Fontitrygon, 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 : 360-361

Genus Fontitrygon gen. nov.

Type species Trygon margarita Günther, 1870 ; newly proposed.

Definition. Heterogeneous group of small to large dasyatids (adults 28–165 cm DW) characterised by the following: variably depressed, oval to almost circular disc (weakly rhombic in F. c o l a ren s i s) with pectoral-fin apex broadly rounded; snout acutely angular to obtuse, long to very long (1.8–4 times combined orbit and spiracle length); eye very small or small and sunken to protruding slightly; nasal curtain skirt-shaped to bilobed; mouth narrow to very narrow with 1–5 oral papillae; tail rather short or long, whip-like (length 1.5–3.8 times DW), its base narrow and oval to almost circular in cross section; pelvic fins small to medium-sized, almost entirely concealed by disc (except long, pointed and well exposed in F. g e i j s k es i); dorsal fold reduced to a ridge or absent; ventral fold low or very low, short to long based; caudal sting not positioned well back on tail (distance from pectoral-fin insertion to caudal-sting base 1.9–3 times interspiracular width); 1–4 mid-scapular thorns or thorns on nape in a row; small scapular thorns present; denticle band well developed with edge diffuse to sharply defined, skin on rest of disc prickly or with patchy denticles; median thorns on tail either continuous with those of mid-disc or absent; rest of tail naked or spiny; dorsal coloration plain; ventral surface white, disc margin sometimes dark edged; posterior tail typically plain; marine/estuarine/freshwater, western Africa and Atlantic Ocean.

Etymology. Combination of the Latin fontis (spring, fountain) and Greek trygon (stingray) reflects an ability of these stingrays to live in estuaries and freshwater.

Species. F. c o l a re ns i s (Santos, Gomes & Charvet-Almeida, 2004), F. garouaensis (Stauch & Blanc, 1962) , F. geijskesi (Boeseman, 1948) , F. margarita (Günther, 1870) , F. margaritella (Compagno & Roberts, 1984) , and F. ukpam (Smith, 1863) .

Remarks. Newly erected, morphologically heterogeneous genus consisting of six small to large stingrays, with two species confined to freshwater and the others to estuarine/marine habitats. The tail is long and whip-like (typical of the Urogymninae), but has a well-developed ventral skin fold so they have been traditionally placed in the genus Dasyatis . Fontitrygon margarita and F. margaritella are assigned in this group based on molecular data ( Fig. 3), but placement of the other three species is provisional in the absence of sequence data. The four species from western Africa form a natural group based on morphology. However, the two western Atlantic species, F. colarensis and F. geijskesi , differ significantly from the other taxa (a much more elongated, narrowly pointed snout, smaller and somewhat sunken eyes, and pelvic fins longer and protruding further beyond the disc margin), and may prove to be non-congeneric with the African species. More data is needed for this group.