American zoologist Samuel Garman published the original description of the longtail stingray in an 1880 issue of the scientific journal Bulletin of the Museum of Comparative Zoology.

He gave it the name Trygon longa, in reference to the long tail, and designated a specimen from Acapulco, Mexico and another from Panama as the syntypes.

[1] Apparently solitary in nature, the longtail stingray is a predator of bottom-dwelling bony fishes and invertebrates, in particular stomatopods, decapods, and molluscs.

[6][9] Known parasites of this species include the tapeworms Acanthobothrium cimari, A. cleofanus, A. costarricense, A. puntarenasense, and A. vargasi,[10][11] Anthocephalum lukei and A. michaeli,[12] Parachristianella dimegacantha,[13] Pseudochristianella elegantissima and P. nudiscula,[14] and Pterobothrioides carvajali,[15] and the monogenean Listrocephalos whittingtoni.

Near-term females appear to swim into shallow estuaries and tidal creeks to give birth, following a gestation period of 10–11 months, and may mate again immediately after.

[17] This species is likely landed by inshore fisheries targeting shark and ray throughout Central America; it is caught by bottom trawls and longlines, and is especially susceptible to gillnets as its tail spine easily becomes entangled in the mesh.

The impact of fishing on its population is unknown, as fishery landings in the region are poorly monitored and the longtail stingray is not reported separately from other ray species.

The International Union for Conservation of Nature (IUCN) has listed this species as vulnerable, while noting that its slow reproductive rate would limit its capacity to recover from over-exploitation.