The blackish stingray, ''Hemitrygon navarrae'', is a little-known
species of
stingray
Stingrays are a group of sea rays, which are cartilaginous fish related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatidae ( ...
in the
family Dasyatidae, found in the northwestern
Pacific Ocean off the coasts of
mainland China and
Taiwan. This species reaches across and has a chocolate brown, diamond-shaped
pectoral fin disc nearly as long as wide. Its whip-like tail bears three large
tubercles in front of the stinging spine, as well as both
dorsal and ventral fin folds with the ventral fold half as long as the disc. Caught as
bycatch
Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...
in
bottom trawls, the blackish stingray is frequently marketed as food in
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
. T
Taxonomy
Austrian
zoologist Franz Steindachner
Franz Steindachner (11 November 1834 in Vienna – 10 December 1919 in Vienna) was an Austrian Zoology, zoologist, ichthyologist, and herpetologist. He published over 200 papers on fishes and over 50 papers on reptiles and amphibians. Steindachne ...
originally described the blackish stingray as ''Trygon navarrae'', in an 1892 volume of the
scientific journal
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research.
Content
Articles in scientific journals are mostly written by active scientists such as s ...
''Denkschriften der Mathematisch-Naturwissenschaftlichen Classe der Kaiserlichen Akademie der Wissenschaften in Wien''.
The
type specimen is a male across, collected from
Shanghai, China.
[Nishida, K. and K. Nakaya (1990). "Taxonomy of the genus ''Dasyatis'' (Elasmobranchii, Dasyatididae) from the North Pacific." in Pratt, H.L., S.H. Gruber and T. Taniuchi. ''Elasmobranchs as living resources: advances in the biology, ecology, systematics, and behaviour, and the status of fisheries.'' NOAA Technical Report, NMFS 90. pp. 327–346.]
Distribution and habitat
The blackish stingray is found in the
Yellow,
Bohai Bohai may refer to:
* Bohai Sea, or Bo Hai, the innermost gulf of the Yellow Sea
* Balhae, known as Bohai in Chinese, a former mixed Mohe-Goguryeo empire which existed from 698 to 926 in Manchuria
Locations or areas in China
* Bohai Bay, one of t ...
, and
East China Sea
The East China Sea is an arm of the Western Pacific Ocean, located directly offshore from East China. It covers an area of roughly . The sea’s northern extension between mainland China and the Korean Peninsula is the Yellow Sea, separated b ...
s, to as far south as Taiwan. This
bottom-dwelling
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning ...
species is found in coastal waters, and has been recorded from the
estuary of the
Yellow River.
Description
The blackish stingray has a diamond-shaped
pectoral fin disc almost as long as wide, with slightly sinuous leading margins, narrowly rounded outer corners, and almost straight trailing margins. The triangular, projecting snout comprises about one-fourth the disc length and bears 2–3 rows of enlarged pores along the midline. The eyes are small and closely followed by a pair of larger
spiracle Spiracle or spiraculum may refer to:
* Spiracle (arthropods), opening in the exoskeletons of some arthropods
* Spiracle (vertebrates), openings on the surface of some vertebrates
* Spiraculum, a genus of land snails in family Cyclophoridae
Cycl ...
s. The mouth is bow-shaped, with three
papillae across the floor. There are 40 upper tooth rows and 37 lower tooth rows; the teeth of adult males are pointed while those of juveniles and females are blunt.
The tail is whip-like and bears a stinging spine on the dorsal surface, as well as both upper and lower fin folds; the ventral fold measures half the disc length. There are 4–6 rows of small tubercles between the eyes, a narrow strip of tubercles running down the center of back to the base of the tail, and three enlarged tubercles in front of the tail spine. The coloration is a plain dark brown above and whitish below.
This species attains a disc width of and a total length of
Biology and ecology
Little is known of the natural history of the blackish stingray.
Known
parasites of this species include the
copepod
Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...
''Caligus dasyaticus'' and the
monogenean ''Heterocotyle chinensis''.
It is presumably
aplacental viviparous like other members of its family.
Human interactions
Many blackish stingrays are
captured incidentally by
commercial bottom trawlers off the Chinese coast. It is one of the three most common stingray species sold for human consumption in China, though it is not highly valued.
The blackish stingray is subject to intense fishing pressure within its range, and
habitat degradation from coastal development may pose an additional threat. The
International Union for Conservation of Nature (IUCN) has assessed this species as vulnerable.
References
{{Taxonbar, from=Q138562
Hemitrygon
Taxa named by Franz Steindachner
Fish described in 1892