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western shovelnose stingaree
The western shovelnose stingaree (''Trygonoptera mucosa'') is a common species of stingray in the family Urolophidae, inhabiting shallow sandy flats and seagrass beds off southwestern Australia from Perth to Gulf St Vincent. Growing to long, this small ray has a rounded pectoral fin disc and a blunt, broadly triangular snout. Its nostrils have enlarged lobes along the outer rims and a skirt-shaped curtain of skin between them with a strongly fringed posterior margin. Its tail ends in a lance-like caudal fin and lacks dorsal fins and lateral skin folds. This species is colored grayish to brownish above, sometimes with lighter and darker spots, and pale below, sometimes with darker marginal bands and blotches.
Sedentary polychaete worms are by far the most important food source of the western shovelnose stingaree; other benthic invertebrates and the odd bony fish may also be taken. Reproduction is aplacental viviparous, with females bearing one or two pups annually in late May or early June. The gestation period lasts one year, during which the mother produces histotroph ("uterine milk") to nourish her developing embryos. The International Union for Conservation of Nature (IUCN) has assessed this species as of Least Concern, as it faces little to no fishing pressure other than in the northwestern extreme of its range, where it is frequently caught incidentally by trawls. It usually survives to be discarded, though its tendency to abort its young when captured is of concern.
==Taxonomy==
Australian ichthyologist Gilbert Percy Whitley originally described the western shovelnose stingaree as ''Urolophus (Trygonoptera) mucosus'' in a 1939 volume of the scientific journal ''Australian Zoologist'', based on a specimen collected from King George Sound off Albany, Western Australia. Subsequent authors have recognized ''Trygonoptera'' as having full generic status. This species is closely related to the recently described ''T. galba'' and ''T. imitata'', with which it forms a species complex that may include additional undescribed species; one example is a form found off Perth that resembles ''T. mucosa'' but is much larger, reaching a length of . Other common names for this ray include kejetuk, bebil, and western stingaree.
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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