Tubemouth whipray
| Tubemouth whipray | |
|---|---|
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Superorder: | Batoidea |
| Order: | Myliobatiformes |
| Family: | Dasyatidae |
| Genus: | Urogymnus |
| Species: | U. lobistoma
|
| Binomial name | |
| Urogymnus lobistoma | |
| Synonyms | |
| |
The tubemouth whipray (Urogymnus lobistoma) is a little-known
fisheries. The International Union for Conservation of Nature (IUCN) has listed it as Vulnerable
.
Taxonomy
The first known specimens of the tubemouth whipray were caught from the
Distribution and habitat
The tubemouth whipray has only been found in the South China Sea off southern Sumatra and southwestern Borneo, to as far north as Bintulu. It is associated with the runoff from large rivers and mangrove forests, occurring in brackish water under 30 m (98 ft) deep over muddy bottoms.[1]
Description
The tubemouth whipray has a diamond-shaped
pectoral fin disc longer than wide, with broadly rounded outer corners. The anterior margins of the disc are strongly concave, and converge on a narrow, flattened, pointed snout. The eyes are tiny, and followed by much larger, teardrop-shaped spiracles. The nostrils are small, with a narrow, nearly rectangular flap of skin between them. The mouth is straight and transverse, and contains no papillae (nipple-like structures). The jaws are highly protrusible, capable of forming a tube longer than the mouth width; this trait is unique within the 'uarnacoides' complex.[3] There are 29–34 upper and 31–36 lower tooth rows; the teeth are small, conical, and blunt, and densely arranged into pavement-like surfaces. There is no sexual dimorphism in tooth shape.[3]
The
dermal denticles, with slightly larger plate-like denticles forming a distinct, broad band extending from before the eyes to the base of the tail; this denticle band is present at birth. There are also 1–5 enlarged, oval denticles in a row between the "shoulders". This species is uniform grayish to light brown above, with the eyes and spiracles rimmed in white, and uniform white below. Females grow up to 1 m (3.3 ft) across, while males are smaller.[3]
Biology and ecology
The diet of the tubemouth whipray likely consists of
aplacental viviparous with the developing embryos nourished by maternally produced histotroph ("uterine milk"). One known specimen contained a single near-term pup measuring 18 cm (7.1 in) across. Males attain sexual maturity at under 49 cm (19 in) across, and females at under 70 cm (28 in) across.[3]
Human interactions
The tubemouth whipray remains fairly common within its restricted range, particularly off Sarawak. However, its population has likely declined significantly over the past few decades due to extensive
trawl and bottom longline fisheries that take it for meat. As a result, the International Union for Conservation of Nature (IUCN) has assessed this species as Vulnerable.[1][5]
References
- ^ doi:10.2305/IUCN.UK.2020-3.RLTS.T161546A124504854.en. Retrieved 20 November 2021.)
{{cite journal}}: CS1 maint: multiple names: authors list (link - ^ Froese, Rainer; Pauly, Daniel (eds.) (2018). "Urogymnus lobistoma" in FishBase. October 2018 version.
- ^ S2CID 22873832.
- ^ Froese, Rainer and Pauly, Daniel, eds. (2018). Species of Urogymnus in FishBase. October 2018 version.
- ^ ISBN 978-1-921605-59-8.