sentences:  The genus has one of the widest distribution of any hypogean fish genus, with "P. sanguijuela" from the upper Amazon, some 2000 km from reported locations of "P. cisternarum" near the Amazon River mouth, and "P. dracunculus" also approximately 1900 km from the Rio Branco drainage area.This genus can be recognized by the combination of characteristics, such as their dorsal and anal fins being continuous with a rounded caudal fin, unbranched anal fin rays, a projecting lower jaw, bright red coloration, a lack of the dorsal fin spine locking mechanism, the first pectoral fin ray being soft instead of spinous.Most of these traits are rare or unusual among vast groups of catfish.