A new species of Arthroleptis (Anura: Ranidae) from the West Usambara Mountains, Tanzania Alice G. C. Grandison Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD The herpetology of the Usambara Mountains, Tanga Province, Tanzania is primarily based on the extensive collections made by Loveridge (Barbour & Loveridge, 1928). He concen-trated his efforts on the more accessible eastern half of the Usambaras, especially around Amani (506'S: 3837'E) at an elevation of around 923 m and appears to have been the only person who collected amphibians in the Mt. Lutindi outlier (Hindu of Moreau, 1935), the only part of East Usambaras that rises above 1219 m and has a patch of highland and cedar forest on its peak (1 506 m) similar to that which, until comparatively recently, covered a vast area of West Usambaras (Moreau, 1935). Both the East and West Usambaras consist of high mountains with dramatically steep cliffs and ridges but the western peaks and plateaux are all above 1219m, their highest ridges reach 2286 m and the rainfall is considerably less. The eastern and western divisions of the mountains are divided by the hot, dry trench-like Lwengera Valley which is nearly 914m deep. The forests of the Highland Zone of the West Usambaras, as defined by Moreau (1935) in his excellent account of the topography, ecology and climate of these ancient mountains, remained virtually untouched by herpetologists until the last decade when collecting has been carried out by the writer and other zoologists, notably at ca 1 530 m, 37-8 km NE Soni above Mombo at the Mazumbai Forest Reserve and tea plantation, 448'S: 3829'E. This Forest Reserve consists of over 600 acres given to the University of Dar es Salaam by the owner of the tea plantation, Mr John Tanner. The most profitable collecting by the writer was done at 1530 m where an irrigation channel about 1-25 m wide follows the contour from a waterfall and river in forest passing through the forest to emerge in part of the plantation. The stream of approximately 140 mm depth had a slack to moderate current with a fine gravel and mud base. On its right bank it was overhung by forest trees while its left bank had a muddy track of sodden leaves plus debris backed by balsam and wild banana. The forest trees included Ocotea usambarensis and Newtonia. Average annual rainfall measured over a seven year period (1954/60), was 1041 mm. From a stone and debris in the stream and from the stream margin five Arthroleptis were obtained. These together with specimens found later by other collectors, at Mazumbai and additional localities in the West Usambaras between 1450m and 2134m, surpass in adult size all known species of Arthroleptis. In colour pattern and some proportions they resemble A. affinis Ahl, and to a much lesser extent A. adolfifriederici Nieden. A comparison of them with long series of affinis obtained mainly at the type locality, Amani in the East Usambaras, and with the type and paratype of Ruandan adolfifriederici suggests that an undescribed species of Arthroleptis exists in the West Usambara Mts. The new species is named after Mr John Tanner in recognition of the generosity and hospitality afforded the collectors and other zoologists and his keen interest in the natural history of Mazumbai. Abbreviations BM(NH)British Museum (Natural History), London FMNH Field Museum of Natural History, Chicago R Universitetets Zoologiske Museum, Copenhagen ZMB Zoologisches Museum der Humboldt-Universitat Berlin Bull. Br. Mm. nat. Hist. (Zool.) 45 (2): 77-84 Issued 28 July 1 983 77
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