Urogymnus Müller & Henle, 1837

Last, Peter R., Naylor, Gavin J. P. & Manjaji-Matsumoto, B. Mabel, 2016, A revised classification of the family Dasyatidae (Chondrichthyes: Myliobatiformes) based on new morphological and molecular insights, Zootaxa 4139 (3), pp. 345-368 : 362-363

Genus Urogymnus Müller & Henle, 1837

Urogymnus Müller & Henle, 1837:434 . Type species Raja asperrima Bloch & Schneider, 1801 ; replacement name for Gymnura Müller & Henle, 1837 (preoccupied by Gymnura van Hasselt, 1823 ).

Definition. Large to gigantic dasyatids (adults to 1 00– 192 cm DW) characterised by the following: strongly depressed to robust, suboval to almost circular disc with pectoral-fin apex broadly rounded; snout angular to obtuse, rather short to very elongate (1.5–4.6 times combined orbit and spiracle length); eye very small to small and protruding; nasal curtain skirt shaped; mouth very narrow to narrow, with 3–7 oral papillae (absent in U.

lobistoma ); tail typically whip-like (but relatively short and stiff in U. asperrimus ), short to long (length 1–3.1 times DW), its base typically narrow and oval to almost circular in cross section; pelvic fins very small to small, almost entirely or fully concealed by disc; dorsal fold and ventral folds absent; caudal sting absent, or positioned normally or well back on tail (distance from pectoral-fin insertion to caudal-sting base 1.8–3.3 times interspiracular width); 1–3 mid-scapular thorns or thorns absent; no distinct shoulder thorn patch or median row on tail; denticle band well developed, its edge typically diffuse; skin elsewhere, often very rough or prickly (extremely so in U. asperrimus ); posterior tail with fine denticles or very prickly; dorsal surface plain or almost plain; ventral surface white, disc often dark edged; tail plain blackish or white, not banded; marine/estuarine/freshwater, Indo– West Pacific.

Species. U. asperrimus (Bloch & Schneider, 1801) , U. dalyensis ( Last & Manjaji-Matsumoto, 2008) , U. granulatus (Macleay, 1883) , U. lobistomus ( Manjaji-Matsumoto & Last, 2006) , U. polylepis (Bleeker, 1852) , and an undescribed species.

Remarks. Formerly monotypic, containing only the very spiny porcupine ray, Urogymnus asperrimus (Bloch & Schneider, 1801) . Molecular analysis confirms its placement in the Urogymninae ( Fig. 5). Five additional, large to very large species, including a new whipray from Australasia, were added to the group based on molecular data ( Fig. 3). These species all have a flexible, oval or subcircular disc, small or very small eyes, and relatively small pelvic fins. Some live in freshwater. An undescribed species occurs in inshore habitats of Australasia.