Psychrophrynella wettsteini species without known major threats. 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
Cell membrane cells to hold them together to form tissues. Fungi, bacteria, most archaea, and plants also have a cell wall, which provides a mechanical support to the cell and precludes the passage of larger molecules. The cell membrane is selectively permeable and able to regulate what enters and exits the cell, thus facilitating the transport of materials needed for survival. The movement of substances across the membrane can be either "passive", occurring without the input of cellular energy, or "active", requiring the cell to expend energy in transporting it. The membrane also maintains the cell potential. The cell membrane thus works