Fluvitrygon, Last, Peter R., Naylor, Gavin J. P. & Manjaji-Matsumoto, B. Mabel, 2016

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 : 360

Genus Fluvitrygon gen. nov.

Type species Himantura signifer Compagno & Roberts, 1982 ; newly proposed.

Definition. Small dasyatids (adults typically to ~ 37 cm DW) characterised by the following: depressed, oval to almost circular disc with pectoral-fin apex broadly rounded; snout acutely angular to obtuse, short or long (2.2–3.7 times combined orbit and spiracle length); eye very small or small and protruding slightly; nasal curtain broadly skirt shaped; mouth narrow to medium-sized with 2–8 oral papillae; tail rather short or long, whip-like (length 1.3– 3.8 times DW), its base narrow and oval to almost circular in cross section; pelvic fins medium-sized, almost entirely concealed by disc; dorsal fold and ventral folds absent; caudal sting rather forward on tail (distance from pectoral-fin insertion to caudal-sting base 2.3–3.2 times interspiracular width); 0–2 pearl-shaped mid-scapular thorns, no other scapular thorns; denticle band well developed with edge diffuse to sharply defined, skin on rest of disc typically naked; median thorns on tail weak or absent, small denticles usually on posterior tail in adults; dorsal coloration plain or with strong pattern; ventral surface white, disc margin sometimes dark edged; posterior tail plain or with pattern; estuarine/freshwater, Indo–Malay Archipelago.

Etymology. Combination of the Latin fluvius (river) and Greek trygon (stingray) reflects the riverine distribution of all members of the genus.

Species. F. kittipongi (Vidthayanon & Roberts, 2006) , F. oxyrhyncha (Sauvage, 1878) , and F. signifer ( Compagno & Roberts, 1982) .

Remarks. Newly erected, morphologically similar genus consisting of three small species previously placed in Himantura . These freshwater/estuarine species are sister to Brevitrygon ( Fig. 3), but differ in tail morphology from members of that marine group (having a longer, narrower-based, whip-like tail).