Iain Darbyshire

Documenting biogeographical patterns of African timber species using herbarium records: a conservation perspective based on native trees from Angola.

In many tropical regions the development of informed conservation strategies is hindered by a dearth of biodiversity information. Biological collections can help to overcome this problem, by providing baseline information to guide research and conservation efforts. This study focuses on the timber trees of Angola, combining herbarium (2670 records) and bibliographic data to identify the main timber species, document biogeographic patterns and identify conservation priorities. The study recognized 18 key species, most of which are threatened or near-threatened globally, or lack formal conservation assessments. Biogeographical analysis reveals three groups of species associated with the enclave of Cabinda and northwest Angola, which occur primarily in Guineo-Congolian rainforests, and evergreen forests and woodlands. The fourth group is widespread across the country, and is mostly associated with dry forests. There is little correspondence between the spatial pattern of species groups and the ecoregions adopted by WWF, suggesting that these may not provide an adequate basis for conservation planning for Angolan timber trees. Eight of the species evaluated should be given high conservation priority since they are of global conservation concern, they have very restricted distributions in Angola, their historical collection localities are largely outside protected areas and they may be under increasing logging pressure. High conservation priority was also attributed to another three species that have a large proportion of their global range concentrated in Angola and that occur in dry forests where deforestation rates are high. Our results suggest that timber tree species in Angola may be under increasing risk, thus calling for efforts to promote their conservation and sustainable exploitation. The study also highlights the importance of studying historic herbarium collections in poorly explored regions of the tropics, though new field surveys remain a priority to update historical information.

Important Plant Areas: revised selection criteria for a global approach to plant conservation

Despite the severe threats to plant habitats and high levels of extinction risk for plant species in many parts of the world, plant conservation priorities are often poorly represented in national and global frameworks because of a lack of data in an accessible and consistent format to inform conservation decision making. The Important Plant Areas (IPAs) criteria system offers a pragmatic yet scientifically rigorous means of delivering these datasets, enabling informed national- or regional-scale conservation prioritisation, and contributing significantly towards global prioritisation systems including the International Union for Conservation of Nature Key Biodiversity Areas (KBAs) Standard. In this paper, we review the IPA rationale and progress on IPA identification to date, including the perceived limitations of the process and how these may be overcome. We then present a revised set of criteria for use globally, developed through the combined experiences of IPA identification over the past decade and a half and through a recent global consultation process. An overview of how the revised IPA criteria can work alongside the newly published KBA Standard is also provided. IPA criteria are based around a sound, scientific, global framework which acknowledges the practical problems of gathering plant and habitat data in many regions of the world, and recognises the role of peer reviewed expert opinion in the selection process. National and sub-national engagement in IPA identification is essential, providing a primary route towards long term conservation of key sites for plant diversity. The IPA criteria can be applied to the conservation of all organism groups within the plant and fungal kingdoms.

Origin of African Physacanthus (Acanthaceae) via wide hybridization.

Gene flow between closely related species is a frequent phenomenon that is known to play important roles in organismal evolution. Less clear, however, is the importance of hybridization between distant relatives. We present molecular and morphological evidence that support origin of the plant genus Physacanthus via “wide hybridization” between members of two distantly related lineages in the large family Acanthaceae. These two lineages are well characterized by very different morphologies yet, remarkably, Physacanthus shares features of both. Chloroplast sequences from six loci indicate that all three species of Physacanthus contain haplotypes from both lineages, suggesting that heteroplasmy likely predated speciation in the genus. Although heteroplasmy is thought to be unstable and thus transient, multiple haplotypes have been maintained through time in Physacanthus. The most likely scenario to explain these data is that Physacanthus originated via an ancient hybridization event that involved phylogenetically distant parents. This wide hybridization has resulted in the establishment of an independently evolving clade of flowering plants.

Striga magnibracteata (Orobanchaceae) a new species from Guinée and Mali

SummaryStriga magnibracteata Eb. Fisch. & I. Darbysh. is newly described from the Guinean savannas of eastern Guinée and southwestern Mali. Its affinity to S. klingii (Engl.) Skan, S. dalzielii Hutch. and S. macrantha (Benth.) Benth. is discussed and its conservation status is assessed.

A reassessment of the status of Barleria sect. Cavirostrata (Acanthaceae) in tropical Africa, with a new species, B. richardsiae, described from the Tanzania-Zambia border region

SummaryThe delimitation of Barleria L. sect. Cavirostrata M. Balkwill is discussed with particular emphasis on capsule and seed characters. An expanded circumscription of the section is adopted in which all species having a (potentially) 4-seeded capsule with a conspicuous beak and with subellipsoid, subglobose or discoid seeds are included. Barleria descampsii Lindau, previously placed within sect. Stellatohirta M. Balkwill largely on account of its stellate indumentum, is transferred to sect. Cavirostrata together with the closely related B. grandipetala De Wild. and B. richardsiae I. Darbysh., the latter being formally described here. A key to the four eastern African species of the newly expanded sect. Cavirostrata is presented, together with taxonomic notes and conservation assessments for each species.

The genus Isoglossa (Acanthaceae) in west Africa

SummaryThe genus Isoglossa Oerst. (Acanthaceae) is revised in west Africa, with particular emphasis upon the Cameroon Highlands. Four species are recognised, including Isoglossa dispersa I. Darbysh. & L. J. Pearce newly described here, and a second new species for which further flowering material is required before description, here called Isoglossa sp. A. Lectotypes are chosen for I. glandulifera Lindau and I. nervosa C. B. Clarke and the status of the latter species in relation to the eastern African I. membranacea C. B. Clarke is discussed. The habitat, ecology and conservation status of each species are considered, and gregarious mass-flowering is reported in I. dispersa.

Taxonomic notes and novelties in the genus Isoglossa (Acanthaceae) from east Africa

SummaryA review of the genus Isoglossa Oerst. in east Africa is presented in preparation for the FTEA Acanthaceae treatment. Variation in pollen type within the African Isoglossa is summarised and its implications for generic circumscription are considered. The occurrence of periodic gregarious monocarpy (a plietesial life cycle) within Isoglossa is reviewed, with reference to other occurrences of this phenomenon in the Acanthaceae. The relationship of African taxa of Isoglossa to the Asian I. dichotoma (Hassk.) B. Hansen is reviewed and a tabular synopsis and key are presented for this group in east Africa, together with the description of three new species (I. paucinervis, I. ventricosa, I. bondwaensis), one new subspecies (I. membranacea subsp. septentrionalis) and one new name (I. bruceae) within the group. A further three new east African species (I. variegata, I. faulknerae, I. multinervis) and one new subspecies (I. substrobilina subsp. tenuispicata) are described, and the status of I. salviiflora in relation to I. floribunda is reassessed. The conservation status of each taxon is considered.

A new species and a revised record in Namibian Barleria (Acanthaceae)

SummaryBarleria grootbergensis I. Darbysh. & E. Tripp is described from the Grootberg Pass in Kunene Region, Namibia. Its affinities within Barleria sect. Somalia are discussed. A second taxon, named as Barleria galpinii C. B. Clarke in the Prodromus einer Flora von SüdwestAfrika, is reassessed and found to be referable to B. pseudosomalia I. Darbysh., a species previously known only from central Tanzania. A revised checklist to the Barleria of Namibia is presented.

New species and range extensions from Mt Namuli, Mt Mabu and Mt Chiperone in northern Mozambique

SummaryThe three sections of this paper report on i) new species, ii) new records for the Flora Zambesiaca region and for Mozambique and iii) expansion of distributions of species previously thought to be endemic to particular mountains. Specimens have been collected from three mountains in north-central Mozambique visited during a collecting programme from 2006 to 2008 investigating the conservation value of the biodiversity of currently unprotected areas. Three new species: Crotalaria namuliensis, Isoglossa namuliensis and Helixanthera schizocalyx are described. Five taxa not previously recorded from the Flora Zambesiaca region are here recorded as new records for the region and 31 taxa are listed from Mozambique for the first time, including five taxa previously thought to be Malawi mountain endemics. The number of range extensions recorded from these Mozambican mountains is evidence of the paucity of specimens collected from this part of Mozambique and shows the need for continued collection in order to clarify the distributions of this region’s rarest species.

New species in Barleria sect. Stellatohirta (Acanthaceae) from Africa

SummaryThree new species are described in Barleria L. sect. Stellatohirta M. Balkwill from tropical Africa: B. aristata from south-central Tanzania, B. aenea from south-western Tanzania and northeast Zambia, and B. purpureotincta from south-western Zambia. Their affinities and conservation status are discussed.