Pearl stingray
Encyclopedia
The pearl stingray is a little-known species
of stingray
in the family
Dasyatidae, found in shallow coastal waters from Mauritania
to Angola
. Growing to 30 cm (11.8 in) across, this species has a rounded pectoral fin disc with a pointed snout, and a wide band of dermal denticles over the back in adults. It closely resembles and is often confused for the much larger daisy stingray
(D. margarita); both species are characterized by the presence of an enlarged, nacre
ous denticle in the middle of the back called a "pearl spine". The International Union for Conservation of Nature (IUCN) does not yet have enough information to assess the pearl stingray's conservation status
, but it is likely that most of the historically reported fishery
catches of the daisy stingray were in fact of this species.
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, though its existence had been recognized since at least 1965. The specific epithet margaritella comes from the diminutive of the Latin
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 is a male 19 cm (7.5 in) across, from Mbode, Cameroon
.
In appearance, the pearl stingray resembles the daisy stingray
and the Niger stingray
(D. garouaensis), both also native to West Africa
, suggesting that the three species are closely related.. Lisa Rosenberger's 2001 phylogenetic analysis, based on morphology
, found that the pearl stingray is the sister species of the sharpnose stingray (Himantura gerrardi), and that the two form a clade
with the pale-edged stingray
(D. zugei) and the smooth butterfly ray
(Gymnura micrura). These results support the growing consensus that neither Dasyatis nor Himantura
are monophyletic. The daisy and Niger stingrays were not included in the study.
, from Cape Blanc in Mauritania
to Angola
. This bottom-dwelling species inhabits shallow, coastal marine
and brackish water
s, and has been reported from lagoon
s and estuaries, including the mouth of the Congo River
.
s, 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
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
pattern; those of adult males are longer than those of females, but are not pointed. The pelvic fins 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 13–14 cm (5.1–5.5 in) across also gain a band of small, heart-shaped or flattened circular dermal denticles 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 30 cm (11.8 in) across and a weight of 1 kg (2.2 lb). 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).
operating in coast
al waters off Senegal
, Ghana
, Côte d'Ivoire
, and elsewhere, using longlines, bottom trawls, and trammel nets. However, no specific utilization data is available as it was and continues to be combined with the daisy stingray in catch records. As a result, the International Union for Conservation of Nature (IUCN) has listed this species as Data Deficient
. 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.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of stingray
Myliobatiformes
Myliobatiformes is one of the four orders of batoids, cartilaginous fishes related to sharks. They were formerly included in the order Rajiformes, but more recent phylogenetic studies have shown that the myliobatiforms are a monophyletic group, and that its more derived members evolved their...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Dasyatidae, found in shallow coastal waters from Mauritania
Mauritania
Mauritania is a country in the Maghreb and West Africa. It is bordered by the Atlantic Ocean in the west, by Western Sahara in the north, by Algeria in the northeast, by Mali in the east and southeast, and by Senegal in the southwest...
to Angola
Angola
Angola, officially the Republic of Angola , is a country in south-central Africa bordered by Namibia on the south, the Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean with Luanda as its capital city...
. Growing to 30 cm (11.8 in) across, this species has a rounded pectoral fin disc with a pointed snout, and a wide band of dermal denticles over the back in adults. It closely resembles and is often confused for the much larger daisy stingray
Daisy stingray
The daisy stingray, Dasyatis margarita, is a little-known species of stingray in the family Dasyatidae, found in shallow coastal waters along the coast of West Africa. This species typically grows to across and has a rounded pectoral fin disc and a wide band of dermal denticles over its back...
(D. margarita); both species are characterized by the presence of an enlarged, nacre
Nacre
Nacre , also known as mother of pearl, is an organic-inorganic composite material produced by some mollusks as an inner shell layer; it is also what makes up pearls. It is very strong, resilient, and iridescent....
ous denticle in the middle of the back called a "pearl spine". The International Union for Conservation of Nature (IUCN) does not yet have enough information to assess the pearl stingray's conservation status
Conservation status
The conservation status of a group of organisms indicates whether the group is still extant and how likely the group is to become extinct in the near future...
, but it is likely that most of the historically reported fishery
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
catches of the daisy stingray were in fact of this species.
Taxonomy and phylogeny
Prior to being described by Leonard CompagnoLeonard Compagno
Leonard Joseph Victor Compagno is 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 Agriculture Organization of the United Nations.-Career:*Ph.D,...
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, though its existence had been recognized since at least 1965. The specific epithet margaritella comes from the diminutive of the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
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 is a male 19 cm (7.5 in) across, from Mbode, Cameroon
Cameroon
Cameroon, officially the Republic of Cameroon , is a country in west Central Africa. It is bordered by Nigeria to the west; Chad to the northeast; the Central African Republic to the east; and Equatorial Guinea, Gabon, and the Republic of the Congo to the south. Cameroon's coastline lies on the...
.
In appearance, the pearl stingray resembles the daisy stingray
Daisy stingray
The daisy stingray, Dasyatis margarita, is a little-known species of stingray in the family Dasyatidae, found in shallow coastal waters along the coast of West Africa. This species typically grows to across and has a rounded pectoral fin disc and a wide band of dermal denticles over its back...
and the Niger stingray
Niger stingray
The Niger stingray or smooth freshwater stingray, Dasyatis 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, almost circular pectoral fin disk, slightly projecting snout...
(D. garouaensis), both also native to West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...
, suggesting that the three species are closely related.. Lisa Rosenberger's 2001 phylogenetic analysis, based on morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
, found that the pearl stingray is the sister species of the sharpnose stingray (Himantura gerrardi), and that the two form a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
with the pale-edged stingray
Pale-edged stingray
The pale-edged stingray or sharpnose stingray is a species of stingray in the family Dasyatidae, found in the Indian and Pacific Oceans from India to the western Malay Archipelago and southern Japan. This bottom-dwelling ray is most commonly found over sandy areas shallower than , as well as in...
(D. zugei) and the smooth butterfly ray
Smooth butterfly ray
The smooth butterfly ray is a species of fish in the Gymnuridae family. It is found in Belize, Brazil, Cameroon, Colombia, the Democratic Republic of the Congo, Costa Rica, French Guiana, Gambia, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Senegal, Sierra Leone, Suriname, Trinidad and...
(Gymnura micrura). These results support the growing consensus that neither Dasyatis nor Himantura
Himantura
Himantura is a genus of stingray in the family Dasyatidae, commonly known as the whiprays. They are distinguished from other stingrays by a long, slender tail without tail folds. Himantura species are very morphologically diverse and the genus may be polyphyletic...
are monophyletic. The daisy and Niger stingrays were not included in the study.
Distribution and habitat
The pearl stingray is found along the western coast of AfricaAfrica
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, from Cape Blanc in Mauritania
Mauritania
Mauritania is a country in the Maghreb and West Africa. It is bordered by the Atlantic Ocean in the west, by Western Sahara in the north, by Algeria in the northeast, by Mali in the east and southeast, and by Senegal in the southwest...
to Angola
Angola
Angola, officially the Republic of Angola , is a country in south-central Africa bordered by Namibia on the south, the Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean with Luanda as its capital city...
. This bottom-dwelling species inhabits shallow, coastal marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
and brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
s, and has been reported from lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
s and estuaries, including the mouth of the Congo River
Congo River
The Congo River is a river in Africa, and is the deepest river in the world, with measured depths in excess of . It is the second largest river in the world by volume of water discharged, though it has only one-fifth the volume of the world's largest river, the Amazon...
.
Description
The pearl stingray has a moderately thin, oval-shaped pectoral fin 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 spiracleSpiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s, 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 (fish mouth structure)
The papilla, in certain kinds of fish, particularly rays, sharks, and catfish, are small lumps of dermal tissue found in the mouth, where they are "distributed uniformly on the tongue, palate, and pharynx"...
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
Quincunx
A quincunx is a geometric pattern consisting of five points arranged in a cross, that is five coplanar points, four of them forming a square or rectangle and a fifth at its center...
pattern; those of adult males are longer than those of females, but are not pointed. The pelvic fins 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 13–14 cm (5.1–5.5 in) across also gain a band of small, heart-shaped or flattened circular dermal denticles 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 30 cm (11.8 in) across and a weight of 1 kg (2.2 lb). 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 with females likely bearing litters of 1–3 pups. Sexual maturation occurs at a disc width of around 20 cm (7.9 in).Human interactions
Despite its small size, the pearl stingray is probably taken by "catch-all" commercial fisheriesCommercial fishing
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 pursue fish far into the ocean under adverse conditions...
operating in coast
Coast
A coastline or seashore is the area where land meets the sea or ocean. A precise line that can be called a coastline cannot be determined due to the dynamic nature of tides. The term "coastal zone" can be used instead, which is a spatial zone where interaction of the sea and land processes occurs...
al waters off Senegal
Senegal
Senegal , officially the Republic of Senegal , is a country in western Africa. It owes its name to the Sénégal River that borders it to the east and north...
, Ghana
Ghana
Ghana , officially the Republic of Ghana, is a country located in West Africa. It is bordered by Côte d'Ivoire to the west, Burkina Faso to the north, Togo to the east, and the Gulf of Guinea to the south...
, Côte d'Ivoire
Côte d'Ivoire
The Republic of Côte d'Ivoire or Ivory Coast is a country in West Africa. It has an area of , and borders the countries Liberia, Guinea, Mali, Burkina Faso and Ghana; its southern boundary is along the Gulf of Guinea. The country's population was 15,366,672 in 1998 and was estimated to be...
, and elsewhere, using longlines, bottom trawls, and trammel nets. However, no specific utilization data is available as it was and continues to be combined with the daisy stingray in catch records. As a result, the International Union for Conservation of Nature (IUCN) has listed this species as Data Deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
. 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.