A new species of forest snake of the genus Rhadinaea from Tropical Montane Rainforest in the Sierra Madre del Sur of Oaxaca, Mexico (Squamata, Dipsadidae)

Content of the dipsadid genus has changed considerably since Myers' 1974 revision. Three species groups are recognized currently in the genus. Our fieldwork in Oaxaca in June 2018 produced a single specimen of considered to represent a new taxon. This new species is described from converted Premontane Wet Forest in the municipality of Santa Catarina Juquila in the Sierra Madre del Sur of southern Oaxaca, Mexico. It is most closely related to , from which it can be distinguished easily by color pattern and scutellation, and represents a species group distinct from the other three occupying the genus.