The pearl stingray (''Fontitrygon margaritella'') is a little-known

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), ...

stingray Stingrays are a group of sea Batoidea, rays, a type of cartilaginous fish. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatidae (deepwate ...

in 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 ...

Dasyatidae, found in shallow coastal waters from

Mauritania Mauritania, officially the Islamic Republic of Mauritania, is a sovereign country in Maghreb, Northwest Africa. It is bordered by the Atlantic Ocean to the west, Western Sahara to Mauritania–Western Sahara border, the north and northwest, ...

Angola Angola, officially the Republic of Angola, is a country on the west-Central Africa, central coast of Southern Africa. It is the second-largest Portuguese-speaking world, Portuguese-speaking (Lusophone) country in both total area and List of c ...

, though fossils have been found in Portugal. Growing to across, this species has a rounded

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 ...

disc with a pointed snout, and a wide band of

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scale (zoology), scales, which can also provide effective Underwater camouflage, camouflage through the us ...

s over the back in adults. It closely resembles and is often confused for the much larger daisy stingray (''F. margarita''); both species are characterized by the presence of an enlarged,

nacre Nacre ( , ), also known as mother-of-pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer. It is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is ...

ous denticle in the middle of the back called a "pearl spine". The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

(IUCN) assesses the pearl stingray's

conservation status The conservation status of a group of organisms (for instance, a species) indicates whether the group still exists and how likely the group is to become extinct in the near future. Many factors are taken into account when assessing conservation ...

as Near Threatened, but it is likely that most of the historically reported

fishery Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish far ...

catches of the daisy stingray were in fact of this species.

Taxonomy and phylogeny

Prior to being described by

Leonard Compagno Leonard Joseph Victor Compagno (1943-2024) was an international authority on shark taxonomy and the author of many scientific papers and books on the subject, best known of which is his 1984 catalogue of shark species produced for the Food and Agri ...

and Tyson Roberts, in a 1984 paper for the ''Proceedings of the California Academy of Sciences'', the pearl stingray was generally lumped together with the daisy stingray in scientific literature. However, its existence had been recognized since at least 1965. The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

''margaritella'' comes from the diminutive of the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word ''margarita'', meaning "pearl", in reference to the smaller body and pearl spine sizes of this ray compared to the daisy stingray. The

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

is a male across, from Mbode,

Cameroon Cameroon, officially the Republic of Cameroon, is a country in Central Africa. It shares boundaries with Nigeria to the west and north, Chad to the northeast, the Central African Republic to the east, and Equatorial Guinea, Gabon, and the R ...

. In appearance, the pearl stingray resembles the daisy stingray and the

Niger stingray The Niger stingray or smooth freshwater stingray (''Fontitrygon garouaensis'') is a species of stingray in the family Dasyatidae, native to rivers in Nigeria and Cameroon. Attaining a width of , this species can be distinguished by its thin, alm ...

(''Fontitrygon garouaensis''), both also native to

West Africa West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...

, suggesting that the three species are closely related. Lisa Rosenberger's 2001

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analysis, based on

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

, found that the pearl stingray is the

sister species In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

of the sharpnose stingray (''Maculabatis gerrardi''), and that the two form a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

with the pale-edged stingray (''Telatrygon zugei'') and the

smooth butterfly ray The smooth butterfly ray (''Gymnura micrura'') is a species of Chondrichthyes, cartilaginous fish in the family Gymnuridae. It is a member of the order Myliobatiformes, which contains 10 total families. Its natural habitats are shallow seas, subt ...

(''Gymnura micrura''). These results support the growing consensus that neither ''Dasyatis'' nor ''

Himantura ''Himantura'' is a genus of stingray in the family (biology), family Dasyatidae that is native to the Indo-Pacific. In a 2016 Taxonomy (biology), taxonomic revision, many of the species formerly assigned to ''Himantura'' were reassigned to other ...

'' are

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

. The daisy and Niger stingrays were not included in the study.

Distribution and habitat

The pearl stingray is found along the western coast of

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

, from Cape Blanc in

. This

bottom-dwelling 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". ...

species inhabits shallow, coastal marine and

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 estuary ...

s, and has been reported from

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') an ...

s and

estuaries 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 ...

, including the mouth of the

Congo River The Congo River, formerly also known as the Zaire River, is the second-longest river in Africa, shorter only than the Nile, as well as the third-largest river in the world list of rivers by discharge, by discharge volume, following the Amazon Ri ...

Description

The pearl stingray has a moderately thin, oval-shaped

disc about as long as wide. The narrow snout tapers to a point that protrudes somewhat from the disc. The eyes are immediately followed by the spiracles, which are of approximately equal size. There is a flap of skin between the nares with a weakly curved or lobed, fringed posterior margin; a pair of grooves run between this flap and the corners of the gently bow-shaped mouth. There are five

papilla Papilla (Latin, 'nipple') or papillae may refer to: In animals * Papilla (fish anatomy), in the mouth of fish * Papilla (worms), small bumps on the surface of certain worms * Basilar papilla, a sensory organ of lizards, amphibians and fish * ...

e in a row across the floor of the mouth. There are 24–41 upper tooth rows and 34–50 lower tooth rows. The blunt, ridged teeth are arranged into pavements with a

quincunx A quincunx ( ) is a geometry, geometric pattern consisting of five points arranged in a cross, with four of them forming a Square (geometry), square or rectangle and a fifth at its center. The same pattern has other names, including "in saltire" ...

pattern; those of adult males are longer than those of females, but are not pointed. 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 are short and triangular with their tips projecting slightly beyond the disc margin. The tail is broad and flattened at the base and becomes thin and whip-like past the (usually) single, slender stinging spine on the upper surface. Past the spine, there is a low dorsal keel and a well-developed ventral fin fold. There is a medium-sized oval pearl spine in the middle of the back; rays over across also gain a band of small, heart-shaped or flattened circular

s covering the median third of the disc, from between the eyes to the base of the tail. The tail is covered by small prickles behind the spine. It is a plain grayish brown above, and completely white below. The smallest West African stingray, this species grows to across and a weight of . The pearl stingray differs from the daisy stingray in being much smaller, and having a relatively smaller, oval pearl spine, more tooth rows, and fewer pectoral fin radials (113–127 versus 129–136).

Biology and ecology

Little is known of the natural history of the pearl stingray. Like other stingrays, it is

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

with females likely bearing litters of 1–3 pups.

Sexual maturation Sexual maturity is the capability of an organism to reproduce. In humans, it is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized as ...

occurs at a disc width of around .

Human interactions

Despite its small size, the pearl stingray is probably taken by "catch-all"

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 often p ...

operating in

coast A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...

al waters off

Senegal Senegal, officially the Republic of Senegal, is the westernmost country in West Africa, situated on the Atlantic Ocean coastline. It borders Mauritania to Mauritania–Senegal border, the north, Mali to Mali–Senegal border, the east, Guinea t ...

Ghana Ghana, officially the Republic of Ghana, is a country in West Africa. It is situated along the Gulf of Guinea and the Atlantic Ocean to the south, and shares borders with Côte d’Ivoire to the west, Burkina Faso to the north, and Togo to t ...

Côte d'Ivoire Ivory Coast, also known as Côte d'Ivoire and officially the Republic of Côte d'Ivoire, is a country on the southern coast of West Africa. Its capital city of Yamoussoukro is located in the centre of the country, while its largest city and ...

, and elsewhere, using longlines,

bottom trawl Bottom trawling is trawling (towing a trawl, which is a fishing net) along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and Demersal zone, demersal trawling. Benthic tra ...

s, and

trammel net A fishing net or fish net is a net used for fishing. Fishing nets work by serving as an improvised fish trap, and some are indeed rigged as traps (e.g. fyke nets). They are usually wide open when deployed (e.g. by casting or trawling), and th ...

s. However, no specific utilization data is available as it was and continues to be combined with the daisy stingray in catch records. The

(IUCN) has listed this species as Near Threatened. Given that the pearl stingray was once (and may still be) much more abundant than the daisy stingray, it likely comprised a majority of historically reported "daisy stingray" catches.

References

{{Taxonbar, from=Q28927548, from2=Q140863 Fontitrygon Fish described in 1984