Cochranella erminea Torres-Gastello, Suárez-Segovia & Cisneros-Heredia 2007

Rulyrana erminea is known from a single adult female specimen, measuring 23.6mm in SVL. This species can be distinguished from all other centrolenids by the following three characters in combination: (1) strong webbing between finger III and finger IV; (2) visceral peritonea lacking white pigment; (3) distinctive viridian to olive green dorsal coloration plus numerous white enameled spots and sparse dark blue spots on flat warts. This species also has: (1) a slightly elongated head, though still wider than the body; (2) short, rounded snout, slightly sloping anteroventrally in profile; nostrils slightly elevated; canthus rostralis indistinct, with shallow platform in between; choanae small, elliptical, widely separated (3) lips slightly flared (4) vomerine teeth present, four on each side (5) tongue elongate, ovoid (6) eyes large, oriented anterolaterally, diameter larger than width of finger III disc, also wider than concave interorbital region (6) tympanum ovoid, positioned dorsolaterally, slight incline in dorsal view; tympanic annulus present; supratympanic fold indistinct; (7) finger I longer than finger II; (8) prepollex enlarged but concealed; (9) webbing absent between fingers I and II, basal between fingers II and III, extensive between fingers III and IV; fingers II, III, IV with lateral fringes; bulla absent; (10) humeral spine absent; unknown for males, but presumably absent; (11) webbing present between all toes; (12) toe discs slightly spread out, bluntly truncated; pointed projection lacking on toe I disc; (13) dorsum shagreened, numerous small warts and fewer large warts; warts also present on ulnar and external tarsal areas; (14) melanophores numerous, present on outside of fingers and toes; (15) pericardium covered by guanophores; parietal peritoneum also covered by guanophores spreading out to the liver and half the stomach; all other visceral peritonea clear; (16) tri-lobed liver; (17) ventral skin granular; (18) anus ornamented by enameled warts; pair of subanal tubercles absent; (19) bones green in life, white in preservative. Head, dorsum, flanks, and limbs viridian green covered with numerous enameled, bright white spots on flat warts and sprinkled larger dark blue spots on warts. Upper lip white, iris light grey with fine darker gray reticulations. Points of finger and toe discs yellow. Melanophores on outer fingers and toes. White pericardium, white parietal peritoneum extending to liver and over posterior half of stomach, all other visceral peritonea clear. Bones green.The name is derived from the Latin word ermineus , meaning "white like ermine," in reference to the glossy, bright white warts that ornament the dorsum of Rulyrana erminea.

This species is known only from a single locality in Amazonian Peru, in the department of Junín, by the Sabetari stream. The area is a primary lowland forest with dense forest (canopy height taller than 30m) and semi-dense bamboo forest. The female holotype was found on a leaf of a tree that had fallen next to the slowly running stream.

The holotype was found at night, perched 30cm above the ground, on the leaf of a 20m tree that had fallen next to a seasonally slow flowing stream with a rocky bottom. Mating call and larvae as yet unknown. Syntopic with Eleutherodactylus cf. buccinator.

The Amazonian Junín area is relatively undisturbed by humans.