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.
Distribution and habitat
The western shovelnose stingaree is endemic to southwestern Australia, where it is one of the most common representatives of its family. Its range extends from the Gulf St Vincent near Glenelg westward to Perth, and possibly further north to Dongara. Bottom-dwelling in nature, the western shovelnose stingaree inhabits sandy and seagrass habitats at a depth of , and particularly favors relatively deeper waters close inshore. Individuals of all ages and both sexes occupy the same habitats year-round.
Description
The western shovelnose stingaree has a rounded pectoral fin disc slightly wider than long. The leading margins are nearly straight and converge at an obtuse angle on the fleshy snout, which has a blunt, non-protruding tip. The modestly sized eyes are followed by much larger, comma-shaped spiracles, whose "tails" curl down and forward to beneath the anterior third of the eyeball; the posterior margins of the spiracles are angular. The outer rims of the nostrils are expanded into large, flattened lobes. Between the nostrils is a skirt-shaped curtain of skin with a deeply fringed posterior margin that obscures the small mouth. The lower jaw bears a patch of papillae (nipple-shaped structures). There are 7–9 small papillae across the floor of the mouth. The teeth are small with roughly oval bases. The five pairs of gill slits are short.
The pelvic fins are small and rounded. The tail measures 71–91% of the disc length, has a flattened oval cross-section, and terminates in a low leaf-shaped caudal fin. The tail bears a serrated stinging spine on the dorsal surface about midway along its length; there are no dorsal fins or lateral fin folds. The skin is completely devoid of dermal denticles. The western shovelnose stingaree is grayish to ochre to dark brown in color above, becoming dusky to black on the caudal fin; some rays also exhibit an irregular scattering of lighter and darker spots. The underside is white to beige, occasionally with a wide, dark brown band and blotches along the margins of the disc and tail, which is most obvious in juveniles. This species has a maximum reported disc width of for males and for females.