''Bostrychus expatria'' 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), ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

fish in the family

Butidae Butidae is a family of sleeper gobies in the order Gobiiformes. The family was formerly classified as a subfamily of the Eleotridae but the 5th Edition of ''Fishes of the World'' classifies it as a family in its own right. Molecular phylogenetic ...

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 Lake Manguao on the island of

Palawan Palawan (, ), officially the Province of Palawan (; ), is an archipelagic province of the Philippines that is located in the region of Mimaropa. It is the largest province in the country in terms of total area of . The capital and largest c ...

in the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

Anatomy and morphology

''Bostrychus expatria'' is a small fish reaching a length of . They appear as standard members of their family, with non-hydrodynamically-shaped bodies typical of bottom-dwelling fish. It possesses two completely separate

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 ...

s, the first one supported by spines. The caudal fin is truncately-shaped, usually not much thicker than the peduncle itself. Its eyes are located dorsally, another trait commonly seen in

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

fish.

Range and distribution

''Bostrychus expatria'' has a single known population that can be found only in Lake Manguao in the Philippines. Lake Manguao is a freshwater lake located in the hilly areas in the northern part of the Philippine island of

. The lake has at least four brooks draining into it, yet it has no rivers draining out from it. ''O. expatriata'' shares the lake with at least two other endemic species of fish from the family

Cyprinidae Cyprinidae is a family of freshwater fish commonly called the carp or minnow family, including the carps, the true minnows, and their relatives the barbs and barbels, among others. Cyprinidae is the largest and most diverse fish family, and t ...

Ecology

Owing to the remoteness of its

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

, there have been extremely few studies on this species. The few ones that have been done describe the fish as a benthic species, spending much of its time resting on the lake's bottom. Despite its size, ''B. expatriata'' is predatory, known to feed mostly on the small crustaceans that make the lake's muddy bottom their home. It has also been known to ingest small fishes.

Importance to humans

As a small freshwater fish in an island with rich marine resources, ''B. expatria'' has no known commercial value. The fish may be caught as bycatch by small cast nets as fishing in the lake is done by the local population. It is known as ''bulokot'' by the natives living around the lake.

Conservation

In 1996, the World Conservation Monitoring Centre assessed the fauna of Lake Manguao and ''B. expatria'' (as ''Boroda expatria'') was classified as VULNERABLE. As ''B. expatria'' has one known population in a single freshwater lake, its fate is inextricably tied to its home lake's. The fish population is extremely vulnerable to anthropogenic disturbance such as pollution and overfishing, and a slight disturbance to the balance of the lake could send the species to extinction. In theory, the entire island of Palawan has been declared a wildlife preserve which should ensure the survival of the species, but wildlife laws are rarely enforced or followed in the country.

Tilapia Tilapia ( ) is the common name for nearly a hundred species of cichlid fish from the coelotilapine, coptodonine, heterotilapine, oreochromine, pelmatolapiine, and tilapiine tribes (formerly all were "Tilapiini"), with the economically mos ...

, a fish known for disrupting and destroying the natural balance of the ecosystems it invades, was introduced into the lake in 1992. The presence of this voracious species may drive ''B. expatria'' into extinction.

Etymology and taxonomic history

The species name, ''expatria'' was originally chosen by Herre to describe the fish as an

expatriate An expatriate (often shortened to expat) is a person who resides outside their native country. The term often refers to a professional, skilled worker, or student from an affluent country. However, it may also refer to retirees, artists and ...

. ''Bostrychus expatria'' was originally described by Herre as ''Boroda expatria''. ''Boroda'' was derived from the

Visayan Visayans ( Cebuano: ''mga Bisayà'' ) are a Philippine ethnolinguistic family group or metaethnicity native to the Visayas, to the southernmost islands south of Luzon, and to a significant portion of Mindanao. They are composed of numerous di ...

word ''borod'', which was used by the natives of the lake to refer to goby-like fishes. The name remained until 1997 when it was redesignated into the genus ''

Bostrychus ''Bostrychus'' is a genus of fishes in the family Butidae mostly native to eastern Asia to Australia with one species being found along the Atlantic coast of Africa. While some of these species are restricted to freshwater, most can be found in ...

'' (as ''Bostrychus expatria'') by Eschmeyer.

References

{{Taxonbar, from=Q21996015 Butidae Freshwater fish of the Philippines Endemic fauna of the Philippines Fauna of Palawan Fish described in 1927 Taxa named by Albert William Herre Taxobox binomials not recognized by IUCN