The Colares stingray, ''Dasyatis colarensis'', is a

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

stingray Stingrays are a group of sea rays, which are cartilaginous fish related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatid ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Dasyatidae, native to the shallow

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

s of the Amazon River

estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

in northern

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. This species inhabits inshore bays during the

dry season The dry season is a yearly period of low rainfall, especially in the tropics. The weather in the tropics is dominated by the tropical rain belt, which moves from the northern to the southern tropics and back over the course of the year. The ...

and moves away from the coast in the

rainy season The rainy season is the time of year when most of a region's average annual rainfall occurs. Rainy Season may also refer to: * ''Rainy Season'' (short story), a 1989 short horror story by Stephen King * "Rainy Season", a 2018 song by Monni * '' ...

. It is characterized by a rhomboid

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

disk, elongated snout, and a dark band on the lower lip. A fairly large species, males and females attain disk widths of and respectively. Females give birth to 1–4 young, possibly annually. Colares stingrays are both targeted and caught as

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juven ...

by Brazilian

artisanal An artisan (from french: artisan, it, artigiano) is a skilled craft worker who makes or creates material objects partly or entirely by hand. These objects may be functional or strictly decorative, for example furniture, decorative art, ...

and

commercial fisheries Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must oft ...

; these pressures coupled with its small range and slow reproductive rate has led the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natur ...

(IUCN) to list this species as critically endangered.

Taxonomy

The Colares stingray was described by Hugo Santos, Ulisses Gomes, and Patricia Charvet-Almeida in 2004, in the

scientific journal In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. Content Articles in scientific journals are mostly written by active scientists such ...

''Zootaxa''. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

refers to Colares Island in Marajó Bay, where the

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes the ...

, a long mature male, was caught.

Distribution and habitat

The range of the Colares stingray appears restricted to the mouth of the Amazon River in northern

, in the

estuarine An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environmen ...

area affected by the river's

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does in ...

discharge; it may also occur in adjacent areas as far as

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in ...

. Found to a depth of , this species conducts annual movements that are influenced by

salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

: in the

it is found in the coastal bays such as Marajó, while in the

it leaves the bays and shifts offshore.

Description

The Colares stingray has a diamond-shaped

disk about as long as wide, with rounded margins and a long snout that tapers to a point. The snout of the female is shorter than that of the male, and snout edges dip in slightly near the tip. The eyes are small and followed by large spiracles. There is a flap of skin between the

nare A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called t ...

s with a fringed rear margin and rounded corners. The lower lip is bow-shaped and lined by a distinctive straight, dark band. The dentition is

sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

: males have pointed, recurved teeth in 43–45 upper tooth rows and 45–60 lower tooth rows, while females have flat-crowned teeth in 66–77 upper tooth rows and 75–77 lower tooth rows. There are 3–4

papilla Papilla (Latin, 'nipple') or papillae may refer to: In animals * Papilla (fish anatomy), in the mouth of fish * Basilar papilla, a sensory organ of lizards, amphibians and fish * Dental papilla, in a developing tooth * Dermal papillae, part of ...

e in a transverse row on the floor of the mouth, which may have forked tips. The

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two e ...

s are triangular, with the pointed tips extending past the disk. The tail is long and whip-like, measuring more than twice the disk length. A stinging spine with 69–70 serrations and sometimes a low keel are positioned on top of the tail, while a low fin fold runs underneath. Small, flattened tubercles are randomly arranged along the dorsal midline from the base of the tail to between the eyes, thinning out towards the tip of the snout. Females also have tubercles on the underside. The dorsal coloration is a uniform light brown, becoming darker on the tail and

claspers In biology, a clasper is a male anatomical structure found in some groups of animals, used in mating. Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve to channel semen into the female's c ...

(in males), and with a light trailing margin on the pelvic fins. The underside is pale, darkening towards the fin margins. Males reach long and across, while females reach long and across.

Biology and ecology

Like other stingrays, the Colares stingray is

aplacental viviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...

; only recently impregnated females can be found inshore, suggesting that the annual movements of this species may relate to reproduction. Observed litter sizes range from 1 to 4, and the reproductive cycle may last one year.

Human interactions

The

(IUCN) has assessed the Colares stingray as critically endangered, citing its limited geographic distribution, likely slow reproductive rate, and susceptibility to

fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment, but may also be caught from stocked bodies of water such as ponds, canals, park wetlands and reservoirs. Fishing techniques ...

gear. This species is abundant in Marajó Bay during the dry season. It is taken as

and

targeting

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

in the Amazon estuary. In addition, industrial fishing vessels from the

Brazilian state The federative units of Brazil ( pt, unidades federativas do Brasil) are subnational entities with a certain degree of autonomy (self-government, self-regulation and self-collection) and endowed with their own government and constitution, which ...

Pará Pará is a state of Brazil, located in northern Brazil and traversed by the lower Amazon River. It borders the Brazilian states of Amapá, Maranhão, Tocantins, Mato Grosso, Amazonas and Roraima. To the northwest are the borders of Guyana a ...

began to fish directly for this species in the 2000s, with their catches exported to

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...

. The IUCN has recommended that Brazil implement habitat conservation and fishery management schemes.

References

{{Taxonbar, from=Q148830 Fontitrygon Fish described in 2004 Taxonomy articles created by Polbot