Bolusiella iridifolia subsp. iridifolia

Verlynde, Simon, Dubuisson, Jean-Yves, Stévart, Tariq, Droissart, Murielle Simo-, Geerinck, Daniel, Sonké, Bonaventure, Cawoy, Valérie, Descourvières, Pascal & Droissart, Vincent, 2013, Taxonomic revision of the genus Bolusiella (Orchidaceae, Angraecinae) with a new species from Cameroon, Burundi and Rwanda, Phytotaxa 114 (1), pp. 1-22 : 15-20

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 km 2 (far exceeding the upper limit for Vulnerable status), and its area of occupancy (AOO) is about 500 km 2 (which falls within the limits for Vulnerable status 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.

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 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– 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 Uluguru- Mulanje regional mountain systems): Rwanda, Kenya, Burundi, Tanzania, Zambia, Malawi and Zimbabwe ( Fig. 9 ).

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 km 2 (far exceeding the upper limit for Vulnerable status), and its area of occupancy (AOO) is about 230 km 2 (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 mat K and ycf 1 markers, also show that the two subspecies are clustered in a robust clade distinct from other taxa of the genus.

Taxa Leaves Inflorescence Floral bracts Flowers Lateral sepals Lip Spur

Conical, 1.1 mm long

Raceme 28 – 36 mm Triangular, larger than flowers, Triangular, 1.9 – 2.4

Not deeply sulcate on 2.5 – 3.2 mm long and 0.6 mm

long, with a fractiflex 4.0 – 5.0 × 2.4 – 2.8 mm, acuminate × 0.7 – 1.2 mm,

Bolusiella upper surface, 15 – 20 and 1.0 – 2.0 mm Broadly triangular, diameter, or almost base, 6 – 9 flowered, apex, black, sheathing, imbricate with a basal

fractiflexa × 4 – 5 mm, ensiform, diameter, 1 mm 1.1 – 1.8 × 1.0 – 1.2 mm. absent in the grouped distally (10 in sterile portion of pouch-like

with pointed apex. apart. Cameroon

mm long). inflorescence. outgrowth.

specimens.

Narrowly

Not deeply sulcate on Raceme 31 – 65 mm Broadly triangular, slightly 3.5 – 4.1 mm long

triangular, 2.8 – 3.2 Cylindrical, curled

upper surface, 15 – 30 long, with a straight smaller than flowers, 3.5 – 7.0 × and 1.2 – 2.1 mm

Bolusiella × 0.6 – 1.0 mm, Triangular, 1.3 – 2.2 x under the lip, 1.2 – 1.6 × 5 – 10 mm, fleshy, (or non-fractiflex) 2.9 – 5.0 mm, apex acuminate, diameter, 1 mm

maudiae with a basal 1.0 – 1.6 mm. mm long and 0.4 – 0.5 ensiform, with base, 16 – 24 flowered, brown, sheathing, imbricate in apart from one

pouch-like mm diameter.

rounded apex. grouped at distal half. basal half of inflorescence. another.

outgrowth.

Raceme 11 – 110 mm Triangular, smaller than flowers, 3.0 – 5.1 mm long Cylindrical or conical, Not deeply sulcate on long, with a straight 1.7 – 3.1 × 1.3 – 2.2 mm, apex and 2.0 – 3.5 mm at a right angle with Bolusiella upper surface, 15 – 44 Triangular, 2 – 4 × Weakly trilobed, 1.6 – (or non-fractiflex) acuminate, brown, sheathing, and diameter, 1 – 3 mm the lip, 1.3 – 2.3 mm talbotii × 0.5 – 7 mm, with 0.8 – 1.3 mm. 3.0 mm × 0.9 – 1.5 mm. base, 2 – 22 flowered, not imbricate in sterile portion of apart from one long and 0.5 – 1.0 mm acute apex. grouped at distal half. inflorescence. another. diameter.

Raceme 44(18) – Widely triangular, smaller than

Not deeply sulcate on Cylindrical, with a

91(211) mm long, with the flowers, 1.5 – 2.3 × 1.4 – 3.2 4.3 – 6.0 mm long

upper surface, 32 – 65 Narrowly right angle to partially

Bolusiella a straight (non- mm, with an acuminate apex, and 3.1 – 5.2 mm Narrowly triangular,

× 6 – 8 mm, triangular, 3.3 – 5.0 curled under the lip,

zenkeri fractiflex) base, 5 – 23 brown, sheathing, not imbricate in diameter, 1 – 2 mm 2.4 – 3.9 × 1.0 – 1.2 mm.

acinaciform, with × 1.0 – 1.8 mm. 1.8 – 3.0 mm long and

flowered, grouped at the sterile portion of apart.

rounded apex. 0.5 – 1.0 mm diameter.

distal half. inflorescence.

Deeply sulcate on Raceme 30 – 81 mm Broadly triangular, 1.4 – 3.1 × 1.2 – 3.1 – 4.6 mm long Cylindrical, at right Bolusiella

upper surface, 15 – long, with a straight 3.4 mm, smaller than flowers, and 1.8 – 3.1 mm angle to slightly curled iridifolia Triangular , 2.1 – 3.2 Triangular, 1.5 – 2.3 ×

38 × 2 – 4 mm, (non-fractiflex) base, acuminate apex, brown, diameter, 1.0 – 2.5 under the lip, 1.2 – 1.9 subsp. × 0.8 – 1.2 mm. 0.7 – 1.0 mm.

acinaciform, with 5 – 26 flowered, sheathing, and not imbricate in mm apart from one mm long and 0.4 – 0.6 iridifolia

bilobate apex. grouped at distal half. sterile portion of inflorescence. another. mm diameter.

Broadly triangular, smaller than

D eeply sulcate on Raceme 16 – 23 mm 2.1–2.5 mm long Straight, conical, in

flowers, 1.2 – 3.0 × 1.8 – 2.5 mm,

Bolusiella upper surface, 9 – 11 long, with a straight and 1.1 – 1.5 mm the same plane as the acuminate apex, dark brown to Triangular, 1.7 – 2.1 Broadly triangular,

iridifolia × 2 mm, (non-fractiflex) base, high, 2 – 3 mm lip, 0.5 – 0.8 mm long black, sheathing, and not × 0.5 – 1.9 mm. 1.3 – 1.5 × 0.7 – 1.3 mm.

subsp. picea acinaciform, with 3 – 6 flowered, grouped apart from one and 0.5 – 0.7 mm imbricate in sterile portion of

bilobate apex. at distal half. another. diameter.

inflorescence.

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).

Figures

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.

FIGURE 8. Distribution of Bolusiella iridifolia subsp. iridifolia.

FIGURE 9. Distribution of Bolusiella iridifolia subsp. picea.