British Bryological Society Expedition to Mulanje Mountain, Malawi. 12. A revision of the genus Rhacopilopsis Renauld & Cardot (Hypnaceae, Bryopsida)

Abstract

Based on studies of 487 specimens, the pleurocarpous moss genus Rhacopilopsis is reviewed world-wide, and two taxa are recognised: R. trinitensis (Müll.Hal.) E.Britt. & Dixon (new synonyms: Acanthocladiella kilimandscharica Broth. & P.de la Varde, A. transvaaliensis Thér. & Dixon ex Sim, Dimorphella brasiliensis Broth. & Herzog, D. pechuelii var. acuminata Cardot, D. pechuelii var. gracilis Cardot and Rhacopilopsis trinitensis vars. pendula P.de la Varde and perserrata J.Taylor & P.de la Varde and fo. densa Tosco & Piovano) and R. variegatum (Welw. & Duby) M.C.Watling & O'Shea, comb. nov. (basionym: Hypnum variegatum Welw. & Duby; new synonyms: Microthamnium flexile Renauld & Cardot, Pylaisaea guineensis Broth. & Paris and Stereodon albo-alare Broth.). Both taxa are fully illustrated and a key is presented. Rhacopilopsis trinitensis is characterised by complanate shoots and up to four rows of supra-alar cells and is known from Central America and the northern part of South America, tropical Africa, South Africa and Madagascar. Rhacopilopsis variegatum differs from R. trinitensis in having non-complanate shoots and four or more rows of supra-alar cells and is endemic to Africa, occurring over a similar range to R. trintenisis, but less frequently and usually at greater elevations.