Urogymnus acanthobothrium Last, White & Kyne, 2016
Mumburarr whipray

Family:  Dasyatidae (Stingrays), subfamily: Urogymninae
Max. size:  103 cm WD (male/unsexed); 161 cm WD (female)
Environment:  benthopelagic; brackish; marine; depth range 2 - 20 m
Distribution:  Western Pacific: western Australia and Papua New Guinea.
Diagnosis:  This species is distinguished by the following set of characters: elongate disc suboval with the snout tip to axis of maximum width 53% DW; anterior disc margin not truncated, it is almost straight with lateral apices broadly rounded; preorbital snout broadly angular, its angle 114° and with a very small apical lobe; preorbit long, its length 26% TL, 2.1 times interorbital length; orbits are small and protruded slightly; spiracle is very large, 8.6% DW, 1.9 in orbit diameter; internasal distance is 2.0 in prenasal length, 2.8 times nostril length; preoral snout length is 2.6 times mouth width, 2.5 times internarial distance; caudal sting very large with its length more than a 30% DW; mid-scapular denticles are very small and inconspicuous; secondary denticles are very small, rather widely spaced, band delimited but margin not sharply defined, band truncate forward of eye; presence of minute upright tertiary denticles, barely visible; with a low and short-based ventral tail fold; dorsal disc colour is variable, juveniles plain dark greyish brown to yellowish brown, while in adults very finely and faintly mottled greyish white to yellowish brown; its ventral surface is largely white, posterior disc without regular dark margins; tail beyond sting white in young, while in adults it is unknown but possibly paler than anterior tail; propterygial radials 66, 3 times the number of mesopterygial radials; 151 total vertebral segments (excluding synarcual) (Ref. 110274).
Biology:  Juveniles were recorded from lower reaches of rivers at depths of 2.2-8.7 m; salinity 14.6-33.1; turbidity 367->1000 NTU. Subadult specimens were from depths of 10-20 m. An adult female (161.0 cm DW, 174.0 cm disc length) aborted a late embryo which was estimated to be ca. 26.5 cm DW on capture. Juveniles (5) measured 39.o - 67.2 cm DW, 43.0-72.0 cm DL, while a late adolescent male measured 103.0 cm DW, This stingray could be traditionally hunted for food and the caudal sting can be used as a traditional knife. (Ref. 110274).
IUCN Red List Status: Data deficient (DD); Date assessed: 22 April 2021 Ref. (130435)
Threat to humans:  harmless


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