head and lower flanks and belly are nearly a uniformly silvery white. The tip of the snout is blackish. The upper rear edge of the gill cover is light yellow. The upper flanks and back are silvery brown interspersed with dark blotches. The pectoral fin is pale yellow, there are black lines along the rays of the

caudal 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 only ...

which has a dark margin and all of the other fins are colourless. The maximum recorded

total length Fish measurement is the measuring of individual fish and various parts of their anatomies, for data used in many areas of ichthyology, including taxonomy and fishery biology. Overall length Standard length (SL) is the length of a fish measured f ...

is .

Distribution

''Equulites popei'' has an

distribution. Its range extends from the Red Sea and the coast of

East Africa East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...

east to the Philippines and north to Japan. It was recorded as ''E. elongatus'' for the first time in the Mediterranean Sea off Israel in 2011, and more recently off Lebanon and Turkey where it remains rare.Atlas of Exotic Fishes in the Mediterranean Sea (''Equulites popei''). 2nd Edition. 2021. 366p. CIESM Publishers, Paris, Monaco.https://ciesm.org/atlas/fishes_2nd_edition/Equulites_popei.pdf

Habitat and biology

''Equulites popei'' is found in shallow waters, where it is normally encountered in schools close to the bottom. It feeds mostly on small

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

polychaetes Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are m ...

and

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

Taxonomy

''Equulites popei'' was first formally described in 1932 as ''Macilentichthys popei'' by the

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

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, 35,800 species of fish had been described as of March 2 ...

Gilbert Percy Whitley (1903–1975) with the type locality given as

Kagoshima , is the capital Cities of Japan, city of Kagoshima Prefecture, Japan. , the city had an estimated population of 583,966 in 285,992 households, and a population density of 1100 persons per km2. The total area of the city is . Etymology While the ...

, Japan. Whitley did not specify the identity of the person honoured in its

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 ...

but since he was replacing the preoccupied name ''elongatus'' given to this species by the

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, p ...

ichthyologists

Hugh McCormick Smith Hugh McCormick Smith, also H. M. Smith (November 21, 1865 – September 28, 1941) was an American ichthyologist and administrator in the United States Bureau of Fisheries. Biography Smith was born in Washington, D.C. In 1888, he received a Doc ...

(1865–1941) and Thomas E.B. Pope then it is likely that Pope was being honoured. Until recently ''E. popei'' was considered synonymous with ''E. elongatus'' but ''E. elongatus'' is now considered a species complex with ''E. popei'' and the Red Sea elongate ponyfish (''

Equulites aethopos ''Equulites'' is a genus of ponyfishes native to the Indian Ocean and the western Pacific Ocean. Analysis of mitochondrial DNA published in 2017 has suggested that ''Equulites elongates'' is in fact a species group made up of three species ''Equ ...

'').

References

{{Taxonbar, from=Q99853190 popei Fish of the Indian Ocean Fish of the Pacific Ocean Fish of the Mediterranean Sea Fish described in 1932 Taxa named by Gilbert Percy Whitley