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pearl stingray
The pearl stingray (''Dasyatis margaritella'') is a little-known species of stingray in the family Dasyatidae, found in shallow coastal waters from Mauritania to Angola. Growing to 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, nacreous 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.
==Taxonomy and phylogeny==
Prior to being described by Leonard Compagno 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 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.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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