Endémisme et valeur de conservation des cuprophytes du Katanga (en prép.)Katanga (en prép.)

Michel-Pierre Faucon, Arthur Meersseman, Mylor Ngoy Shutcha, Grégory Mahy, Michel Ngongo Luhembwe, F. Malaisse, P. Meerts

Résumé :

Au Katanga, les affleurements naturels de roches riches en cuivre sont colonisés par des communautés végétales très originales. Certaines espèces ont été proposées comme des endémiques probables de ces sites. Dans cette présente étude, nous avons révisé le statut taxonomique, phytogéographique et conservatoire de ces plantes. Trente trois taxons sont identifiés comme des endémiques strictes des sols cuprifères du Katanga (endémiques strictes). Dix-huit autres taxons sont identifiés comme endémiques larges, c’est-à-dire avec une fréquence supérieure ou égale à 75% sur sols riches en cuivre. La faible proportion d’endémiques (environ 5%) dans la flore des sols cuprifères indique éventuellement d’une origine récente de celle-ci (c’est-à-dire holocène). Les arguments en faveur d’un néoendémisme sont discutés. La plupart des endémiques strictes sont en danger critique d’extinction à cause de la destruction de leurs habitats par l’exploitation du cuivre. Par contre, certaines espèces sont capables de coloniser les habitats métallifères secondaires crées par l’industrie minière et sembleraient moins menacées.

Mots clefs: métallophyte, endémisme, cuivre, Katanga, mining, métaux lourds

Copper endemism in the Congolese flora: A database of copper affînity and conservation value of cuprophytes

M.-P. Faucon* • A. Meersseman* • M. Ngoy Shutcha • G. Mahy • M. Ngongo Luhembwe ® F. Malaisse • P. Meerts

* equally contributing first authors

Michel-Pierre Faucon, Arthur Meersseman and Pierre Meerts. Laboratoire de Génétique et Ecologie végétales - Université Libre de Bruxelles. 1850, chaussée de Wavre, B-1160 Bruxelles, Belgium

Grégory Mahy and François Malaisse. Laboratory of Ecology. Gembloux Agricultural University. Passage des Déportés 2, 5030 Gembloux, Belgium

Michel Ngongo Luhembwe and Mylor Shutcha. Université de Lubumbashi. Faculté des Sciences Agronomiques Lubumbashi, Rep. Dem. of Congo.

Abstract : In Katanga, natural outcrops of copper-rich rocks are colonised by highly original plant communities. A number of plant species hâve been proposed as possibly endemic of these sites. We here revise the taxonomie, phytogeographic and conservation status of these plants. 33 taxa are identified as strictly endemic of Cu-rich soil in Katanga (strict endemics). 18 other taxa are identified as broadly endemic, i.e. with >75% of occurrence on Cu-rich soil. Low proportion of endemics (ca. 5%) in the flora of Cu-rich soil possibly indicates a recent origin (i.e. Holocene) of much of this flora. Arguments in favour of neoendemism are discussed. Most strict endemics are critically endangered, due to habitat destruction by copper mining. Several species, however, are able to colonise secondary metalliferous habitats created by mining industry and may be at lower risk.

Key Words: metallophyte, endemism, copper, Katanga, mining, heavy metals

Introduction

Plant communities developed on geochemical anomalies often comprise a high proportion of endemic plant species and ofFer outstanding examples of ongoing microevolutionary processes (Antonovics et al. 1971; Ernst 1974; Baker et al. 1992). Metalliferous substrates are remarkable geochemical anomalies often having a highly distinctive flora and végétation and are therefore of high value to biodiversity conservation (Whiting et al. 2004). Outcrops of metalliferous rocks support high and unique plant diversity throughout the world (Whiting et al. 2004). Geographical isolation, ecological isolation and stringent sélective forces hâve been invoked to explain evolutionary divergence and endemism in geochemical anomalies (Raven

1964; Kruckeberg 1984, 1986; Rakajaruna 2004).

Metallophytes are species that possess physiological adaptations required to grow on substrate enriched in heavy metals (Baker & Walker 1990; Baker et al. 2000). Metallophytes are interesting species both from a fimdamental viewpoint (evolutionary biology, physiology) and in a more applied perspective. They can be used to implement green technologies aimed at remediating heavy métal pollutions.

Serpentine soils are by far the metalliferous substrate that occupies the largest areas on the earth. Therefore, they hâve received much attention from an ecological and evolutionary point of view (Wild 1965, 1974; Duvigneaud 1966; Kruckeberg 1984; Jaffré 1992; Borhidi 1996; Rajakaruna & Bohm 2002; Reeves et al. 2007). In contrast, other natural metalliferous substrates occupy much smaller areas and hâve been comparatively less well studied. Ecosystems established on soils naturally contaminated with Cu are of rare occurrence on the earth. SC Africa is exceptional by the occurrence of a large number of copper-cobalt mineralised areas, with an unique végétation (Duvigneaud & Denaeyer-De Smet 1963, Ernst

1974, Wild & Bradshaw 1977, Brooks & Malaisse 1985).

In South Central Africa, in particular the Katangan copper belt (Démocratie Republic of Congo), Cu-rich rock outcrops are remarkable in the landscape in the form of hillocks covered by steppic savannah surrounded by the miombo woodland (Brooks & Malaisse 1985; Leteinturier 2002). Toxicity of copper, most often associated to cobalt and other heavy metals créâtes an ecological isolation of this habitat. Moreover, as outcrops are not contiguous.

copper hills are also geographically isolated across the Katangan copper belt. The history of botanical exploration of Cu-Co soils in SC Africa was reviewed by Leteinturier & Malaisse (2001). For a long time, botanists hâve relied on the séminal work of Duvigneaud for most of their information on Katangan metallophytic plant taxa (Duvigneaud 1958; Duvigneaud 1958; Duvigneaud 1959; Duvigneaud & Denaeyer-De Smet 1963). More recent explorations hâve added a substantial number of taxa to the flora of Cu-soil, including a few new endemic species (Robyns 1989; Malaisse & Lecron 1990). However, progress in the botanical exploration of Katanga has also revealed that taxa previously regarded as endemic also occurred, at varions frequencies, on normal soil. At the sarae time, taxonomie révisions hâve synonymised a number of taxa regarded by Duvigneaud as Cu-endemics. The régional copper flora comprises some 600 taxa présent on approximately 160 metalliferous sites (Leteinturier 2002; Malaisse pers. com.). Some forty species are regarded as endemic of the copper habitat (Leteinturier 2002; Whiting et al. 2004). Katanga copper belt constitute a hotspot for metallophyte species (Wild & Bradshaw 1977; Brooks & Malaisse 1985, 1990; Malaisse

1983; Malaisse et al. 1983).

AU over the world metalliferous soils are hotspots of biodiversity that are threatened by human activities, noticeably mining, and Katanga makes no exception. Actions aiming to préservé metallophyte species are impérative (Whiting et al. 2004). Indeed, intensive mining exploitation threatens the habitat of rare copper tolérant species. A dozen of sites are already completely destroyed and many others hâve been disturbed (Brooks et al. 1992). Several endemic taxa may hâve already gone extinct (Brooks et al. 1992). Katangan copper species hâve not been included in the lUCN Red List and this may seriously undermine conservation efforts (for a discussion of appropriate uses of the Red List, see Possingham et al. 2002; Lamoreaux et al. 2003).

A full appréciation of biogeographic originality and conservation value of a given area must rely on a suffïcient taxonomie knowledge. Africa has recently been referred to as the “dark” continent for botanical taxonomy and phytogeography (Pimm 2007). The gap between taxonomy and conservation science represent a biggest challenge today because there are still many unnamed and imperfectly known species in the world requiring conservation effort (Golding & Timberlake 2003). Understanding plant taxonomy and diversity is an indispensable for conservation status. Arguably, taxonomie research priorities could concentrate on threatened (or potentially threatened) using preliminary lUCN Red List

assessments (Callmander et al. 2005). For the Congolese flora, less than one-third of the flora has been revised (Flore d’Afrique Centrale (Jardin Botanique National de Belgique 1972)).

In this paper, we aim to establish a check-list of species endemic of Cu-rich soil in Katanga (Démocratie Republic of Congo), and to assess their current distribution range and conservation. To that end, we revise taxonomie status and ecogeographical distribution of virtually ail taxa that hâve ever been reported to be endemic of Cu-rich soil in Katanga, based on an extensive révision of herbarium materials. We also provide a first assessment of their conservation status using the lUCN typology.

Geographical setting and climate

The “Katangan Copper Belt” (Démocratie Republic of Congo) forms a crescent ca 300 km long and 50 km wide extending from Kolwezi in the west to Lubumbashi in the southeast of Katanga province. Mineralised rocks appear as rounded hills, typically a few tenths of meters above the level of the surrounding non mineralised areas. Most copper hills are typically less than 1 km^. The distance between nearby hills varies enormously across the copper belt ffom less than a few hundred meters to more than 20 km. Less than 100 hills hâve been visited at least on one occasion by a botanists (Leteinturier et al. 1999; Leteinturier 2002).

The Katangan Group is of Upper Cambrian âge (i.e. over 620 m.y. old). It comprises three large sériés: Upper Kundelungu, Lower Kundelungu and Roan (François 1973). Copper mineralization in Katanga province is found in the Roan Sériés. They are mainly calcareous rocks with dark minerais, dolomitic schists, cellular siliceous rocks, flaky siliceous rocks, stratified dolomites and argillaceous talc.

Climate is humid subtropical (KÔppen-Geiger: CWa) and tempered by the high élévation (ait. around 1300 m). There is one rainy season (November to the end of March), one dry season (May to September) and two transition months (October and April). Annual rainfall is about 1300 mm of which 1200 mm fall during the rainy season. At the beginning of the dry season, the herbaceous végétation scorches, except in the permanent wetlands. Mean annual température is about 20 °C. Température is lowest at the beginning of the dry season (15-17 °C). September and October are usually the warmest months with daily maxima of

about 31-33 °C. Température amplitude between day and night is low during the rainy season, but is larger during the dry season when night température can fall to 5 °C.

Material and methods

Three sources of information were used to construct a database: published literature, herbaria and unpublished observations by the authors (often with a herbarium voucher specimen).

First, a list of species was compiled based on ail published papers on the flora of Katangan copper hills with explicit indications indicating affinity with copper soil in Katanga (Robyns 1932; Duvigneaud 1958; Duvigneaud 1959; Duvigneaud & Denaeyer-De Smet 1963; Malaisse 1983; Brooks & Malaisse 1990; Leteinturier & Malaisse 1999; Leteintiuier 2002). Ail species that hâve once been regarded as endemics or as having high afïinity for Cu- rich substrate were included. Conceming publications by Duvigneaud, we retained species regarded by him as “absolute cuprophytes”, local cuprophytes and “cuprophiles”.

The second step was to validate putative endemics. Each species in the fîrst list was critically examined both ffom a taxonomie and phytogeographic point of view.

Nomenclatural and taxonomie révision

Ail relevant taxonomie révisions published either in standard floras or as monographs, hâve been examined. In ail cases, the protologue was consulted. The following standard floras hâve been used; Flore d’Afrique centrale (Jardin Botanique National de Belgique 1972), Flora Zambesiaca (Board of Trustées of the Kew Royal Botanic Gardens 2004) and Flora of Tropical East Africa (Kew Royal Botanic Gardens 1952-2008). The following electronic resources were aiso used; Botany & Plant Science of ALUKA (http;//www.aluka.org/action/showDiscipline?sa=bot). The International Plant Names Index ('http;//www.ipni.orgI. Base de dormées des plantes à fleurs d'Afrique (http;//wvm. ville- ge.ch/musinfo/bd/cib/africa/recherche.phpy The most recently accepted name has been retained. Nomenclature has been adapted accordingly. Some putative endemics were rejected because they hâve been synonymized with taxa with a broader distribution range ofF copper

substrates. In a limited number of cases, different taxonomie révisions bave expressed conflicting views as to the taxonomie value of taxa occurring on copper soil. Such cases will be examined in the discussion.

Phytogeographic révision

After nomenclatural and taxonomie validation, for ail species in the first list the proportion of locations on and off copper soils was determined based on an extensive survey of published literature and herbarium collections. For ail these species, virtually ail herbarium materials kept in BR, BRLU, BR VU, Kipopo herbarium (in Katanga) and GENT hâve been examined for location and ecology. Additional data came from our own observations (pers. obs.) and from the original fîeld notes of P. Duvigneaud. Particular attention was paid to records of putative endemics off copper substrates (nonmetalliferous habitats from Katanga; steppic savanna (dilungu) of Katangan highlands (Hauts-Plateaux katangais), nonmetalliferous rocks, lateritic crust, woodland miombo or other metalliferous habitats: Zn, Pb, Mn). More then 1900 herbarium sheets hâve been revised. Occurrence on copper was admitted if it was explicitly mentioned on the label. In a few cases, occurrence on copper soil is inferred from locality name (e.g. “Mine de l’Etoile”) even if no explicit ecological data are reported by the collector. However, possible ambiguities will be discussed.

AU localities recorded (including published literature, pers. Obs. and herbaria) were entered in the database.

Afïinity for copper was calculated as the proportion of records on copper soil and classifîed: <75 %, 75-99 %, 100%. Taxa with 100% of records on copper soil are here regardeef as strict ’endemics'of Katangan copper soil. Our définition of endemism is more restrictive than that recently used for Califomian serpentine as SafFord (2005), who regarded as serpentine endemics ail species with > 95% locations on serpentine. This is because of the much poorer botanical exploration of Katanga compared to California, which implies that a single authentic record off copper is sufficient to indicate a broader ecological range. A second list, with species having > 75% of localities on Cu-soil, and a few species with a total of 3 known localities, two of which (66%) on Cu soil.

Table 1 Plant taxa strictly endemic of Cu-rich soil in Katanga (Démocratie republic of Congo), with their lUCN status and ecology. Ex: extinct, CR: critically endangered, EN: endangered, VU: vulnérable, DD: data déficient, NE: not evaluated. Primary habitats = S: steppe; RS: rocky steppe; SS: steppic savanna; Sw: sward. Secondary habitats = (SI) with substrate (often mine débris) disturbed and reworked by mining activities

Taxon (accepted name) _{Synonyms Family sites lUCN status Habitats}

Acalypha cupricola A. Robyns _{EUPHORBIACEAE 51 (EN A2a + 3d) SS}

Acalypha dikuluwemis P.A. Duvign. & Dewit. _{EUPHORBIACEAE} 1 EX SS

Actiniopteris komasii Medweeka-Komas ’ _{PTERIDACEAE 4 (CR Bla+(b(i,ii,iii,iv))) RS}

AeoUemthus saxatilis P. A. Duvign. & Denaeyer _LAMIACEAE 4 (CR Bla+(b(i,ii,iii,iv))) RS

Aspilia eylesii S. Moore ssp. cupricola P. A. Duvign. & Danhier _{ASTERACEAE 1 DD S}

Basananthe cupricola A. Robyns _{PASSIFLORACEAE 1 (CR B2a+(b(i,ii,iii,iv))) SS}

Bulbostylis fusiformis Goetgh. _{CYPERACEAE 3 (CR B1 a+(b(i,ii,iii,iv)+(c(iii))) RS; Sw; SI}

Cheilanthes inaequalis KZE var. lanopetiolata P. A. Duvign. PTERIDACEAE 1 (CR B2a+(b(i,ii,iii,iv))) RS; Sw

Commelina mwatayamvoana P. A. Duvign. et Dewit COMMELINACEAE 2 (CRB2a+(b(i,ii,iii,iv))) S

Commelim zigzag P. A. Duvign & Dewit _{COMMELINACEAE} 5 (CR Bla+(b(i,ii,iii,iv))) Sw

Crepidorhopalon perennis (P.A Duvign.) Eb. Fisch. Lindemia perennis P. A. Duvign. SCROPHULARIACEAE 2 (CR B2a+(b(i,ii,iii,iv)+(c(iii))) SI

Crotalaria cobalticola P. A.Duvign. & Plancke FABACEAE 18 (EN B2a+(b(i,ii,iii,iv))) SS; SI

Crotalaria peschiana P. A. Duvign. & Timp. FABACEAE 5 (CR Bla+(b(i,ii,iii,iv))) SS

Cyanotis cupricola P. A. Duvign. COMMELINACEAE 13 (EN Bla+(b(i,ii,iii,iv))) RS

Cyperus kibweanus P. A. Duvign. CYPERACEAE 5 (CR Bla+(b(i,ii,iii,iv))) SS

Digitaria nitens Rendle ssp.festucoides P.A. Duvign. POACEAE 1 DD SR

Euphorbia cupricola (Malaisse & Lecron) Bruyns Monadenium cupricolaMalaisse & Lecron EUPHORBIACE AE _{5 (CR Bla+(b(i,ii,iii,iv))) RS}

Faroa chalcophila P. Taylor GENTIANACEAE 3 (CR Bla+(b(iii,iv)+c(iii))) SI

Faroa malaissei Bamps GENTIANACEAE 11 (CR Bla+(b(i,ii,iii,iv))) RS

Gutenbergia pubescens (S. Moore) C. Jeffrey Gutenbergia cuprophilaP,A. Duvign. ASTERACEAE 2 (CR B2a+(b(i,ii,iii,iv)+(c(iii))) SI

Hartliella cupricola Fischer SCROPHULARIACEAE 1 (CR B2a+(b(i,ii,iii,iv))) SS

Haumaniastrum robertii (Robyns) P. A. Duvign. & Plancke Acrocephalus robertii Robyns LAMIACEAE 32 (VU Bla+(c(iii))) SI

Ecology of endemics

Habitat of each species was determined based on herbarium collections, published literature and our own field observations. Three types of habitats hâve been distinguished. Primary habitats are natural, undisturbed plant communities. These are most often steppic savannah dominated mostly by perennial species. Secondary habitats are those established on substrates which hâve been disturbed by man. Two types of secondary habitats hâve been distinguished depending on the source of metallic contamination; i) rock débris disturbed by mining activities (whether artisanal or industrial) ii) soil contaminated by atmospheric fallout from copper smelters. Secondary metalliferous habitats are typically colonised by open plant communities often dominated by aimual species.

lUCN red list status

Using the ecogeographical information collected during the phytogeographical révision, the operating plan of mining and the observations of anthropogenic impact in Cu endemic sites, the lUCN Red List status (lUCN 2001) of each taxon was assessed. In this assessment, impacts of disturbance by mining activities hâve been considered as follows.

Results

The check-list

Our checklist of taxa with high affînity for Cu/Co substrates in Katanga currently comprises 49 taxa. 32 of these (28 species, 2 subspecies, 2 varieties) are strict Katangan Cu-endemics, i.e. with 100% of records on Cu-rich soil in Katanga (Table 1). Ten of these (30%) are known only from the type locality. Only seven are known from >10 localities.

Table 1 {Contd.)

4

Taxon (accepted name) _{Synonyms Family sites lUCN status Habitats}

Silene cobalticola P. A. Duvign. & Plancke _{CARYOPHYLLACEAE 1 (CR B2a+(b(i,ii,iii,iv))) SS}

Sopubia mannü Skan var. metallorum (P.A. Duvign.) Mielcarek Sopubia metallorum P.A. Duvign. SCROPHULARIACEAE 9 (CR Bla+(b(i,ii,iii,iv))) SS

Vemonia duvigneaudii Kalanda _{ASTERACEAE 2 (CR B2a+(b(i,ii,iii,iv))) RS}

Vemonia ledocteana P. A. Duvign. & Van BockstaJ ASTERACEAE 1 1 EX S

t

Vigna dolomitica Wilczek _{FABACEAE 1 (CR B2a+(b(i,ii,iii,iv)+(c(iii))) SI}

Wahlenbergia ericoidella (P.A. Duvign. & Denaeyer) Thuiin CAMPANULACEAE 3 (CR Bla+(b(i,ii,iii,iv))) s

Wahlenbergia malaissei Thuiin _{CAMPAMJLACEAE 2 (CRB2a+(b(i,ii,iii,iv)))} s

Table 2 Plant taxa with very high affinity to Cu/Co rich substrates in Katanga (Démocratie Republic of Congo) (75-99% of localities on Cu-soil in Katanga or a single locality off Cu-soil), with their lUCN status and ecology. Ex; extinct, CR; critically endangered, NT; near threatened, LC; least concem, DD; data déficient, NE; not evaluated. Primary habitats; S; steppe; RS; rocky steppe; SS; steppic savanna; Sw; sward. Secondary habitats = S31;with substrate (often mine débris) disturbed and reworked by mining activities, S2; soil contaminated by atmospheric fallout fi'om an ore-smelter

Accepted names Synonyms Family sites lUCN status Habitats

Anisopappus davyi S. Moore _ASTERACEAE 17 (VU Bla+(b(i,ii,iii,iv))) RSw; SI

Ascolepis metallorum P. A. Duvign, & Léonard CYPERACEAE 29 (VUBla+(c(iii))) S; SI

Basananthe kisimbae Malaisse & Bamps PASSIFLORACEAE 16 (EN B2a+(b(i,ii,iii,iv))) SS

Buchnera symoensiana Mielcarek Buchnera candida P, A. Duvign. & Van Bockstal SCROPHULARIACEAE 3 (EN Bla+(b(i,ii,iii,iv))) RS

Bulbostylis cupricola Goetghebeur CYPERACEAE 36 (VU Bla-Kc(iii))) SI

Bulbostylispseudoperemis Goetghebeur CYPERACEAE 24 (VU Bla+(c(iii))) S1;S2

Diplolophium marthozianum P. A. Duvign. Spuriodaucus marthozianus APIACEAE 10 (VU Bla+(b(i,ii,iii,iv))) SS

Dissotis derriksiana P. A Duvign, _{MELASTOMATACEAE} 13 (VU Bla+(c(iii))) RS;S2

Euphorbiafanshawei L.C. Leach EUPHORBIACEAE 3 (EN B2a+(b(i,ii,iii,iv))) RS

Gladiolus ledoctei P. A. Duvign. & Van Bockstal G.JùngurumeensisP.A. Duvign. & Van Bockstal IRIDACEAE 16 (VU Bla+(b(i,ii,iii,iv))) RS

Gladiolus robiliartianus P. A. Duvign. Gladiolus duvigneaudii Van Bockst. nUDACEAE 8 (EN Bla+(b(i,ii,iii,iv))) RS

Helichrysum lejolyamm Lisowski ASTERACEAE 7 (VU Bla+(b(i,ii,iii,iv))) SS

Ipomoea linosepala Hallier f. ssp. auroargentea P. A. Duvign. et Dewit

CONVOLVULACEAE 6 (VU Bla+(b(i,ii,iii,iv))) RS

Justicia metallorum P. A. Duvign. ACANTHACEAE 26 (VU Bla+(b(i,ii,iii,iv))) SS

Ocimum ericoides (P. A. Duvign. & Plancke) Paton Becium ericoides P.A. Duvign. & Plancke LAMIACEAE 5 (VU Bla+(b(i,ii,iii,iv))) SS

Sopubia neptunii P. A. Duvign, & Van Bockstal SCROPHULARIACEAE 17 (VU Bla+(b(i,ii,iii,iv))) Sw

Tinnea coerulea Gürke var. obovata (Robyns & Lebrun) Vollesen

Tinnea obovata Robyns & Lebrun LAMIACEAE 10 (VUBla+(b(i,ii,iii,iv))) SS

18 taxa (16 species, 1 subspecies, 1 variety) hâve >75% of their localities on Cu-soil in Katanga can be referred to as “broad endemics” (Table 2). Ascolepis metallorum is an absolute metallophyte not confined to Cu-soil, extending to a broader range of metalliferous substrates including Zn/Pb and Mn-rich soil. Bulbostylis cupricola is restricted to Cu-soil, but its distribution range extends to the copperbelt of Zambia. The 15 other taxa hâve a few occurrences (sometimes a single) on non-metalliferous soil. In many cases, these “odd” localities are not located close to Cu-sites, most often occurring in the steppic végétations of Katangan Highlands on Kalahari sands (“Hauts Plateaux katangais”). Most of these “broad endemics” are known ffom 10 localities or more.

65 other taxa which had been previously reported by at least one reference to be endemic of Cu substrates hâve been rejected for one or several of the following reasons (Table 3). First, a number of putative endemics hâve been shown to be of little taxonomie value and were merged with taxa with a broader distribution range (e.g. Xerophyta barbarae

synonymised with the widespread X. equisetoides). A second group comprises valid taxa which hâve been discovered in a relatively large number of sites on non mineralized soil (e.g.

Gladiolus tshombeanus). Finally, a number of supposed endemics tumed out to hâve never been validly published yet and were therefore rejected as nomina nuda. It must be emphasized that some of the “rejected endemics” are characteristic components of Cu-vegetations

{Uapaca robynsii, Gladiolus tshombeanus, Aeollanthus subacaulis, ... ). A distinct group comprises species with <75% of their localities on Cu-soil when considering their whole distribution range, but which occur (almost) exclusively on Cu-soil in the Katangan copperbelt. These can be referred to as “régional Cu-indicators”. The most characteristic of them are listed in Table 4.

Table 3 Plant taxa formerly reported as endemics of Cu-soil and which are not validated in the présent study. K = Katanga; BC = Bas Congo; ZA Zambia; AO = Angola; TZ = Tanzania; RW = Rwanda; MI = Malawi; ZI = Zimbabwe; MZ = Mozambic

4

Name _{currently accepted name Family Distribution}

range

Révision

Acrocephalus katangensis S.Moore Haumcmiastrum katangense (S.Moore) P.A.Duvign. & Plancke

LAMIACEAE K-ZA-TZ-AO Paton & Brooks 1996

Barleria variabilis Oberm _{Barleria descampsii ACANTHACEAE K-ZA Balkwill & Balkwill 1997}

Becium aureoviride P.A. Duvign.

1

Ocimum vanderystii (De Wild.) AJ. Paton

LAMIACEAE K-ZA Paton 1995

Becium aureoviride ssp. lupotense P.A. Duvign. Ocimum vanderystii (De Wild.) A. J. Paton

LAMIACEAE K-ZA Paton 1995

Becium grandiflorum (Lam.) Pic. Ser. var. ericoides (P.ADuvign. & Plancke)

Ocimum monocotyloides (Ayobangira) A.J. Paton

LAMIACEAE K Paton 1995; Paton et al. 1999

Becium homblei (De Wild.) P.A. Duvign. & Plancke Becium centrali-ctfricanum (R.E. Fr.) Sebald

LAMIACEAE K-ZA-TZ Paton 1995

Becium kalangense Becium centrali-africanum (R.E. Fr.) Sebald

LAMIACEAE K-ZA-TZ Paton 1995

Becium metallorum P.A.Duvign. & Plancke Ocimum metallorum (P.A.Duvign. &