Urotrygonidae is a family of rays

Batoidea

Batoidea is a superorder of cartilaginous fish commonly known as rays and skates, containing more than 500 described species in thirteen families...

 in the order Myliobatiformes

Myliobatiformes

Myliobatiformes is one of the four orders of batoids, cartilaginous fishes related to sharks. They were formerly included in the order Rajiformes, but more recent phylogenetic studies have shown that the myliobatiforms are a monophyletic group, and that its more derived members evolved their...

, commonly referred to as the American round stingrays or round rays. They are native to the tropical and warm temperate

Temperate

In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...

 marine waters of the Americas

Americas

The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...

. The two genera

Genera

Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...

 in this family were formerly placed within the family Urolophidae, whose species are now restricted to the Indo-Pacific

Indo-Pacific

The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...

. They have a round pectoral fin disk, a slender tail

Tail

The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds...

 with a caudal fin, no dorsal fin

Dorsal fin

A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

s, and a venom

Venom

Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...

ous tail spine.

Urobatis

• Urobatis concentricus R. C. Osburn & Nichols
  John Treadwell Nichols
  John Treadwell Nichols was an American ichthyologist.-Biography:Nichols was born as son of John White Treadwell Nichols in Jamaica Plain, Boston, Massachusetts. In 1906 he studied vertebrate zoology at Harvard College where he graduated to Bachelor of Arts...
  
  , 1916 (Spot-on-spot round ray)
• Urobatis halleri (J. G. Cooper
  James Graham Cooper
  James Graham Cooper was an American surgeon and naturalist.Cooper was born in New York. He worked for the California Geological Survey with Josiah Dwight Whitney, William Henry Brewer and Henry Nicholas Bolander...
  
  , 1863) (Haller's round ray)
• Urobatis jamaicensis (Cuvier
  Georges Cuvier
  Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...
  
  , 1816) (Yellow stingray)
• Urobatis maculatus Garman, 1913 (Spotted round ray)
• Urobatis marmoratus (Philippi {Krumweide}
  Rodolfo Amando Philippi
  Rodolfo Amando Philippi was a German-Chilean paleontologist and zoologist....
  
  , 1893) (Chilean round stingray)
• Urobatis tumbesensis (Chirichigno F. & McEachran, 1979) (Tumbes round stingray)

Urotrygon

• Urotrygon aspidura (D. S. Jordan
  David Starr Jordan
  David Starr Jordan, Ph.D., LL.D. was a leading eugenicist, ichthyologist, educator and peace activist. He was president of Indiana University and Stanford University.-Early life and education:...
  
   & C. H. Gilbert
  Charles Henry Gilbert
  Charles Henry Gilbert was a pioneer ichthyologist and fishery biologist of particular significance to natural history of the western United States. He collected and studied fishes from Central America north to Alaska and described many new species...
  
  , 1882) (Spiny-tail round ray)
• Urotrygon caudispinosus Hildebrand, 1946
• Urotrygon chilensis (Günther, 1872) (Chilean round ray)
• Urotrygon cimar López S. & Bussing, 1998
• Urotrygon microphthalmum Delsman, 1941 (Smalleyed round stingray)
• Urotrygon munda Gill
  Theodore Gill
  Theodore Nicholas Gill was an American ichthyologist, mammalogist, malacologist and librarian.Born and educated in New York City under private tutors, Gill early showed interest in natural history. He was associated with J...
  
  , 1863 (Munda round ray)
• Urotrygon nana Miyake & McEachran, 1988 (Dwarf round ray)
• Urotrygon peruanus Hildebrand, 1946 (Peruvian stingray)
• Urotrygon reticulata Miyake & McEachran, 1988 (Reticulate round ray)
• Urotrygon rogersi (D. S. Jordan
  David Starr Jordan
  David Starr Jordan, Ph.D., LL.D. was a leading eugenicist, ichthyologist, educator and peace activist. He was president of Indiana University and Stanford University.-Early life and education:...
  
   & Starks
  Edwin Chapin Starks
  Edwin Chapin Starks was an ichthyologist most associated with Stanford University. He was known as an authority on the osteology of fish. He also did studies of fish of the Puget Sound. Additionally his wife and daughter were both involved in either science or natural history....
  
  , 1895) (Roger's round ray)
• Urotrygon serrula Hildebrand, 1946
• Urotrygon simulatrix Miyake & McEachran, 1988 (Fake round ray)
• Urotrygon venezuelae L. P. Schultz, 1949 (Venezuela round stingray)