Usambara torrent frog

The Usambara torrent frog (Arthroleptides martiensseni), also known as Martienssen's torrent frog or Tanzania rocky river frog, is a species of frog in the family Petropedetidae. It is endemic to the Usambara Mountains of Tanzania, where it is found 200–1,000 m (656.2–3,280.8 ft) above sea level. It is one of many, often taxonomically unrelated, frogs referred to as torrent frogs. It is mostly grey brown to yellowish brown, with a lighter underside and a dark stripe extending from the nostril to the shoulder, and can grow 59 mm (2.3 in) long.

The species was first described in 1911 by German zoologist Fritz Nieden, who studied a series of specimens collected two years prior. The scientific name is derived from Arthroleptis, a genus of frogs which this species bears some resemblance to, and Georg Martienssen, the German military commander who collected a specimen of this species. Some populations once thought to belong to this species are now known to represent different, related species such as the southern torrent frog. This frog is largely associated with rocky streams in montane forests, but can also be found in forest leaf litter far from water. It is a nocturnal species, emerging from shelters beneath boulders at night to catch prey such as smaller frogs. Eggs are laid on rocks close to torrential streams and waterfalls. The tadpoles remain attached to the rocks, where they develop, not entering the water. The species has been listed as Endangered by the IUCN as it is threatened by habitat loss and possibly the fungal disease chytridiomycosis.