''Pristimantis vilarsi'', also known as the Rio Uaupes robber frog, is a species of

frog A frog is any member of a diverse and largely Carnivore, carnivorous group of short-bodied, tailless amphibians composing the order (biology), order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-f ...

in the family

Strabomantidae The Strabomantidae are a family of frogs native to South America. These frogs lack a free-living larval stage and hatch directly into miniature "froglets". This family includes ''Pristimantis'', the most speciose genus of any vertebrate. System ...

. It is found in the upper

Amazon basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Bolivi ...

in Brazil, Peru, Colombia, and Venezuela.

Description

Adult males measure and adult females in

snout–vent length Snout–vent length (SVL) is a morphometric measurement taken in herpetology from the tip of the snout to the most posterior opening of the cloacal slit (vent)."direct line distance from tip of snout to posterior margin of vent" It is the most c ...

. Dorsal skin is shagreened and has scattered small warts, but ventral skin smooth. The tympanum is prominent and vertically oval. The snout is subacuminate to acuminate in dorsal view, but round in vertical profile. The

canthus rostralis In snakes and amphibians, the canthus, canthal ridge or ''canthus rostralis'',Spawls S, Branch B. 1995. ''The Dangerous Snakes of Africa''. Ralph Curtis Books. Dubai: Oriental Press. 192 pp. . is the angle between the flat crown of the head and the ...

is distinct and angular. Fingers and toes bear discs (enlarged on fingers III and IV and toes IV and V) but have no webbing. Males have vocal slits. There are three color patterns: (1) dorsum greenish gray, light to dark brown, without pattern or with very small black spots, (2) strongly patterned dorsum with brown to olive background and bearing a "W" mark between the shoulders, as well as diagonal dark brown stripes across the body and limbs, and (3) an intermediate form showing light to dark brown dorsum with indistinct bars, with or without the W between the shoulders, and sometimes with a lichen-like pattern. All forms have dark brown canthal and supratympanic stripes.

Habitat and conservation

''Pristimantis vilarsi'' lives in the leaf litter of lowland rainforests at elevations of

above sea level Height above mean sea level is a measure of the vertical distance (height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as ''orthometric heights''. The comb ...

( in Colombia). During the night they can be found on low plants, leaves, rocks, mossy walls, and on the ground. Males call at night. The egg deposition site is unknown. It appears to tolerate some disturbance of its habitat. It is a common species whose range overlaps with several protected areas.

References

{{Taxonbar, from=Q4454615 vilarsi Frogs of Brazil Amphibians of Colombia Frogs of Peru Amphibians of Venezuela Amphibians described in 1941 Taxonomy articles created by Polbot