Psychrophrynella wettsteini Psychrophrynella wettsteini Psychrophrynella wettsteini is a species of frog in the family Craugastoridae. It is endemic to Bolivia and only known from the region of Unduavi in the Unduavi Valley, Sud Yungas Province, La Paz Department. Common name Wettstein's Andes frog has been coined for it. It is named for Otto von Wettstein, Austrian zoologist. "Psychrophrynella wettsteini" is a comparatively large species (maximum snout–vent length ) and has a robust body and long limbs. The snout is rounded. The tympanic membrane is absent, whereas the tympanic annulus is visible through the skin. Tips of the digits are only slightly swollen.
Basilar membrane membrane is also the "base" for the sensory cells of hearing, the hair cells that are equipped with "Stereocilia". There are approximately 15,000 hair cells in each human ear (see figure). This function as base of the sensory cells gave the "basilar" membrane its name, and it is again present in all land vertebrates. Due to its location, the basilar membrane places the hair cells in a position where they are adjacent to both the endolymph and the perilymph, which is a precondition of hair cell function. A third, evolutionarily younger, function of the basilar membrane is strongly developed in