Author: (Müller & Henle, 1839)
FBname: Porcupine river stingray
Remark: Authorship controversial, but follows Rosa (1985a) in crediting original species name to Müller & Henle and not to d’Orbigny. Species later redescribed by Müller & Henle (1841) based on five additional specimens, but these do not have type status (the action of Castex, 1969, in designating a lectotype is therefore not valid; Rosa, 1985a). May be confused in the literature with <i>P. orbignyi</i> (occurrences in French Guiana, Guyana, Suriname, Venezuela). Reproductive biology unknown. Additional references: Bertin (1939), Castex (1965); Achenbach & Achenbach (1976), Compagno & Cook (1995).
Comments: Occurs in marshy zones where it is frequently found partially hidden in the sandy bottom.  This behavior, associated with its perfect immobility and its capacity to undergo homochromy, makes it practically undetectable to the eye.  Like all species of this family, <i>P. hystrix</i> has a tail which is equipped with one or more spines which fall spontaneously and are replaced 2 or 3 times a year.  At a length of 4 to 6 cm, the spine is a barbed, flattened skeletal formation inserted dorsally in the middle portion of the tail.  Its structure is similar to that of a tooth and appears as an ivory cone covered with enamel.  The spine is coated with an extremely toxic mucus produced by the cells of the skin and inflicts very painful wounds (Ref. 27188).