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longtail butterfly ray
The longtail butterfly ray (''Gymnura poecilura'') is a species of butterfly ray, family Gymnuridae, native to the Indo-Pacific from the Red Sea to southern Japan and western Indonesia. Growing up to across, this ray has a lozenge-shaped pectoral fin disc about twice as wide as long, colored brown to gray above with many small, light spots. The spiracles behind its eyes have smooth rims. This species can be identified by its tail, which is about as long as the snout-to-vent distance, lacks fins, and bears nine to twelve each of alternating black and white bands.
Bottom-dwelling in nature, the longtail butterfly ray frequents sandy or muddy habitats in coastal waters shallower than . Its diet consists of bony fishes, molluscs, and crustaceans. This species gives birth to live young; the developing embryos are nourished first by yolk and later by histotroph ("uterine milk") supplied by its mother. There is no defined breeding season, and females bear litters of up to seven pups. Used for its meat, the longtail butterfly ray is often caught by artisanal and commercial fisheries. The International Union for Conservation of Nature (IUCN) has listed this species as Near Threatened, citing the high levels of fishing pressure within its range and its low reproductive rate.
==Taxonomy and phylogeny==
The longtail butterfly ray was originally described as ''Raja poecilura'' by English zoologist George Shaw, in his 1804 ''General Zoology or Systematic Natural History''. He did not designate a type specimen as his account was based on an illustration by Scottish naturalist Patrick Russell, published a year earlier in ''Descriptions and Figures of Two Hundred Fishes Collected at Vizagapatam on the Coast of Coromandel''. The specific epithet ''poecilura'' is derived from the Greek ''poikilos'' ("of many colors") and ''oura'' ("tail"). Later authors moved this species to the genus ''Gymnura''.〔〔〔
Further research is needed to determine whether the isolated longtail butterfly rays in French Polynesia are in fact the same species as those from the rest of its range.〔 Phylogenetic studies based on morphology and mitochondrial DNA indicate that the longtail butterfly ray is closely related to the zonetail butterfly ray (''G. zonura''), which shares much of its range in the Indo-Pacific.〔〔 Another name for the longtail butterfly ray is variegated butterfly ray.〔
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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