Taxonomic revision of the genus Bolusiella

Phytotaxa 114 (1): 1–22 (2013) www.mapress.com/ phytotaxa / Copyright © 2013 Magnolia Press

ISSN 1179-3155 (print edition)

Article

PHYTOTAXA ISSN 1179-3163 (online edition)

http://dx.doi.org/10.11646/phytotaxa.114.1.1

Taxonomic revision of the genus Bolusiella (Orchidaceae, Angraecinae) with a new species from Cameroon, Burundi and Rwanda SIMON VERLYNDE 1 , JEAN-YVES DUBUISSON 1 , TARIQ STÉVART 2 , 3 , 4 , MURIELLE SIMODROISSART 5 , DANIEL GEERINCK4 , BONAVENTURE SONKÉ2,5,6,7, VALÉRIE CAWOY 8, PASCAL DESCOURVIÈRES1 & VINCENT DROISSART2,3,5,6 1

UMR 7207 CNRS-MNHN-UPMC, Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, 57 rue Cuvier, CP 48, F-75005, Paris, France 2 Missouri Botanical Garden, Africa & Madagascar Department, P.O. Box 299, St. Louis, Missouri 63166-0299, USA 3 Herbarium et Bibliothèque de Botanique africaine, Université Libre de Bruxelles, campus de la Plaine, boulevard du Triomphe, CP 265, B-1050, Brussels, Belgium 4 National Botanic Garden of Belgium, Domein van Bouchout, Nieuwelaan 38, B-1860, Meise, Belgium 5 Plant Systematic and Ecology Laboratory, Higher Teacher’s Training College, University of Yaoundé I, Yaoundé, Cameroon 6 Institut de Recherche pour le Développement (IRD), Unité Mixte de Recherche AMAP (Botanique et Bioinformatique de l’Architecture des Plantes), Boulevard de la Lironde, TA A-51/PS2, F-34398, Montpellier Cedex 5, France; email: [email protected] 7 Evolutionary Biology and Ecology, Université Libre de Bruxelles, Av. F. Roosevelt, CP160/12, B-1050, Brussels, Belgium. 8 IGEAT-Institut de Gestion de l'Environnement et d'Aménagement du Territoire, Université Libre de Bruxelles, Avenue Antoine Depage, 13, B-1050, Brussels, Belgium

Abstract On basis of morphological analyses and field investigation, a revision of Bolusiella (Angraecinae; Orchidaceae) was undertaken. We examined 302 specimens from several main herbaria, and for each of the six taxa recognized we provide a morphological description, distribution, habitat, phenology and IUCN conservation status assessment. Distribution maps and an identification key are also provided. Detailed examinations of specimens and comparison with nomenclatural types resulted in one novelty, Bolusiella fractiflexa, which is distributed in lowland and montane forests of Cameroon, Burundi and Rwanda. This species is close to Bolusiella maudiae and B. talbotii in general aspect but differs from them in having only a small or absent spur and a basally fractiflex inflorescence. Some taxonomic changes are made: B. alinae is synonymous with B. talbotii, and B. batesii is lectotypified and considered synonymous with B. zenkeri. Two new records are provided: B. maudiae from Nigeria and B. zenkeri from Liberia.

Abstract (French) La révision du genre Bolusiella (Angraecinae; Orchidaceae) a été réalisée sur la base d’analyses morphologiques et de collectes effectuées sur le terrain. Nous avons examiné 302 spécimens provenant des principaux herbaria, et pour chacun des six taxons reconnus nous donnons une description morphologique, la distribution, l'habitat, la phénologie et l'évaluation du statut de conservation selon l'UICN. Des cartes de distribution et une clé d'identification sont également fournies. L'examen détaillé des spécimens et la comparaison avec les types nomenclaturaux ont permis la description d’un nouveau taxon, Bolusiella fractiflexa, qui est présent dans les forêts de plaine et de montagne du Cameroun, du Burundi et du Rwanda. Ce taxon est végétativement proche de Bolusiella maudiae et de B. talbotii, mais en diffère par des fleurs présentant un éperon court ou absent et par l'inflorescence à la base fractiflexe. Certains changements taxonomiques sont effectués: B. alinae est synonyme de B. talbotii; B. batesii est lectotypifié et est synonyme de B. zenkeri. Deux nouvelles signalisations sont données: B. maudiae au Nigeria et B. zenkeri au Liberia. Key words: Angraecoid orchids, epiphyte, IUCN Red List Categories and Criteria, taxonomy, tropical African flora

Accepted by Mark Chase: 30 May 2013; published online in PDF: 24 June 2013

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Introduction According to the World checklist of Orchidaceae (Govaerts et al. 2012), the genus Bolusiella Schlechter (1918: 105), known only from continental Africa, comprises seven taxa (six species and one subspecies). The genus has long been considered as a member of subtribe Aerangidinae until recent molecular studies show that this subtribe and Angraecinae are not natural, so now Bolusiella is considered a member of the later s.l. (Carlsward et al. 2006, Micheneau et al. 2008). Since its establishment by Schlechter (1918), no taxonomic revision for the genus has been published. The first Bolusiella species was published under the name Angraecum maudiae Bolus (1893: t. 9), now B. maudiae (Bolus) Schlechter (1918: 106). The following species were formerly described under the genus Listrostachys Reichenbach (1852: 930): L. zenkeri Kraenzlin (1894: 252), L. batesii Rolfe (1897: 167), L. iridifolia Rolfe (1897: 167) and L. imbricata Rolfe (1910: 161). Angraecum talbotii Rendle (1913: 108) was described from a specimen collected in Nigeria by Mr. and Mrs. Talbot. Then, Schlechter (1918) transferred Angraecum maudiae, Listrostachys batesii, L. imbricata, L. iridifolia and L. zenkeri to Bolusiella, which was named after Harry Bolus (1834–1911), a botanist, artist, businessman and philanthropist from South Africa. Later, Angraecum talbotii was also included in Bolusiella by Summerhayes (1936). Then, three new taxa were described: Bolusiella iridifolia subsp. picea Cribb (1977: 180), B. lebeliana Delepierre & Geerinck (1998: 135) and B. alinae Szlachetko (2001: 682). Finally, Rice (2005) designated B. maudiae as the type species of the genus. During a botanical survey conducted in 2008 in southern Cameroon, a living specimen without flowers of a Bolusiella was collected and initially thought to belong to an already known species. The plant was cultivated in the Yaoundé shadehouse, one of those in a system established in 1997 in central Africa (São Tomé, Gabon, Cameroon and Democratic Republic of Congo; Stévart 2003, Droissart 2009). Then, fertile and identifiable material of this specimen was obtained, and it appeared to possess a unique combination of floral characters not previously reported for the genus. Examination of literature, types and other specimens conserved in most of main herbaria holding African collections (BM, BR, BRLU, K, MA, MO, P, WAG and YA; herbarium acronyms according to Thiers 2013) confirmed our opinion and allowed us to identify other specimens from Burundi and Rwanda that correspond to the novelty described here. This revision is part of a large project focusing on the angraecoid orchids of the largely unexplored central portion of the Congo Basin. Recent fieldwork allowed us to collect several new specimens of Bolusiella preserved in spirit. This newly collected material as well as specimens examined in the main herbaria allowed us to solve several taxonomic problems within the genus and find new national records. This revision includes the description of a new species, synonymy of two additional names, conservation assessments and a taxonomic key for the six taxa recognized.

Material and methods The revision presented here is based on recent fieldwork (1997 to present) and examination of 302 herbarium specimens. Observations and measurements are mainly based on specimens recently collected in São Tomé, Cameroon, Equatorial Guinea and Gabon and deposited at BRLU, with most being preserved in spirit. Additional specimens from BM, BR, BRLU, K, MA, MO, P, WAG and YA were also examined. Dried material was boiled in water to facilitate stereomicroscopic observation. Morphological investigation used a Nikon SMZ645 stereomicroscope for both spirit-preserved material and herbarium sheets. Photographs of Bolusiella flowers were taken with a Canon EOS 600D camera mounted on a Zeiss stereomicroscope Stemi SV11. Pictures of the same flower taken at different focal lengths were assembled with CombineZ 5.3 software (Program by Alan Hadley, available at www.hadleyweb.pwp.blueyonder.co.uk). Measurements, colours and other details given in the descriptions are based on living material, spirit and herbarium specimens and data derived from field notes.

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Distribution was based on the World checklist of Orchidaceae (Govaerts et al. 2012). The distribution of each species was checked and in some cases improved by examination of specimens. The chorological distribution follows White (1979, 1983, 1993) but using his simplified categories (“regional (sub)centre of endemism” and other) of region and domain. The conservation status of each recognized species was assessed by applying the IUCN Red List Categories and Criteria (IUCN 2001). Georeferenced specimen data were imported into GIS to calculate area of occupancy (AOO) and extent of occurrence (EOO). The cell area was set such that the maximum AOO of a species known only from a single subpopulation does not exceed 10 km², the upper limit for Critically Endangered status (cell size = 3.16 × 3.16 km). Each subpopulation represents a locality where the species was collected. The number of locations is calculated with regard to distinct kinds of threats, which may involve merging adjacent subpopulations.

Taxonomic Treatment Bolusiella Schlechter (1918: 105). Type:—Bolusiella maudiae (Bolus) Schltr.

Monopodial plants, epiphytic or sometimes lithophytic. Habit psygmoid, leaves arranged in a plane, dorsoventrally flattened and unifacial. Flowers white, resupinate, 2–6 mm long with free tepals, disposed on a lateral inflorescence, more or less grouped, in a simple raceme. Lip triangular and sometimes slightly trilobate; spur conical or cylindrical; present in most species. Column anther bearing two pollinia on two mace-shaped stipes, linked by a diamond-shaped viscidium; stigma concave and separated from the pollinia by a tridentate rostellum, with the lateral lobes longer than the median lobe. Bolusiella is widely distributed in Sub-Saharan Africa (Fig. 1). The Lower Guinea Domain and the Afromontane Region (Kivu-Ruwenzori regional mountain system) represent the centres of diversity of the genus because four of the six recognized taxa occur in these phytochoria.

FIGURE 1. Species richness (number of taxa per 2.5° × 2.5° quadrat) of Bolusiella in Sub-Saharan Africa.

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Key to the species of Bolusiella: 1. 2. 3. 4. 5. -

Leaves not deeply sulcate on upper surface................................................................................................................. 2. Leaves deeply sulcate on upper surface....................................................................................................................... 5. Pouch-like outgrowth at the base of the lower sepals and floral bract as long as the flower .................................... 3. Base of the lower sepals without outgrowth and floral bract strictly smaller than the flower ................................... 4. Base of the inflorescence straight, spur 1.2 mm or longer ..........................................................................B. maudiae Base of the inflorescence fractiflex, spur up to 1.1 mm ............................................................................ B. fractiflexa Leaves with rounded apex ............................................................................................................................. B. zenkeri Leaves with acute apex .................................................................................................................................. B. talbotii Spur at right angle or partly curved under the lip, cylindrical, > 1mm ........................... B. iridifolia subsp. iridifolia Spur in the same plane as the lip, conical, < 1mm long ........................................................ B. iridifolia subsp. picea

1. Bolusiella maudiae (Bolus) Schltr. (Fig. 2D) Basionym: Angraecum maudiae Bolus. Type:—SOUTH AFRICA. Zululand: Etshowe, 21 March 1893, Saunders 6270 (holotype BOL, isotype K!). Heterotypic synonyms: Bolusiella imbricata (Rolfe, 1910: 161) Schlechter (1918: 106) ≡ Listrostachys imbricata Rolfe. Type: —GHANA. Without data: Anderson s.n. (holotype K).

Epiphytic herb with non-branching stem (2–20 mm) and 1–3 mm internodes. Leaves not deeply sulcate on upper surface, 15–30 × 5–10 mm, rounded at the apex. Inflorescences 31–65 mm long, 16–24 flowered, grouped in the apical half. Floral bracts brown, widely triangular, 3.5–7.0 × 2.9–5.0 mm, apex acuminate, sheathing, imbricate in the basal half of the inflorescence. Flowers 3.5–4.1 mm long and 1.2–2.1 mm diameter, 1 mm apart from each other. Dorsal sepal narrowly triangular, 2.8–3.0 × 0.7–1.0 mm. Lateral sepals narrowly triangular, 2.8–3.2 × 0.6–1.0 mm, carinate, with a basal pouch-like outgrowth. Petals ovoid, 2.0–2.7 × 0.6–1.0 mm. Lip triangular, 1.3–2.2 × 1.0–1.6 mm. Spur cylindrical, curved under the lip, 1.2–1.6 mm long, 0.4–0.5 mm diameter. Column 0.8–0.1 mm long. Ovary 0.8–1.6 mm long and 0.5–0.8 mm diameter. Chorology & distribution:—Widespread in Sub-Saharan Africa: Conakry Guinea, Ivory Coast, Ghana, Nigeria, Cameroon, Democratic Republic of Congo, Uganda, Kenya, Rwanda, Burundi, Tanzania, Zambia, Malawi and South Africa (Natal). This taxon is recorded here for the first time from Nigeria (Fig. 3). Habitat & ecology:—Epiphyte in humid and dense forests or in moderately disturbed forests, from 600 to 1,800 m. Flowering peaks in March, August–October and December. Conservation status:—IUCN Red List Category: Least Concern [LC]. The extent of occurrence (EOO) of B. maudiae is estimated to 8,052,650 km2 (far exceeding 20,000 km², the upper limit for Vulnerable status) and its area of occupancy (AOO) is about 160 km2 (which falls within the limits for Endangered status under criterion B2). The species is known from 16 subpopulations representing 12 different locations (i.e. greater than 10 locations, the upper limit for Vulnerable status under criterion B2). We are not aware of any current or projected extreme fluctuations in EOO, AOO, number of locations or subpopulations or number of mature individuals. Although its habitat might be threatened, B. maudiae does not appear as threatened according to the IUCN Red List criteria (IUCN 2001). We expect that human pressure will cause continuing loss of its habitat as well as its AOO but not a significant decrease of its number of subpopulations within the next decade. Etymology:—The name maudiae was given in honor of Mrs Emily Maud Eastwood Saunders, collector of the type. Discussion:—The name is often written as maudae in the literature and is used in some herbaria. In its protologue, Bolus (1893) indeed named the species Angraecum maudae in honor of Emily Maud Eastwood Saunders, the first spouse of Sir Charles James Renault Saunders. However, according to recommendation 60C.1(b) of the botanical nomenclatural code (McNeill et al. 2006), stating that «if the personal name ends with a consonant […] substantial epithets are formed by adding -i- (stem augmentation) plus the genitive inflection appropriate to the sex and number of the person(s) honoured (e.g. wilson-iae for Wilson (f))», and according to the article 60.11, the ending of the specific epithet is in contradiction with the recommendation developed above. Moreover, examples of other taxa dedicated to a woman surnamed Maud have been named maudiae, such as Michelia maudiae Dunn (1908: 23) and Phyllostachys maudiae Dunn (1912: 330). Angraecum maudae must therefore be corrected to Angraecum maudiae.

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FIGURE 2. Vegetative (upper) and floral (lower) morphology of Bolusiella species. A. Bolusiella zenkeri (Droissart et al. 765). B. Bolusiella iridifolia subsp. iridifolia (Stévart & Pial 282). C. Bolusiella iridifolia subsp. picea (Arbonnier 173). D. Bolusiella maudiae (Schaijes 1382). E. Bolusiella fractiflexa (Simo M. et al. (Ombrière de Yaoundé) 1357). F. Bolusiella talbotii (Ndong Bokung & Stévart 10). Square=1 mm2.



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FIGURE 3. Distribution of Bolusiella maudiae.

Additional specimens examined:—CONAKRY GUINEA. Mont Nimba: River Niaya, on the road to Serimbara, 30 June 2012, Stévart & Serein 4592 (MO). IVORY COAST. Abidjan: Banco Forest Reserve, Route Martineau, 1 km north of camp, left-hand side of road, 25 November 1975, de Koning 6170 (WAG); N'Douci à Agboville, 3 November 1974, Perez Vera 718 (P); Tiassalé, km 95 new road Abidjan-Ndouci, 1 October 1979, de Kruif 624 (WAG). GHANA. Near Apedwa, 8 October 1969, Hall, Agyakwah 39015 (P); Without locality information, 1 September 1952, Westwood 42 (K); without data, cult. Kew 8221 (K); without data, cult. Kew 12009 (K). NIGERIA. Without data, Cole s.n. (K); without data, cult. Kew 8217 (K). CAMEROON. Near Lakoti, Adamaoua, 11 March 1969, Sanford 6211 (K). DEMOCRATIC REPUBLIC OF CONGO. Route Tenke - Kando à 185 km au NO de Lubumbashi, 1,300 m, 26 October 1980, Schaijes 1382 (BR). UGANDA. Bunyoro District: Budongo forest, 1 August 1940, Eggeling 4045 (K, BR); Budongo forest, 914 m, 1940, Purseglove 986 (BR); Kabarole District, U2, Kibale Forest, Kanyawara, 1,450 m, 1997, Hafashimana 338 (K); Mabira Forest, 1,219 m, 1908, Brown s.n. (BM); Rukungiri District, U2, Kayonza, Bwindi forest, Ihihizo, 1,520 m, 1997, Hafashimana 694 (K); without locality information, 1 February 1943, Eggeling s.n. (K); without data, Leakey 4 (K); without data, Meyer K77 (K); without data, s.n. (K). KENYA. Kakamega forest, Near Forest Station, 1,550 m, 4 September 1986, Beentje 3081 (WAG); Kakamega forest, along road C39, 20km SE of Kakamega along Yala River, Tindinyo village, 1800 m, 23 August 1986, van der Laan 1245 (WAG); Kakamega forest, Esecheno, 30 metres from forester's house, 1,608 m, 28 March 2009, Miyawa, Muthoka, Gaya NMK1215 (K); Kakamega forest, 1,676 m, 10 December 1956, Verdcourt 1686 (BR); Nyanza province: north Kavirondo District, Kakamega forest station, 1,600 m, 17 September 1949, Maas 6263 (BR); without data, cult. Kew 3146 (K); without data, cult. Kew 10194 (K); without locality information, 29 August 1981, van der Laan 409 (WAG). BURUNDI. Vallée du Sanzu (Ruyigi), 6 December 1992, Arbonnier 366 (BR). TANZANIA. Without data, Moreau 75 (K); Lushoto District: 9.5 km E. of Amani, Sigi R., fl. cult., September 1944, Moreau 395 (K). ZAMBIA: without locality information, 23 April 1905, Bredo s.n. (K); without data, 11 October 1960, Holmes 31 (K). MALAWI. Without locality information, 7 March 1981, la Croix 114 (K). SOUTH AFRICA. Kwazulu-Natal: Eshowe, 9 June 1983, van der Laan 628 (WAG). EAST TROPICAL AFRICA: without locality information, 28 August 1963, Jackson 3 (K); without data, Jackson 7 (K).

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2. Bolusiella fractiflexa Droissart, Stévart & Verlynde, sp. nov. (Figs. 2E, 4) Type:—CAMEROON. Bindem (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 2°41’26.9’’ N, 10°47’31.5’’ E, 532 m, 24 September 2008, Simo M. et al. (ombrière de Yaoundé) 1357 (holotype BRLU!, isotype YA!). Bolusiella fractiflexa Droissart, Stévart & Verlynde sp. nov., close to B. maudiae Schltr. and B. talbotii (Rendle) Summerhayes in the general aspect of the plant but differs from them in having only a small or absent spur and a basally fractiflex inflorescence

FIGURE 4. Bolusiella fractiflexa. A. Plant habit. B. Flower. C. Lip. D. (left to right) Lateral sepal, petal, dorsal sepal. Bars. 1 cm (A); 1 mm (B, C & D). (Drawing of the type specimen, Simo M. et al. 1357, by V. Cawoy.)



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Epiphytic herb with non-branching stem, 4–5 mm and 1 mm internodes. Leaves not deeply sulcate on upper surface, 15–20 × 4–5 mm, pointed at apex. Inflorescences 28–36 mm long, with a fractiflex base, 6–9 flowered, clustered at apex (10 mm long). Floral bract black, triangular, larger than flowers, 4.0–5.0 × 2.4–2.8 mm with an acuminate apex, sheathing, imbricate in the sterile portion of the inflorescence. Flowers 2.5–3.2 mm long, 1–2 mm diameter, 1 mm apart from each other. Dorsal sepal triangular, 1.8–2.8 × 0.9–1.0 mm. Lateral sepals triangular, 1.9–2.4 × 0.7–1.2 mm, carinate, with a basal pouch-like outgrowth. Petals triangular, 1.3–2.0 × 1.0 mm. Lip broadly triangular, 1.1–1.8 × 1.0–1.2 mm. Spur conical, short, 1.1 mm long, 0.6 mm diameter or almost absent in the Cameroon specimens. Column 0.4–0.8 mm long. Ovary 1.0–1.6 mm long and 0.5–0.8 mm in diameter. Chorology & distribution:—Lower Guinea Domain and Afromontane Region (Kivu-Ruwenzori regional mountain system): Cameroon, Burundi and Rwanda (Fig. 5).

FIGURE 5. Distribution of Bolusiella fractiflexa.

Habitat & ecology:—Epiphyte. In Cameroon, living specimens were collected on fallen branches of 8– 10 cm diameter, in lowland semi-deciduous forests under partial cultivation (banana and cocoa plantations). In Rwanda, the species was collected in montane forest with Parinari excelsa Sabine (1824: 451) and Syzygium guineense (Willd.) de Candolle (1828: 259). Flowering peak in September. Conservation status:—IUCN Red List Category: Endangered [EN B2ab(i,ii,iii)]. The extent of occurrence (EOO) of Bolusiella fractiflexa is estimated to 71,147 km2 (exceeding 20,000 km2, the upper limit for Vulnerable status) and its area of occupancy (AOO) is about 30 km2 (which falls within the limits for Endangered status under criterion B2). The species is known from three subpopulations representing three locations (i.e. less than five locations, the upper limit for Endangered status under criterion B2). The distribution of B. fractiflexa is extremely fragmented, explaining the large EOO obtained. In Cameroon, the species is only known from one living specimen collected in Bindem, a small village near the border of the Campo Ma’an National Park. There, we collected it in disturbed forest with cocoa and banana plantations. New searches are needed within the park to collect it in habitat less disturbed by human activities. The specimen

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collected in Bindem was cultivated in the Yaoundé shadehouse and produced two fertile specimens (Simo M. et al. (ombrière de Yaoundé) 1357, 2389) before it died. In the Albertin Rift (Burundi and Rwanda), the species is known from two subpopulations, one of which occurs within the protected part of the Nyungwe National Park. Etymology:—The specific epithet refers to the shape of the basal part of the inflorescence that represents a diagnostic character of the species. Discussion:—This species is morphologically similar to B. maudiae and B. talbotii (Rendle, 1913: 108) Summerh. in Hutchinson & Dalziel (1936: 456) in its floral and vegetative features. It differs from B. maudiae in the shape of its leaves, which do not have a rounded apex, and it differs from B. talbotii in its fleshier leaves. In addition, the sinuate shape of the basal part of the inflorescence and reduced or absent spur easily distinguish it from both other species (Table 1). According to unpublished molecular data produced by the first author, using plastid matK and ycf1 markers, this species is related to Bolusiella maudiae. Regarding the broad ecological range of the new taxa, the isolation between the two populations, from Cameroon and Burundi/Rwanda is more probably due to a sampling bias than to a long-distance seed dispersal event. Bolusiella are small epiphytic plants and difficult to observe and collect in the field. Moreover, the gap between those two populations (the Congo Basin) represents a poorly sampled zone. Additional specimens examined:—CAMEROON. Bindem, (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 532 m, 17 September 2010, Simo M. et al. (Ombrière de Yaoundé) 2389 (BRLU). BURUNDI. Cascade de Nyabihondo, 30 January 1992, Arbonnier 298 (BR). RWANDA. Préfecture de Cyangungu, commune de Kirambo, forêt de Uwinka, 2,150 m, 7 April 2000, Ewango 2242 (BR); Route Nyungwe, 2,053 m, s.d., Delepierre 173 (BR); Nyungwe, km 99, 18 September 2006, Delepierre 216 (BR). 3. Bolusiella zenkeri (Kraenzl.) Schlechter (1918: 106). (Fig. 2A) Basionym: Listrostachys zenkeri Kraenzlin (1894: 252). Type:—CAMEROON. Yaoundé, Zenker 623 (holotype B, lost?) and Bipindi, Zenker 3356b (neotype Z; isonéotype BM!, here designated but listed by Kraenzlin). Homotypic synonyms: Angraecum zenkeri (Kraenzl.) Engler in Engler & Drude (1908: 421) comb. illeg. ≡ Angraecum zenkeri (Kraenzl.) Schlechter (1900: 285) Heterotypic synonym: Bolusiella batesii (Rolfe) Schlechter (1918: 106) ≡ Listrostachys batesii Rolfe (1897: 167). Type:—CAMEROON. Efulen, 20 September 1895, Bates 381 (lectotype K!, isolectotype BM!, here designated). syn. nov.

Epiphytic herb with non-branching stem, 12–15 mm long, and internodes1–4 mm long. Leaves not deeply sulcate on upper surface, 32–65 × 6–8 mm, acinaciform, rounded at the apex. Inflorescence 44(18)–91(211) mm long, 5–23 flowered. Floral bracts brown, widely triangular, smaller than flowers, 1.5–2.3 × 1.4–3.2 mm, with an acuminate apex, sheathing, not imbricate in the sterile portion of the inflorescence. Flowers 4.3–6.0 mm long, 3.1–5.2 mm diameter, 1–2 mm apart from each other. Dorsal sepal narrowly triangular, 3.0–5.0 × 1.1–1.8 mm. Lateral sepals narrowly triangular, 3.3–5.0 × 1.0–1.8 mm, carinate. Petals triangular, 2.4–4.1 × 1.1–2.0 mm, slightly carinate. Lip narrowly triangular, 2.4–3.9 × 1.0–1.2 mm. Spur cylindrical, with a right angle to partially curled under the lip, 1.8–3.0 mm long, 0.5–1.0 mm diameter. Column 1.1–2.1 mm long. Ovary 1.1–2.0 mm long, 0.7–1.0 mm diameter. Chorology & distribution:—Upper and Lower Guinea Domains: Liberia, Ivory Coast, Ghana, Cameroon, Equatorial Guinea (Bioko and Rio Muni), Gabon and Republic of Congo. This taxon is recorded here from Liberia for the first time (Fig. 6). Habitat & ecology:—Epiphyte in humid forests, secondary humid forests and plantations of cocoa and coffee. This species is found from 100–1,000 m elevation. Flowering peaks in March, August–October and December. Conservation status:—IUCN Red List Category: Least Concern [LC]. The extent of occurrence (EOO) of Bolusiella zenkeri is estimated to 1,015,870 km2 (far exceeding 20,000 km2, the upper limit for Vulnerable status), and its area of occupancy (AOO) is about 450 km2 (which falls within the limits for Endangered status under criterion B2). The species is known from 45 subpopulations representing more than 10 locations, the upper limit for Vulnerable status under criterion B2. We are not aware of any current or projected extreme TAXONOMIC REVISION OF THE GENUS BOLUSIELLA


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fluctuations in EOO, AOO, number of locations or subpopulations, or number of mature individuals. Although its habitat may be locally threatened by deforestation, B. zenkeri does not appear as threatened according to the IUCN Red List criteria (IUCN 2001). We expect that human pressure will increase the loss of its habitat as well as its AOO but not a significant decrease of its number of subpopulations within the next decade.

FIGURE 6. Distribution of Bolusiella zenkeri.

Etymology:—The species is dedicated to Georg August Zenker, collector of the type species. Discussion:—Kraenzlin described Listrostachys zenkeri in 1894 with only the specimen Zenker 623, which is then automatically the holotype. In 1900, Schlechter published the name Angraecum zenkeri, citing two specimens (Schlechter 12745, 12900), which is considered as a legitimate combination according to ICBN Article 41.5. This renders the combination of Engler (1908) illegitimate. In 1915, Kraenzlin (1915: 395) amended the description of Listrostachys zenkeri and cited Zenker 3356 as a new specimen, stating that this specimen better represented his taxon than Zenker 623. In 1918, he transferred Listrostachys zenkeri to Bolusiella without citing any specimens, but citing A. zenkeri as a synonym. Despite intensive search in main herbaria (BM, BR, BRLU, K, MA, P, WAG and YA), the type specimen, Zenker 623 and Schlechter 12900 have not been found. We therefore suspect that they were destroyed during the Second World War in 1943 in the burning of Berlin Herbarium. We have seen the specimen Schlechter 12745 at BR and K, and it corresponds to Bolusiella iridifolia subsp. iridifolia. We also have found that Zenker 3356 (M, http:// plants.jstor.org/specimen/m0103355) was not Bolusiella zenkeri, but instead Listrostachys pertusa. However, Z e n k e r 3 3 5 6 b d e p o s i t e d i n Z u r i c h ( h t t p : / / w w w. h e r b a r i e n . u z h . c h / s t a t i c / d a t a b a s e / details_en.php?&spTypFlg=&spBarCod=Z-000019002&spHer=) has been examined, and it was clearly identified by Kraenzlin in 1913 as Bolusiella zenkeri. Thus, there is no doubt that a typographical error occurred when Kraenzlin published the amended description. Since Zenker 3356b was considered by Kraenzlin as B. zenkeri, we therefore designated it as the neotype of this taxon. We also have examined a duplicate of Zenker 3356b deposited at the Natural History Museum in London (BM), and it shows no differences from B. batesii. Moreover, our recent and intensive fieldwork in the Bipindi

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area in Cameroon resulted in collection of specimens of B. batesii, which is frequent in this area. In conclusion, we have no doubt that B. batesii has to be considered as synonym of B. zenkeri because of priority of the latter. Finally, in the protologue of Listrostachys batesii, two syntypes were cited by Rolfe (1897), Bates 381, Efulen, Cameroon and Bates 463, river Como, Gabon. In the Kew herbarium catalogue (http://apps.kew.org/ herbcat/), Bates 381 is indeed proposed for Bolusiella batesii whereas Bates 463 is identified as Hetaeria mannii Bentham ex Durand & Schinz (1894: 57). Moreover, this specimen, Bates 463, before being identified as H. mannii, was identified as Zeuxine batesii Rolfe (1897: 182). Finally, in the protologue of Z. batesii two specimens are cited, one being Bates 463. Thus, association of Bates 463 with Listrostachys batesii is an error, the specific epithet being the same. Therefore, we cannot keep two syntypes for L. batesii, but only one (Bates 381), which is thus lectotypified. Additional specimens examined:—LIBERIA. Without data (spirit collection K). IVORY COAST. Rocher de Braforiedi, 28 October 1957, Aké Assi 4437 (K); Brafouéby, 1 October 1973, Perez Vera 539 (P); Forêt de Taï, 22 October 1961, Aké Assi 6034 (K); Mont Mafa, 14 March 1967, Aké Assi 9541 (K); Forêt de Soubré (oct. 71), en culture à Daloa, 3 December 1974, Perez Vera 194 (K); Sassandra, 8 km S of LagakoTokpeko on the road to Port-Gauthier, 24 November 1975, de Koning 6168 (WAG); Sassandra, Béyo, c. 60 km N of Sassandra, left bank of Davo River, E of Béyo, 100 m, 27 January 1959, Leeuwenberg 2595 (WAG); Sassandra, 8 km S. of Lagako-Tokpeko on the road to Port-Gauthier, 6 March 1978, van Setten 111 (WAG); Région de Youkon, S de la région du Nimba, 1 August 1942, Schnell 1689 (P); s.l., 28 April 1983, van der Laan 603 (WAG). GHANA. Central Province: Asuansi, near Cape Coast, 1954, Benton, Westwood 162 (K); Jarkua, November 1941, Vigne 1941 (K). CAMEROON. Abam to Ebolowa, 1 March 1969, Sanford 6112 (K); Akom II, (route Kribi-Ebolowa), 710 m, 13 September 2008, Simo M. et al. (Ombrière de Yaoundé) 1297 (BRLU); Akom II (route Kribi-Ebolowa), 710 m, 15 September 2010, Simo M. et al. (Ombrière de Yaoundé) 2371 (YA); Akom II, (Est de Kribi), 400 m, 24 September 2008, Simo M. et al. (Ombrière de Yaoundé) 1340 (BRLU); Akom II (Est de Kribi), 400 m, 11 September 2009, Simo M. et al. (Ombrière de Yaoundé) 1787 (BRLU); Akom II (Est de Kribi), 400 m, 07 October 2010, Simo M. et al. (Ombrière de Yaoundé) 2442 (YA); Sanctuaire de Banyang Mbo, Village de Bejange, situé à l'extrême S de la réserve, 510 m, 10 October 2008, Simo M. et al. (Ombrière de Yaoundé) 1378 (BRLU); Sanctuaire de Banyang Mbo, Village de Bejange, situé à l'extrême S de la réserve, 510 m, 08 October 2009, Simo M. et al. (Ombrière de Yaoundé) 1863 (YA); Bidjouka, (Massif de Ngovayang), 465 m, 13 June 2006, Droissart 141 (BRLU); Bidjouka, (Massif de Ngovayang), 585 m, 17 June 2006, Droissart 163 (BRLU); Bidjouka, (Massif de Ngovayang), 585 m, 03 September 2007, Droissart et al. (Ombrière de Yaoundé) 692 (YA); Bidjouka, (Massif de Ngovayang), 105 m, 19 September 2008, Simo M. et al. (Ombrière de Yaoundé) 1308 (BRLU); Bindem, (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 585 m, 11 May 2007, Droissart 535 (BRLU); Bindem, (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 570 m, 15 September 2006, Droissart et al. (Ombrière de Yaoundé) 427 (BRLU); Bindem, (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 570 m, 30 August 2007, Droissart et al. (Ombrière de Yaoundé) 677 (YA); Bindem, (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 595 m, 04 September 2007, Droissart et al. (Ombrière de Yaoundé) 702 (BRLU); Bindem (route allant vers Messama, perpendiculaire à la route KribiEbolowa), 590 m, 19 September 2007, Droissart et al. (Ombrière de Yaoundé) 743 (BRLU); Bindem (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 570 m, 07 September 2008, Simo M. et al. (Ombrière de Yaoundé) 1278 (BRLU); Bindem, (route allant vers Messama, perpendiculaire à la route KribiEbolowa), 570 m, 08 September 2009, Simo M. et al. (Ombrière de Yaoundé) 1769 (BRLU); Bindem, (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 570 m, 07 September 2010, Simo M. et al. (Ombrière de Yaoundé) 2341 (YA); Bindem, (route allant vers Messama, perpendiculaire à la route KribiEbolowa), 570 m, 17 September 2010, Simo M. et al. (Ombrière de Yaoundé) 2390 (BRLU); Bindem, (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 570 m, 27 September 2011, Simo M. et al. (Ombrière de Yaoundé) 3175 (YA); Bindem, (route allant vers Messama, perpendiculaire à la route KribiEbolowa), 532 m, 15 September 2010, Simo M. et al. (Ombrière de Yaoundé) 2370 (BRLU); Memel II au N de TAXONOMIC REVISION OF THE GENUS BOLUSIELLA


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Bipindi, 140 m, 06 September 2004, Droissart et al. (Ombrière de Yaoundé) 95 (BRLU); Colline de Nkoltsia, 23km au NO de Bipindi, 23 March 1974, Villiers 827 (YA); Bipindi, s.d., Zenker 3396b (BM); Dja, 03 September 2007, Droissart et al. (Ombrière de Yaoundé) 690 (BRLU); Dja, Djomedjo-Nemeyong II, 500 à 600 m, 04 October 2004, Droissart et al. (Ombrière de Yaoundé) 147 (BRLU); Dja, Piste de Kougoulou à Nkoubar (rocher de), 27 September 2007, Droissart et al. (Ombrière de Yaoundé) 765 (BRLU); Dja, Bali (saline de), 550 m, 5 September 2002, Stévart & Pial 614 (BRLU); Dja : Chutes Mbolo, S de la Réserve du Dja, (N de Djoum, 515 m, 2 September 2003, Stévart & Pial 883 (BRLU); Central Province, 45 km West of Yaoundé, 700 m, 1964, Atwell 20 (WAG); Central Province, Akouandoué, Nkolbisson near Yaoundé, 28 December 1981, van der Laan 461 (WAG); Ebolowa, Station du cacaoyer de N'Koemvone, 14 km on the road to Ambam, 570 m, 27 August 1974, van der Burg 7416 (K, WAG, YA); Inselberg d'Akookas, 38 km au SE d'Ebolowa, 700 m, 15 March 2001, Parmentier & Kouob 1839 (BRLU); Inselberg d'Akookas, 38 km au SE d'Ebolowa, 15 March 2001, Parmentier & Kouob 2129 (BRLU); Mbam-Minkom, (région de, au NO de Yaoundé), 815 m, 27 September 2007, Droissart et al. (Ombrière de Yaoundé) 762 (BRLU); Mbam-Minkom, (région de, au NO de Yaoundé, 880 m, 30 August 2008, Simo M. et al. (Ombrière de Yaoundé) 1248 (BRLU); Forêt entre Mintom et Lélé, 617 m, 09 September 2011, Simo M. et al. (Ombrière de Yaoundé) 3121 (BRLU); Rhumpi Hills, Small Massaka, 971 m, 25 October 2010, Simo M. et al. (Ombrière de Yaoundé) 2499 (BRLU); Rhumpi Hills, Small Massaka, 971 m, 21 October 2011, Simo M. et al. (Ombrière de Yaoundé) 3233 (YA); Somalomo village, plantation de café, 650 m, 4 October 2001, Stévart & Pial 240 (BRLU); Somalomo village, 650 m, 12 October 2001, Stévart & Pial 247 (BRLU); near Yaoundé, 20 miles on Douala road, 2 November 1968, Sanford 5312 (P, K, YA); near Yaoundé, 16 miles toward Douala, near village Ongot, 7 November 1968, Sanford 5326 (K). EQUATORIAL GUINEA. Rio Muni, Avelemang, 520 m, 18 January 2003, Deman 270 (BRLU); Rio Muni, Bikaba (route de Monte Alén à Niefang), 550 m, 6 October 1999, Ndong Bokung & Stévart 92 (BRLU); Rio Muni, just on the Bata side of Niefang, 396 m, 13 February 1969, Sanford 5750 (K); Rio Muni, near Niefang, Ebebiyin side, 87 miles from Ebebiyin, 396 m, 13 February 1969, Sanford 5756 (K). GABON. Koum (Mont), 1 km du village de Kumassi, à 32 km d'Oyem vers Bitam, 655 m, 14 April 2002, Stévart 1315 (BRLU); Miwa (Mont), 3 km du village de Kumassi, à 32 km d'Oyem vers Bitam, à coté du Mont Koum, 635 m, 28 August 2002, Stévart 1855 (BRLU); Miwa (Mont), 3 km du village de Kumassi, à 32 km d'Oyem vers Bitam, à coté du Mont Koum, 635 m, 24 September 2002, Stévart 1856 (BRLU); Ngounié, Massif de Koumounabouali, 420 m, 8 December 1996, de Wilde 11684 (WAG). 4. Bolusiella talbotii (Rendle) Summerhayes in Hutchinson & Dalziel (1936: 456). (Fig. 2F) Basionym: Angraecum talbotii Rendle (1913: 108). Type:—NIGERIA. Oban, 1911, Talbot 941 (holotype BM!, drawing K!). Heterotypic synonyms: Bolusiella alinae Szlachetko (2001: 682). Type:—EQUATORIAL GUINEA (BIOKO). Region Sta. Isabel to San Carlos, km 42, off road towards sea close to Playa Alena, 18 February 1969, Sanford 5919 (holotype P, isotype K!). syn. nov.

Epiphytic herb with non-branching stems, 2–15 mm long, internodes 0.5–5.0 mm long. Leaves not deeply sulcate on upper surface, 15–44 × 0.5–7 mm, with an acute apex. Inflorescences 11–110 mm long, 2–22 flowered. Floral bracts triangular, 1.7–3.1 × 1.3–2.2 mm, smaller than flowers, apex acuminate, brown, sheathing, and not imbricate in the sterile portion of the inflorescence. Flowers 3.0–5.1 mm long and 2.0–3.5 mm diameter, 1–3 mm apart from one another. Dorsal sepal narrowly triangular, 1.7–4.0 × 0.9–1.2 mm. Lateral sepals triangular, 2.0–4.0 × 0.8–1.3 mm, carinate. Petals triangular, 1.7–3.3 × 0.8–1.3 mm. Lip partially trilobed, 1.6–3.0 mm × 0.9–1.5 mm. Spur cylindrical or conical, at a right angle with the lip, 1.3–2.3 mm long and 0.5–1.0 mm diameter. Column 0.6–1.2 mm long. Ovary, 1.0–1.4 mm long, 0.5–0.8 mm diameter. Chorology & distribution:—Widespread in tropical Africa: Guinea Conakry, Sierra Leone, Liberia, Ivory Coast, Ghana, Togo, Nigeria, São Tomé & Príncipe, Cameroon, Equatorial Guinea (Annobón, Bioko, Rio Muni), Gabon, Republic of Congo, Rwanda and Tanzania (Fig. 7).

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FIGURE 7. Distribution of Bolusiella talbotii.

Habitat & ecology:—Epiphyte in dense humid forests, river banks, inselbergs, undisturbed to disturbed areas and sometimes in direct sunlight. This species is found from 100–500 m elevation. Flowering peaks in January–March and May–November. Conservation status:—IUCN Red List Category: Least Concern [LC]. The extent of occurrence (EOO) of B. talbotii is estimated to 5,857,850 km2 (far exceeding 20,000 km2, the upper limit for Vulnerable status), and its area of occupancy (AOO) is about 490 km2 (which falls within the limits for Endangered status under criterion B2). The species is known from 49 subpopulations representing more than 10 locations, the upper limit for Vulnerable status under criterion B2. We are not aware of any current or projected extreme fluctuations in EOO, AOO, number of locations or subpopulations, or number of mature individuals. Although its habitat might be threatened, B. talbotii does not appear as threatened according to the IUCN Red List criteria (IUCN 2001). We expect that the human pressure will decrease the available habitat as well as its AOO without a significant decrease of its number of subpopulations within the next decade. Etymology:—Rendle (1913) named this species in honor of collectors of the type, Mr and Mrs P.A. Talbot. Discussion:—The drawings accompanying the protologue of Bolusiella alinae do not correspond to the isotype (Sanford 5919) found at K; the main diagnostic character for B. alinae, a spur curled at the back of the flower, was not observed on this specimen. Moreover, we also observed such ‘curling’ on flowers of other samples of B. talbotii, which results from the position of the spur along the peduncle. This can be explained by an abnormal development of the flower, with a spur compressed by the floral bract. Bolusiella alinae is thus considered as a synonym of B. talbotii. The holotype in P has unfortunately not been found, has not been digitized and is indicated as “on loan” on the online collections (http://coldb.mnhn.fr/). Additional specimens examined:—GUINEA CONAKRY. Guinea Forestière: Nimba Mountains, Rivière Zié, In gallery forest along the river, on a Carapa, 10 October 2011, Stévart et al. 4085 (MO); Nimba Mountains, à 400 m de la station de pompage de la Zié, 10 October 2011, Stévart et al. 4092 (MO); Rivière Mamou, 1 December 1906, Pobéguin 1450 ter. (P). SIERRA LEONE. Région du Da-Gulua: Monts Loma, 1 TAXONOMIC REVISION OF THE GENUS BOLUSIELLA


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September 1945, Jaeger 1377 (P, K); Makump, N. Province, 22 August 1928, Deighton 1436 (BM, K); Kailahun District: Woroma, in forest, 11 July 1982, Segerback 1529 (K). LIBERIA. Ganta from Gowi, 25 July 1951, Harley 1818 (K); Mount Bele Road, 500 m, 29 August 1964, Adames 462 (K); Nimba Mounts, Yekepa, 500 m, 17 July 1968, Johansson 438 (K); Nimba Mounts, Near Iron Mine of L.A.M.C.O., 500 m, 25 July 1965, Leeuwenberg & Voorhoeve 4615 (WAG); Nimba Mounts, near Iron Mine of L.A.M.C.O., 400 m, 29 July 1965, Leeuwenberg & Voorhoeve 4686 (WAG); Sinoe Co., Kulo, 13 March 1948, Baldwin 11421 (K); Western Province: Kolahum District, Kailahum, 4 November 1947, Baldwin 10139 (K); s.l., November 1931, Harley 1767 (K). IVORY COAST. Abidjan, Banco Forest Reserve, Banco Nat. Park, along a track and a river, north of Banco, 28 March 1972, van Doorn 162 (WAG); Banco Forest Reserve, 1975, van der Burg 658 (WAG); Sassandra (56 km N of), E of Béyo, 90 m, 3 July 1962, Leeuwenberg 4561 (WAG); Forêt de Yapo, 26 October 1974, Perez Vera 737 (P, K). GHANA. Asuansi, Central Province, near Cape Coast, 7 May 1905, Benton & Westwood 162A (K); Botanical station Aburi, s.d., Johnson 4 (K); Tarkwa, Novembre 1941, Vigne 4809A (K); Without locality information, 2 July 1945, Cox 121 (K). TOGO. Badou-Tomegbe road, 792 m, 23 September 1967, Bowling, Seku GC36602 (K). SÃO TOMÉ ET PRÍNCIPE. Príncipe : Principe Pico papagaio , 680 m, 20 August 2002, Primo & Stévart 77 (BRLU); Príncipe : Without data, Stévart 432 (K); São Tomé : Estação Souza, 1,500 m, 11 October 1997, Stévart 276 (BRLU); São Tomé : Estacao Souza, 1,500 m, 1 July 1998, Stévart 510 (BRLU); São Tomé : Nova ceilao, 900 m, 1 November 1998, Stévart 459 (BRLU); São Tomé : Chemin du Pico de Principe (première crête), 500 m, 1 November 1998, Stévart 432 (BRLU). CAMEROON. Akom II, (Est de Kribi), 620 m, 23 July 2006, Droissart et al. (Ombrière de Yaoundé) 401 (BRLU); Akom II (route Kribi-Ebolowa), 710 m, 20 August 2007, Droissart et al. (Ombrière de Yaoundé) 658 (BRLU); Akom II, (Est de Kribi), 880 m, 6 March 2004, Stévart & Droissart 2065 (BRLU); Akom II, (Est de Kribi), 1,035 m, 7 March 2004, Stévart & Droissart 2104 (BRLU); Bidou III/Nkolembonda (route Kribi-Ebolowa), pied du Mt des Éléphants, Bidou III à HEVECAM, versant E, 445 m, 07 September 2008, Simo M. et al. (Ombrière de Yaoundé) 1280 (BRLU); Bindem (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 570 m, 12 May 2007, Droissart 540 (BRLU); Bindem (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 570 m, 27 July 2007, Droissart et al. (Ombrière de Yaoundé) 621 (YA); Bindem (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 570 m, 26 August 2008, Simo M. et al. (Ombrière de Yaoundé) 1228 (BRLU); Bindem (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 570 m, 18 August 2009, Simo M. et al. (Ombrière de Yaoundé) 1715 (YA); Bindem (route allant vers Messama, perpendiculaire à la route Kribi-Ebolowa), 570 m, 23 August 2010, Simo M. et al. (Ombrière de Yaoundé) 2303 (BRLU); Bindem (route allant vers Messama, perpendiculaire à la route KribiEbolowa), 570 m, 01 September 2011, Simo M. et al. (Ombrière de Yaoundé) 3082 (YA); Mt Kupe, village de Nyasoso, 869 m, 21 October 2009, Droissart & Stévart 698 (BRLU); Littoral Province, Forêt de Bakaka, 3 km E. of Eboné, 520 m, 30 October 1971, Leeuwenberg 8651 (WAG); Mama (campement et plantation près de Etou), axe Somalomo-Ekom et Mbassakok (inselberg de), 595 m, 17 June 2002, Stévart & Pial 364 (BRLU); Mbam-Minkom (région de, au NO de Yaoundé), village de Nye-Meyong, 1,120 m, 11 May 2006, Droissart 24 (BRLU); Mbam-Minkom (région de, au NO de Yaoundé), village de Nye-Meyong, 1,100 m, 15 May 2006, Droissart 83 (BRLU). EQUATORIAL GUINEA. Annonbon : Ridge west of Crater Lake, 519 m, 14 July 1959, Wrigley 33 (P, K, BR); Bioko : Between Parador and Malsa, 5 January 1967, Sanford 4310 (K); Bioko: Near Playa Alena, off km 42 San Carlos area, 18 February 1969, Sanford 5920 (P, K); Rio Muni: inselberg de Akoak Ebanga, à 1h de marche du village de Ngong Mocomo, à 10 km de Nsork, 570 m, 31 May 2002, Parmentier & Esono 3517 (BRLU); Cataratas, grande chute, 250 m, 24 June 2000, Ndong Bokung & Stévart 182 (BRLU); Engong, Parc Nat. de Monte Alen, 5 km au NO de Engong, inselberg, 1,120 m, 3 January 1999, Lejoly 143 (BRLU); Engong, Parc Nat. de Monte Alen, 5 km au NO de Engong, inselberg, 1 August 1999, Ndong Bokung & Stévart 10 (BRLU); Engong, Parc Nat. de Monte Alen, 5 km au NO de Engong, inselberg, 1,200 m, 3 September 1999, Ndong Bokung & Stévart 52 (BRLU); Inselberg d'Engong, 14 August 2001, Ndong Bokung & Stévart 400 (BRLU); Inselberg d'Engong, 11 September 2001, Ndong Bokung & Stévart 417 (BRLU); Engong, (Parc Nat. de Monte Alén), dalle rocheuse (inselberg) d'Engong, à 5 km au NO du Village d'Engong, 1,100 m, 21 July 2001, Ndong Bokung, Stévart & Obama 364 (BRLU); Engong,

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1,200 m, 1 July 1999, Stévart 560 (BRLU); Engong, (Parc Nat. de Monte Alén), dalle rocheuse (inselberg) d'Engong, à 5 km au NO du Village d'Engong, 1,100 m, 20 July 2001, Stévart 1035 (BRLU); Engong, (Parc Nat. de Monte Alén), dalle rocheuse (inselberg) d'Engong, à 5 km au NO du Village d'Engong, 1,100 m, 20 July 2001, Stévart 1044 (BRLU); Centro Sur, Parque Nacional de Monte Alén, Misergue, senda hacia el río Laña, 14 May 1999, Pérez Viso 1166 (MA); Near village Mboma, 8 miles off main road to Rio Benito, 26 February 1969, Sanford 6089 (K); Mungum (inselberg de), à 45 minutes de marche du village de Kukumancoc, 745 m, 24 May 2002, Stévart, Ndong Bokung & Ndong Maye 1544 (BRLU). GABON. Estuaire: Crystal Mountains, Mytsibé river, an affluent of the Zang River, just east of Méla, 300 m, 3 June 1983, van der Laan 622 (WAG); Crystal Mountains, 650 m, 6 June 1983, van der Laan 627 (WAG); Ngounié: Massif du Chaillu, 25 km along the road Mbigou - Mimongo, 650 m, 28 April 1983, van der Laan 601 (WAG); Ogooué-Ivindo: Babièl-Nord, eastern escarpment, 4 km from camp Bélinga, 800–900 m, October 1987, Louis, Sterck & Elias 2317 (WAG); Tchimbélé (carrière de) près du bras mort du lac, 570 m, 16 September 2002, Stévart 1770 (BRLU); Tchimbélé: chemin vers la carrière le long du bras mort, 570 m, 1 July 2001, Stévart Ngok Banak, Miko 1136 (BRLU); chemin vers la carrière le long du bras mort, 570 m, 8 September 2001, Stévart, Ngok Banak & Mendu 1137 (BRLU); (carrière de) près du bras mort du lac, 570 m, 1 July 2001, Stévart, Ngok Banak & Miko 1132 (BRLU); Woleu-Ntem: Inselberg, ca 25 km ESE of Medouneu, 500 m, 4 February 1986, Reitsma, Reitsma & Louis 1841 (WAG); Biteau O viii (K). REPUBLIC OF CONGO. Dimonika (Mayombe), 400 m, 11 November 1992, la Croix & la Croix 1133 (K); s.l., 11 December 1895, Lecomte s.n. (P). TANZANIA. Lushoto District: E. Usambara Mts., Amani, by rest house T3, 914 m, 18 January 1976, Cribb & Grey-Wilson 10262 (K); Amani, Tanga, behind Malaria Centre Amani, 880 m, 5 September 1986, van der Laan 1296 (WAG); E. Usambaras Mts., Amani, 914 m, April 1941, Moreau 41 (K); Iringa District: Mufindi, Lulando F., 1,500 m, 10 June 1905, fl. cult. February 1988, de Leyser 209 (K); Ulanga District: Sali, Muhulu Forest Reserve, 1,350 m, 24 January 1979, Cribb, Grey-Wilson & Mwasumbi 11186 (K); without locality information, 2 March 1993, Congdon 338 (K); without data, Trussell s.n. (K). 5. Bolusiella iridifolia (Rolfe) Schlechter (1918: 106). Basionym: Listrostachys iridifolia Rolfe (1897: 167). Type:—ANGOLA. Golungo Alto, s.d., Welwitsch 679 (holotype K!). Bolusiella iridifolia subsp. iridifolia. (Fig. 2B) Epiphytic herb with non-branching stem, 5–9 mm long, internodes 0.8–4.0 mm long. Leaves deeply sulcate on upper surface, 15–38 × 2–4 mm, acinaciform, with bilobate apex. Inflorescences 30–81 mm long, 5–26 flowered. Floral bracts brown, widely triangular, 1.4–3.1 × 1.2–3.4 mm, smaller than flowers, with an acuminate apex, sheathing, and not imbricate in the sterile portion of the inflorescence. Flowers 3.1–4.6 mm long, 1.8–3.1 mm diameter, 1.0–2.5 mm apart from one another. Dorsal sepal triangular, 2–3 × 0.7–1.2 mm. Lateral sepals triangular, 2.1–3.2 × 0.8–1.2 mm, carinate. Petals oval, 1.1–2.5 × 1.0–1.4 mm. Lip triangular, 1.5–2.3 × 0.7–1.0 mm. Spur cylindrical, at right angle to slightly curled under the lip, 1.2–1.9 mm long and 0.4–0.6 mm diameter. Column 0.8–1.0 mm long. Ovary 1.2–2.1 mm long and 0.5–1.1 mm diameter. Chorology & distribution:—Widespread in tropical Africa: Ivory Coast, Ghana, Togo, Cameroon, Central African Republic, Ethiopia, São Tomé & Príncipe (São Tomé), Equatorial Guinea (Rio Muni), Gabon, Republic of Congo, Democratic Republic of Congo, Uganda, Kenya, Rwanda, Burundi, Tanzania, Angola, Zimbabwe and the Comoros (Fig. 8). Habitat & ecology:—Epiphyte in highly humid forest (temporarily to permanently swampy forests) or in more disturbed areas such as coffee or cocoa plantations or on isolated trees. This species can be found at elevations ranging from 100–2,150 m. Flowering peaks in June and in August–February. Conservation status:—IUCN Red List Category: Least Concern [LC]. The extent of occurrence (EOO) of B. iridifolia subsp. iridifolia is estimated to 8,656,610 km2 (far exceeding the upper limit for Vulnerable status), and its area of occupancy (AOO) is about 500 km2 (which falls within the limits for Vulnerable status TAXONOMIC REVISION OF THE GENUS BOLUSIELLA


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under criterion B2). The species is known from 50 subpopulations representing more than 10 locations, the upper limit for Vulnerable status under criterion B2. We are not aware of any current or projected extreme fluctuations in EOO, AOO, number of locations or subpopulations or number of mature individuals. Although its habitat might be threatened, B. iridifolia subsp. iridifolia does not appear as threatened according to the IUCN Red List criteria (IUCN 2001). We expect that the human pressure will decrease its habitat area as well as its AOO but not a significant decrease of its number of subpopulations within the next decade.

FIGURE 8. Distribution of Bolusiella iridifolia subsp. iridifolia.

Etymology:—This species was named for the resemblance of its leaves to those of Iris. Additional specimens examined:—IVORY COAST. Danané à Tiapleu, 18 October 1974, Perez Vera 697 (P, K). GHANA. Ashanti, Kwango mile 35, 1 January 1954, Westwood 79A (K); Begoro to Bosuso, 457 m, 3 December 1967, Bowling GC36623 (K); Leklebi-Dafo, near Togo border, 610 m, 18 April 1967, Bowling GC36607 (K); Ofinso, 1 November 1938, Cox 106 (K); Prasu, 30 August 1955, Westwood 178 (K); Without locality information, 29 December 1952, Lange s.n. (K). CAMEROON. Batouri District: near Dimako, 11 miles into forest of Bertoua - Doumé road, s.d., Sanford 5246 (K); Petit Rocher de Bouamir, 770 m, 21 October 2001, Stévart & Pial 278 (BRLU); Petit rocher de Bouamir, 770 m, 15 October 2002, Stévart & Pial 670 (YA); Central Province: 45 km E of Yaoundé, Mvenn, 700 m, 1964, Atwell 19 (WAG); 22 miles of Yaoundé on Akonolinga road, 19 October 1968, Sanford 5196 (P, YA); Nkolbisson, 8 km W. of Yaoundé, 750 m, 4 November 1963, de Wilde 1143 (WAG); Parc National du Mbam et Djérem, Myéré, 761 m, 02 August 2011, Simo M. et al. (Ombrière de Yaoundé) 2991 (BRLU); Mbouma: 650 m, 01 November 2004, Droissart et al. (Ombrière de Yaoundé) 168 (BRLU); 650 m, 24 October 2001, Stévart & Pial 282 (BRLU); Mindourou: site d'exploitation de la Palisco (AC 5), 760 m, 15 October 2001, Stévart & Pial 264 (BRLU); Ngaoundéré, sur la route de Meiganga (N1), 19 July 2010, Simo M. et al. (Ombrière de Yaoundé) 2236 (BRLU); Ngoko, 1899, Schlechter 12745 (BR, K); Route entre Yokadouma et Mouloundu, 30 km au N de Yokadouma, 480 m, 06 October 2009, Droissart 661 (BRLU); Somalomo village, plantation de café, 650 m, 13 October 2001, Stévart & Pial 257 (BRLU). CENTRAL AFRICAN REPUBLIC. Park Manovo Guonda, St Floris, 640 m, 14 August 1985, Fay 7399 (K). ETHIOPIA. Bebeka, s.d., Fries, Gilbert et al. s.n. (K); Kefa A. Region: At the

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Bebeka Coffee Plantation, south of Mezan Tefari. Near the hot springs 27 km west of the Coffee Plantation H.Q., 950 m, 30 November 1984, Friis, Gilbert & Vollesen 3874 (K); Kefa A. Region: At the Bebeka Coffee Plantation, south of Mezan Tefari. About 5km southwest of the Coffee Plantation H.Q., 1100 m, 4 December 1984, Friis, Gilbert & Vollesen 4007 (K); without locality information, s.d., Gilbert K 6 (K). SÃO TOMÉ ET PRÍNCIPE. São Tomé: Monte Café, 750 m, 4 January 1998, Stévart 345 (BRLU, K); Monte Café, 800 m, 1 July 1998, Stévart 503 (BRLU). EQUATORIAL GUINEA. Rio Muni: Bikurga (inselberg de), près du village de Bikurga. Face SW 220°, 730 m, 18 February 2001, Stévart 810 (BRLU); Ebebiyin to Mikomesong, 33 miles from Ebebiyin, 580 m, 13 February 1969, Sanford 5741 (K, P); near Niefang, Ebebiyin side, 87 miles from Ebebiyin, 396 m, 13 February 1969, Sanford 5765 (K); inselberg de Piedra Nzas, à 9 km d’Aconibe, ou de celui de Afaanam, à 5 km d'Aconibe, 725 m, 27 May 1999, Parmentier & Nguema 382 (BRLU). GABON. Mont Koum: à 1 km du village de Kumassi, à 32 km d'Oyem vers Bitam, 590 m, 25 December 1999, Parmentier & Nguema 1115 (BRLU); à 1 km du village de Kumassi, à 32 km d'Oyem vers Bitam, 655 m, 14 April 2002, Stévart 1318 (BRLU). Irangi, 800 m, 1 October 1989, Babilon 90 (BR); Région du Shaba (Katanga) à environ 21 km au N de "Wahipuije" Sur la route Kolwezi-Luena, 900 m, 31 January 1988, Schaijes 3924 (BR); Entre le Ruwenzori et la Semliki, Parc National Albert (Parc National des Virunga), 850 m, 30 August 1937, Louis 5518 (BR, K); Yangambi, île Esali, 470 m, 3 November 1939, Louis 16266 (BR). UGANDA. Bukoto county, Masaka U4, 2 km NE of Nkoma, 347 m, 13 June 1971, Kare Arnstein Lye, Katende 6227 (K); Bunyoro District: Budongo Forest, December 1942 (fr.) & 14 September 1943 (fl.), Eggeling 5193 (K); Kabarole District: U2, Kibale Forest, Ngogo, 1370 m, 1997, Hafashimana 181 (K); Namanve, near Kampala, 1,371 m, 1934, Synge 1225 (BM); without locality information, 29 September 1962, cult. Kew (K); without locality information, 9 October 1963, cult. Kew (K); without locality information, 14 August 1981, van der Laan 400 (WAG); without locality information, 23 September 1962, no name s.n. (K). KENYA. Kakamega District: Kakamega Forest, Shideya River, on Eastern road from Isecheno to Buyangu, 1,560 m, 14 September 1995, Bytebier 689 (K); Kakamega Forest, Iveko, Buyangu area on the trail to Buyangu hill from the Park Headquarters, 1,570 m, 30 March 2009, Miyawa, Muthoka & Gaya NMK1223 (K); Machakos/Masi Districts: Chyulu-Centre, 26 June 1938, Bally 7854 (K); Uasin Gishu District: Kipkarren R., 1 June 1962, Piers (62) 26 (K). RWANDA. Lac Edouard et Kivu, Nyungwe, s.d., Babilon 43 (BR); Préfecture de Cyangungu, commune de Kirambo, forêt de Uwinka, 2,150 m, 12 May 2000, Ewango 2275 (BR). TANZANIA. Amani, 914 m, 12 August 1941, Moreau 50A (K); Arusha District: Ngurdoto National Park, left bank of the Tululusie River (Arusha Nat. Park.), 1615 m, 7 November 1965, Greenway & Kanuri 12328 (K); Iringa District: Sao Hill, 1 July 1959, Watermeyer 101 (K); Southern face on Longido Mt, 50 miles NW of Kilimanjaro, 29 March 1943, Pullen & Elliot 551 (K); Lushoto/ Tanga Districts: Sigi Segoma, Tang. Terr, 91 m, 16 November 1943, Moreau 736 (K); Marang forest, Mbulu District, 26 June 1942, Moreau 319 (K); Mazumbai, West Usambaras, s.d., Tanner T49 (K); Mlinga Mt. 10 miles E of Amani. East Usambaras, 975 m, 12 August 1941, Moreau 50 (K); Usambara Mts, s.d., Moreau 50A (K); Weru Weru Forest, near Moshi, 1219 m, 19 September 1945, Moreau 843 (K). COMOROS. Without locality information, 1 January 1968, Stewart 904 (K). 6. Bolusiella iridifolia subsp. picea Cribb (1977: 180). (Fig. 2C) Type:—MALAWI/ZAMBIA. Mafinga Hills, February 1970, Williamson 1940 (holotype K!). Heterotypic synonyms: Bolusiella lebeliana Delepierre & Geerinck (1998: 135). Type:—RWANDA, between Butare et Cyangugu, Nyungwe forest, February 1996, Delepierre 36 (holotype BR!). syn. nov.

Description:—Epiphytic herbs with non-branching stems, 3–4 mm long, internodes 1 mm long. Leaves deeply sulcate on upper surface, 9–11 × 2 mm, acinaciform, with bilobate apex. Inflorescences 16–23 mm long, 3–6 flowered. Floral bracts broadly triangular, 1.2–3.0 × 1.8–2.5 mm, acuminate apex, dark brown to black, sheathing, and not imbricate in sterile portions of the inflorescence. Flowers 2.1–2.5 mm × 1.1–1.5 mm, 2–3 mm apart from one another. Dorsal sepal widely triangular, 1.3–1.9 × 0.6–1.7 mm. Lateral sepals triangular, 1.7–2.1 × 0.5–1.9 mm, carinate. Petals ovoid, 1.2–1.7 × 0.7–1.0 mm. Lip broadly triangular, 1.3–



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1.5 × 0.7–1.3 mm. Spur straight, conical, in the same plane as the lip, 0.5–0.8 mm long and 0.5–0.7 mm diameter. Column 0.7–0.8 mm long. Ovary 1.0–1.8 mm long and 0.3–0.7 mm in diameter. Chorology & distribution:—Afromontane Region (Kivu-Ruwenzori, Imatongs-Usambara and UluguruMulanje regional mountain systems): Rwanda, Kenya, Burundi, Tanzania, Zambia, Malawi and Zimbabwe (Fig. 9).

FIGURE 9. Distribution of Bolusiella iridifolia subsp. picea.

Habitat & ecology:—Epiphytic in humid forests, growing in mosses or lichens, or lithophytic near rivers or waterfalls. The subspecies picea is found at higher elevations than the type subspecies, from 1,300–2,400 m. Flowering peaks in September and in January–April. Conservation status:—IUCN Red List Category: Least Concern [LC]. The extent of occurrence (EOO) of B. iridifolia subsp. picea is estimated to 1,275,650 km2 (far exceeding the upper limit for Vulnerable status), and its area of occupancy (AOO) is about 230 km2 (which falls within the limits for Endangered status under criterion B2). The species is known from 23 subpopulations representing more than 10 locations, the upper limit for Vulnerable status under criterion B2. We are not aware of any current or projected extreme fluctuations in EOO, AOO, number of locations or subpopulations or number of mature individuals. Although its habitat is threatened, B. iridifolia subsp. picea does not appear as threatened according to the IUCN Red List criteria (IUCN 2001). We expect that the human pressure will decrease its habitat area as well as its AOO but not a significant decrease of its number of subpopulations within the next decade. Etymology:—The name of this subspecies refers to the black colour of its floral bracts. Discussion:—The choice to recognize this subspecies is justified by the number of morphological characters shared with the nominal subspecies and unique within Bolusiella, such as leaves deeply sulcate on upper surface with a bilobate apex. The only minor distinctive characters are the dark brown to black bracts and the shorter length of the spur (Table 1). The two subspecies also have distinct distribution and are ecologically separated by an elevational difference: B. iridifolia subsp. iridifolia is usually found at lower elevations than B. iridifolia subsp. picea. Unpublished molecular analyses, using matK and ycf1 markers, also show that the two subspecies are clustered in a robust clade distinct from other taxa of the genus.

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3.1–4.6 mm long and 1.8–3.1 mm diameter, 1.0–2.5 mm apart from one another.

2.1–2.5 mm long and 1.1–1.5 mm high, 2–3 mm apart from one another.

Broadly triangular, slightly smaller than flowers, 3.5–7.0 × 2.9–5.0 mm, apex acuminate, brown, sheathing, imbricate in basal half of inflorescence.

Triangular, smaller than flowers, 1.7–3.1 × 1.3–2.2 mm, apex acuminate, brown, sheathing, and not imbricate in sterile portion of inflorescence.

Widely triangular, smaller than the flowers, 1.5–2.3 × 1.4–3.2 mm, with an acuminate apex, brown, sheathing, not imbricate in the sterile portion of inflorescence.

Broadly triangular, 1.4–3.1 × 1.2– 3.4 mm, smaller than flowers, acuminate apex, brown, sheathing, and not imbricate in sterile portion of inflorescence. Broadly triangular, smaller than flowers, 1.2–3.0 × 1.8–2.5 mm, acuminate apex, dark brown to black, sheathing, and not imbricate in sterile portion of inflorescence.

Raceme 31–65 mm long, with a straight (or non-fractiflex) base, 16–24 flowered, grouped at distal half.

Raceme 11–110 mm long, with a straight (or non-fractiflex) base, 2–22 flowered, grouped at distal half.

Raceme 44(18)– 91(211) mm long, with a straight (nonfractiflex) base, 5–23 flowered, grouped at distal half.

Raceme 30–81 mm long, with a straight (non-fractiflex) base, 5–26 flowered, grouped at distal half.

Raceme 16–23 mm long, with a straight (non-fractiflex) base, 3–6 flowered, grouped at distal half.

Not deeply sulcate on upper surface, 15–30 × 5–10 mm, fleshy, ensiform, with rounded apex.

Not deeply sulcate on upper surface, 15–44 × 0.5–7 mm, with acute apex.

Not deeply sulcate on upper surface, 32–65 × 6–8 mm, acinaciform, with rounded apex.

Deeply sulcate on upper surface, 15– 38 × 2–4 mm, acinaciform, with bilobate apex.

Deeply sulcate on upper surface, 9–11 × 2 mm, acinaciform, with bilobate apex.

Bolusiella fractiflexa

Bolusiella maudiae

Bolusiella talbotii

Bolusiella zenkeri

Bolusiella iridifolia subsp. iridifolia

Bolusiella iridifolia subsp. picea

4.3–6.0 mm long and 3.1–5.2 mm diameter, 1–2 mm apart.

3.0–5.1 mm long and 2.0–3.5 mm diameter, 1–3 mm apart from one another.

3.5–4.1 mm long and 1.2–2.1 mm diameter, 1 mm apart from one another.

2.5–3.2 mm long and 1.0–2.0 mm diameter, 1 mm apart.

Triangular, larger than flowers, 4.0–5.0 × 2.4–2.8 mm, acuminate apex, black, sheathing, imbricate in sterile portion of inflorescence.

Raceme 28–36 mm long, with a fractiflex base, 6–9 flowered, grouped distally (10 mm long).

Not deeply sulcate on upper surface, 15–20 × 4–5 mm, ensiform, with pointed apex.

Flowers

Floral bracts

Inflorescence

Leaves

Taxa

TABLE 1. Diagnostic characters (in bold) distinguishing the six recognized species of Bolusiella.

Triangular, 1.7–2.1 × 0.5–1.9 mm.

Triangular, 2.1–3.2 × 0.8–1.2 mm.

Narrowly triangular, 3.3–5.0 × 1.0–1.8 mm.

Broadly triangular, 1.3–1.5 × 0.7–1.3 mm.

Triangular, 1.5–2.3 × 0.7–1.0 mm.

Narrowly triangular, 2.4–3.9 × 1.0–1.2 mm.

Weakly trilobed, 1.6– 3.0 mm × 0.9–1.5 mm.

Triangular, 1.3–2.2 x 1.0–1.6 mm.

Narrowly triangular, 2.8–3.2 × 0.6–1.0 mm, with a basal pouch-like outgrowth.

Triangular, 2–4 × 0.8–1.3 mm.

Broadly triangular, 1.1–1.8 × 1.0–1.2 mm.

Lip

Triangular, 1.9–2.4 × 0.7–1.2 mm, with a basal pouch-like outgrowth.

Lateral sepals

Straight, conical, in the same plane as the lip, 0.5–0.8 mm long and 0.5–0.7 mm diameter.

Cylindrical, at right angle to slightly curled under the lip, 1.2–1.9 mm long and 0.4–0.6 mm diameter.

Cylindrical, with a right angle to partially curled under the lip, 1.8–3.0 mm long and 0.5–1.0 mm diameter.

Cylindrical or conical, at a right angle with the lip, 1.3–2.3 mm long and 0.5–1.0 mm diameter.

Cylindrical, curled under the lip, 1.2–1.6 mm long and 0.4–0.5 mm diameter.

Conical, 1.1 mm long and 0.6 mm diameter, or almost absent in the Cameroon specimens.

Spur

Bolusiella lebeliana has been considered as a synonym of B. iridifolia subsp. picea by Rice (2004) and Govaerts et al. (2012). Close examination and floral dissections of the type specimen of B. lebeliana made it clear to the authors that this taxa represents a synonym of B. iridifolia subsp. picea. Additional specimens examined:—KENYA. Cascade de Nyabihondo: 20 January 1991, Arbonnier 173 (BR); 2,200 m, 3 February 1992, Arbonnier 309 (BR). Machakos/Masai Districts: Chyulu Hills, 1,585 m, 6 May 1938, Bally 8402 (K). Ngong Hills: 1,371 m, 14 April 1952, Archer 52 (K); 2,332 m, 13 February 1985, Khayota 166 (K). Taita Taveta: Forêt de Mbololo, 1600 m, 3 June 1998, Bytebier 1188 (BR). TANZANIA. Dedza District: Chiwao Hill, Chongoni Forest Reserve, 8 September 1967, Salubeni 824 (K). Mbeya District: Umalila, Idunda, T7, 2,133 m, 31 March 1975, Leedal 2627 (K). Kilimanjaro District: Kilimanjaro, South Pare Mountains, 1700–1800 m, 23 September 1986, van der Laan 1082 (WAG); Livingstone Forest Reserve Below ridge, W. of Lufirio river, T7, 1,890 m, 22 June 1976, Cribb & Grey-Wilson 10630 (K). Lushoto District: Mkusu Valley between Mkusi and Kifungilo, West Usambaras, 1,600 m, 23 April 1953, Drummond, Hemsley 2206 (K); Magamba Forest Reserve: near Lushoto, W. Usambaras, T3, 1,768 m, 10 January 1976, Cribb & Grey-Wilson 10135 (K); Marangu, on track to road leading from Lake at Marangu to W., Ukagurus, T6, 1676 m, 1 February 1976, Cribb & Grey-Wilson 10513 (K); Mazumbai Forest Reserve, West Usambara Mts T3, 1,300 m, 13 September 1975, Tanner 49 (K). Njombe District: Kipengere Mts. Nyarere River, 2,400 m, 10 January 1957, Richards 7644A (K); 2km S of Njombe in the southern highlands, 26 July 1986, van Setten 930 (WAG). Songea District: Matengo Hills, Lupembe Hill, 1,860 m, 3 March 1956, Milne-Redhead, Taylo 8964 (K); West Usambara Mts, Mazumbai Forest, just below Philippia zone, T3, 1,829 m, 7 January 1976, Cribb & Grey-Wilson 10050 (K). Without data, Cuthbert s.n. (K); without data, Keeley s.n. (K). ZAMBIA. Lake Kanlime: s.d., Williamson 860 (K). Nyika Plateau: Kasoma forest, 2000 m, 24 February 1982, Dowsett-Lemaire 367 (K); s.d., Williamson 372 (K); February 1968, Williamson 384 (K); August 1968, Williamson 1056 (K). MALAWI. Chombe Plateau: 1,829 m, 7 November 1979, Morris 342 (K). Central Region: Dedza Mt, 2,000 m, 23 February 1985, la Croix 669 (K); Mlanje Mt, 1981 m, 22 August 1964, Morris 48 (K); Mlanje Mt, 1,981 m, s.d., Morris 204 (K). Kericho District: Rift Valley, Kericho Tea-Hotel, downwards through garden and teafields, along the banks of Kipkariet River, 2,100 m, 22 August 1986, van der Laan 1234 (WAG). Southern Region: Zomba Mt, 10 March 1985, la Croix 679 (K). ZIMBABWE. Chimanimani Mts: on Hanoni River below nesthouse, 1 April 1959, Holmes 158 (K). Umtali District: Numba Mts, 1,524 m, 26 June 1955, Chase 5611 (BM); Vumba Clouds Downs, 1,707 m, s.d., Head 194 (BM). Vumba District: 1,524 m, March 1949, Wild 22737 (K). Without data, Chase 6326 (K).

Acknowledgements We express our sincere gratitude to Valéry Malécot, who helped us to resolve some issues surrounding Bolusiella maudiae. We are grateful to curators and staff of BM, BR, BRLU, K, MA, P, WAG and YA for making their collections available and for the facilities in their institutions offered to the authors. The American Orchid Society is gratefully acknowledged for supporting Ph.D. research of M. Simo-Droissart in Cameroon, and orchid inventories in Gabon. The “Sud Expert Plantes” project (project #375) under French Ministry of Foreign Affairs provided financial support for our fieldwork in Cameroon. Fieldwork, laboratory activities and herbarium visits were supported by the U.S. National Science Foundation (1051547, T. Stévart as PI, G. M. Plunkett as Co-PI.). Finally, we would like to thank Phillip J. Cribb, Johan Hermans and Mark W. Chase for their constructive comments on an earlier version of this paper.

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