Olea chimanimani, MOUNTAINS

THE CHIMANIMANI MOUNTAINS View in CoL

The Chimanimani Mountains View in CoL , which are situated towards the north-eastern limit of the Great Escarpment of southern Africa ( Clark et al. 2011), have long been known for their botanical importance, in particular for their high number of endemic species (see, for example, Goodier & Phipps 1961, Wild 1964). Van Wyk & Smith (2001) designated this area as the Chimanimani subcentre of endemism within the wider Chimanimani-Nyanga Centre. Until very recently, however, only the Zimbabwean side of the massif was well known botanically, and the much larger Mozambican portion of the massif remained under-explored. Following a series of botanical surveys on the Mozambican Chimanimani in 2014–2016 supported by a ‘Critical Ecosystem Partnership Fund (CEPF)’ grant ( Timberlake et al. 2016), a comprehensive checklist of species occurring above 1 200 m on the massif is now available. A total of 977 taxa is recorded including 74 strict endemic and 19 near-endemic taxa ( Wursten et al. 2017). For these reasons alone, Chimanimani will merit rating as two Tropical Important Plant Areas (TIPAs), one on each side of the border, using the criteria of Darbyshire et al. (2017). The endemism rate on Chimanimani (7.7 %) is mark- edly higher than that of other comparable mountain ranges of southern tropical Africa – for example, the Nyanga massif in Zimbabwe (1.4 %) and Mt Mulanje in Malawi (5.4 %) ( Strugnell 2002, Clark et al. 2017, Wursten et al. 2017). This high endemism is concentrated on the extensive outcrops of quartzite which result in thin, nutrient-poor and phosphorus-deficient soils that encourage local speciation through specialisation to these harsh growing conditions ( Phipps & Goodier 1962, Wild 1964, Wursten et al. 2017). Indeed, many of the endemics are from plant groups typical of nutrient-poor soils, including four species of Thesium View in CoL , one endemic and two near-endemic Erica species, and one of the few tropical African restio species, Platycaulos quartziticola (H.P.Linder) H.P.Linder & C.R.Hardy. Others View in CoL are typical of rocky environments including four endemic species of Aloe and several species in the African Asclepias View in CoL complex ( Chuba et al. 2017, Goyder 1998, 2001, 2009), or of associated seasonal wet flushes over thin soils, such as Xyris asterotricha Lock View in CoL , Mesanthemum africanum Hassk. View in CoL and Centella obtriangularis Cannon. Whilst View in CoL most of the endemic species are herbs or ericaceous shrubs, the new Empogona View in CoL described here is one of a small number of woody endemics which include Olea chimanimani Kupicha View in CoL , Sericanthe sp. B of Flora Zambesiaca and a new species of Olinia View in CoL currently under description (T. Shah & I. Darbyshire, in prep.). A number of other potentially new endemic species were discovered during the 2014–2016 surveys, including a species of Streptocarpus View in CoL and a species of Indigofera ( Wursten et al. 2017) View in CoL .

Following a long period of relative neglect in terms of biodiversity research, driven in part by the protracted period of unrest associated with the war of independence (1964–1975) and subsequent civil war (1977–1992), Mozambique has seen a recent upsurge in botanical exploration over the past decade and a half. Although the total flora is currently unknown due to under-exploration of many areas, the species richness is likely to be the highest of the Flora Zambesiaca region. New surveys at botanically interesting sites in Mozambique are routinely producing new country records and new species. For example, botanical expeditions to Mt Namuli in Zambezia Province in 2007 resulted in the discovery of four entirely new species to science – Coleus namuliensis E.Downes & I.Darbysh. View in CoL , Crotalaria namuliensis Polhill & T.Harris View in CoL , Isoglossa namuliensis I.Darbysh. View in CoL and Crepidorhopalon View in CoL sp. nov. ined. – as well as 28 new taxon records for Mozambique ( Harris et al. 2011, Downes & Darbyshire 2017). Of even greater note, during surveys of the coastal dry forests of northeastern-most Mozambique in Cabo Delgado Province between 2003 and 2009, of the 738 plant taxa recorded from over 3 000 botanical collections, 68 new species records for Mozambique were listed and an additional 36 taxa were either entirely new to science or previously known only from fragmentary material and so undescribed ( Timberlake et al. 2011). Several of these species have subsequently been described, including Didymosalpinx callianthus J.E.Burrows & S.M.Burrows View in CoL and Oxyanthus biflorus J.E.Burrows & S.M.Burrows View in CoL in Rubiaceae ( Burrows & Burrows 2010) View in CoL , Stylochaeton tortispathum Bogner & Haigh View in CoL in Araceae View in CoL (in Haigh & Boyce 2012), Warneckea cordiformis R.D.Stone ( Stone 2013) View in CoL , Ochna dolicharthros F.M.Crawford & I.Darbysh. View in CoL in Ochnaceae ( Crawford & Darbyshire 2015) View in CoL , Xylopia lukei D.M.Johnson & Goyder View in CoL and X. tenuipetala D.M.Johnson & Goyder View in CoL in Annonaceae ( Johnson et al. 2017) View in CoL and Crossopetalum mossambicense I.Darbysh. View in CoL in Celastraceae ( Darbyshire et al. 2016) View in CoL . The lattermost discovery led to the recognition of the genus Crossopetalum P.Browne View in CoL in Africa for the first time, it previously having been considered a New World genus ( Darbyshire et al. 2016).

The continued botanical exploration of Mozambique over forth- coming years will no doubt lead to many more species discoveries and will provide us with a much clearer understanding of the total species richness of this fascinating and diverse country.

Acknowledgement Janis Shillito is thanked for typing the manuscript and David Goyder for reviewing an earlier version of the manuscript.