Du Toit's torrent frog

Du Toit's torrent frog, the Mt. Elgon torrent frog, or the Kenya rocky river frog (Arthroleptides dutoiti) is a possibly extinct species of frog in the family Petropedetidae. It is endemic to Mount Elgon, where it has been observed along fast-flowing montane streams surrounded by dense forest in Kenya; it has not been found on the Ugandan part of the mountain, but is expected to occur in more localities than those it has been found in. This species rests on rocks and logs near these streams, sometimes hanging to them like an insect, or in the water beneath them, and is a capable swimmer. It is one of numerous species of frog commonly described by the polyphyletic designator "torrent frog."

This frog is small, with the holotype individual growing 31 mm (1.2 in) in snout–vent length, and has warty and pitted skin on its back but smooth skin elsewhere. The digits are widened into disks at the tips, with webbing between the toes but not the fingers that extends halfway down the toes. The coloration of live individuals is reportedly dark gray or black with speckles on the upper surface, and lighter gray with spots on the underside, with vertical bands on the legs, a golden line over the iris, triangular patterns on the snout, white edges on the digit tips and a line of pale dots over the anus. The males are known to make calls from sheltered areas during the rainy season and occupy territories of at least 5 sq in (32.3 cm²). The large, pigmented eggs each measure around 3 mm (0.1 in) and are presumably laid on wet rocks where the tadpoles develop, rather than directly in the water.

The species is named after Cornelius Albertus du Toit, who discovered the species in 1934 while conducting a reptile and amphibian survey along the Koitobos River, during which he collected the holotype specimen and two other individuals. The only other known sighting of this species was in 1962, when Ronalda Keith found a population at the Suam River. Despite repeated surveys conducted on Mount Elgon from 2001 onwards, the Du Toit's torrent frog has not been recorded since Keith's sighting and has been feared extinct, though evidence remains insufficient to officially declare it as such. While the exact causes of its decline remain uncertain, habitat loss and the fungal disease chytridiomycosis have been proposed as threats to the species.