Benna alternifolia (Melastomataceae: Sonerileae), a new herbaceous genus and species from Guinea, West Africa van der Burgt, Xander M. Haba, Pepe M. Magassouba, Sékou Veranso-Libalah, Marie Claire Willdenowia 2022 2022-02-16 52 1 25 37 9CD8N Burgt & Ver.-Lib. Burgt & Ver. - Lib. 2022 [794,1200,841,865] Magnoliopsida Melastomataceae Benna Plantae Myrtales 7 31 Tracheophyta species alternifolia sp. nov.    Holotype: Guinea, Forécariah Prefecture, slopes of Benna Plateau, 3 kmW of Gombokori village, 09°44'06"N, 12°49'00"W,  770 m, flower buds,  11 Feb 2019,  Burgt, Haba, Konomou& Xanthos 2274( HNG;  isotypes: K001381567,  MO,  P,  WAG).   Description— Herbs, perennial, evergreen, half-spherical in shape, up to 1.2 min diam., with up to 60 leaves per plant. Rootswoody; thin roots up to 0.5 m× 4 mm, radiating on rock surface and attaching plant to rock; thick roots up to 10 m× 2 cm, entering rock fissures in search of permanent water seepage, bark deeply fissured, up to 5 mmthick. Stemssomewhat woody, branched from base, pendent, circular in cross-section, up to 28 cm× 6–12 mm, reddish green, densely to sparsely hairy with red hairs up to 4 mmlong, puberulent with red glandular hairs up to 0.1 mmlong; internodes up to 3 cmlong, leaf petiole pointing in same direction as internode just below it. Leavesalternate; petiole succulent, 15–45 cm× up to 6 mm, reddish green to bright red, densely hairy to glabrescent with red hairs up to 7 mmlong, puberulent with red glandular hairs up to 0.1 mmlong; leaf blade round to ovate, 12–31 × 10–28 cm, shrinking a little during drying, lower surface dull glaucous light green, upper surface glossy green, both surfaces puberulent with red glandular hairs up to 0.1 mmlong, veins below with red hairs up to 5 mmlong; leaf base deeply cordate, left or right half of leaf base often overlapping other half; leaf margin dentate, teeth with a single red hair up to 4 mmlong, distance between teeth 4–24 mm; leaf apex rounded, mucronate; leaf venation acrodromous, 11–15 veins all starting from top of petiole, central vein straight, other veins curved, otherwise similar in appearance to primary vein, secondary and tertiary venation scalariform, venation on lower surface prominent, light red, on upper surface flattened, light red. Inflorescencecymose, paniculate, axillary, up to 4 cmlong when in bud, with up to c. 70 flower buds, branching alternate; peduncle up to 1 × 3 mm, internodes 0.5–15 mmlong; bracts and bracteole persistent, lanceolate, c. 1 mmlong; peduncle and rachides red, puberulent with red glandular hairs up to 0.1 mmlong. Flowers: flower buds 4-merous, epigynous; pedicel up to 24 mmlong, red, puberulent with red glandular hairs up to 0.1 mmlong; hypanthium cupuliform, c. 4 × 4 mm, light reddish green, puberulent with red glandular hairs up to 0.1 mmlong, part of hypanthium free from ovary c. 2 mmlong; calyx lobes 4, free, triangular, c. 1.5 × 2.5 mm, light green with pink apex, puberulent with red glandular hairs up to 0.2 mmlong, margin ciliate, apex mucronate, mucro c. 0.3 mmlong; petals 4, free, convolute, overlapping counterclockwise when viewed from above, alternate to sepals, round to ovate, in bud c. 6 × 5 mm, light pink, both surfaces and margin glabrous, acuminate with acumen c. 1 mmlong, claw c. 0.5 × 1 mm; stamens 8, fertile, actinomorphic, dimorphic, glabrous; 4 antisepalous stamens: filaments c. 2 mmlong, connective with a 3-lobed appendage, c. 2 × 2 mm, anther c. 3 × 1 mm, with 2 loculi; 4 antipetalous stamens: filaments c. 1 mmlong, connective with a 3-lobed appendage, c. 1 × 1 mm, anther c. 2 × 1 mm, with 2 loculi; ovary inferior, in bud c. 2 mmlong, 4-locular, loculi opposite sepals, each locule with c. 100 ovules; style straight, in bud c. 4 mmlong, glabrous, stigma punctiform. Infructescenceup to 9 cmlong, with up to 70 fruits, peduncle up to 1 × 4 mm, internodes 0.5–18 mmlong, lower internodes up to 2 mmlong, middle internodes up to 18 mmlong, upper internodes up to 5 mmlong; bracts and bracteole caducous; peduncle and rachides red, puberulent with red glandular hairs up to 0.1 mmlong. Fruita capsule, urceolate, 4–5 × 3–4 mm, glabrescent, calyx persistent, fruit apically dehiscent, crown lobes not seen; fruit pedicel 20–60 mmlong. Seedsup to 400 per fruit, obovoid or nearly so, 0.4–0.5 × 0.3–0.4 mm, glossy, testa smooth, yellow to light brown.   Phenology — Benna alternifoliaflowers in February– March and fruits a few months later. Old, decaying fruits containing ripe seeds may remain on the plants until November, because the plants are little disturbed by wind and rain in their sheltered habitat. Distribution — Benna alternifoliais endemic to Guinea( Fig. 5) and occurs in Forécariah Prefecture near border with Kindia Prefecture, in canyons of the Benna Plateau near villages Dalonia and Gombokori.  Habitat and ecology — Benna alternifoliaoccurs on vertical sandstone rock, in deep shade in canyons 10–100 mdeep ( Fig. 3), and on vertical sandstone rock in deep shade of trees, at 300–800 maltitude. Plants occur only under overhanging rocks ( Fig 3B), out of reach of falling rain drops, and only on vertical rock where water is seeping all year round, within reach of the several-meter-long roots. In this habitat, the perennial, evergreen, herbaceous plants, which do not have a rootstock, can continue to grow during the six-month dry season.   Benna alternifoliais often found together with Cincinnobotrys felicis( A. Chev.) Jacq.-Fél. (  Melastomataceae),  Impatiens bennae(  Balsaminaceae) and  Mesanthemum bennae(  Eriocaulaceae). On the same vertical rocks, but higher up and in sunny, seasonally dry habitat, two plant species endemic to Guineaoccur abundantly:  Cailliella praerupticola(  Melastomataceae) and Pitcairnia feliciana(  Bromeliaceae), the only member of the family that is native outside America.   Conservation status — Benna alternifoliais currently known only in the Benna Plateauin Forécariah Prefecture. The collectors searched for the species elsewhere in the region, without success. The habitat of the species was found to occur widespread in an expanse of sandstone plateaus occupying much of Coyah, Dubreka, Forécariah and Kindia Prefectures in Guinea( Fig. 5), but the species was not found. The Benna Plateauis currently unprotected and was not proposed as a TIPA(Tropical Important Plant Area) by Couch & al. (2019), because the exact location of the Benna Plateauwas unknown to the authors at the time of that publication. The Benna Plateauis rich in rare plant species and is proposed here to become a TIPA. The extent of occurrence of  Benna alternifoliawas 3.4 km 2and the area of occupancy was 12 km 2, both calculated with Geocat (2021). The extent of occurrence is changed to 12 km 2, because it should not be smaller than the area of occupancy ( IUCN 2019). The number of locations is two. These values may become larger if the species is found in other canyons. The species currently does not seem exposed to any threats. The habitat where the species occurs is free of fire. There are no known mineral deposits in the vicinity. Plants were only found in remote canyons where they will not be threatened by rock quarrying. In absence of any threats to the species, IUCN (2012)categories A, Band Care not eligible. About 680 mature individuals of  B. alternifoliawere found. There exist probably more than 1000 mature individuals, because some canyons in and near the Benna Plateauare yet to be explored. The species may be close to qualifying for the IUCN (2012)Red List category Vulnerable under criterion D1, which has a threshold of 1000 mature individuals, and  B. alternifoliais therefore assessed here in the IUCNcategory Near Threatened.   Seed conservation— Seeds were collected from 12 plants of Burgt & Haba 2333and are stored in the seed bank of the National Herbarium of Guineain Conakry (c. 250 seeds) and at Kew’s Millennium Seed Bank(also c. 250 seeds).   Etymology— The genus is named for the Benna Plateauor Benna Gadyahin the Susu language. The Benna Plateauholds the only known locations for the species. The specific epithet refers to the alternate leaf arrangement.   Vernacular name— In the Susu language, the name of  Benna alternifoliais Labalaba Khamè or Labalaba Hamey, which means “male soft leaf”. The name Labalaba is given to  Piper umbellatum L. ( Burkill 1997, vol 4: p. 441), a herb with leaves similar in size and appearance. On the Benna Plateau,  Piper umbellatumis named Labalaba Guinè, which means “female soft leaf”.   Additional specimens examined— GUINEA: Forécariah Prefecture, canyon at base of Benna Plateau, 3.5 km Nof Dalonia village, 09°41'53"N, 12°50'03"W, 330 m, fruits, 26 Oct 2019, Burgt, Haba & Holt 2323( B, HNG, K, MO, P, WAG); slopes of Benna Plateau, 3.5 km Wof Gombokori village, 09°44'07"N, 12°49'26"W, 810 m, fruits, 1 Nov 2019, Burgt & Haba 2333( HNG, K). 5225408302 2019-02-11 HNG Burgt & Haba & Konomou & Xanthos Guinea-Bissau 770 9.735001 slopes of Benna Plateau, 3 km W of Gombokori village 21 -12.816667 Forecariah Prefecture 7 31 1 holotype 5225408304 2019-02-11 K Burgt & Haba & Konomou & Xanthos Guinea-Bissau 770 9.735001 slopes of Benna Plateau, 3 km W of Gombokori village 21 -12.816667 Forecariah Prefecture 7 31 K001381567 1 isotype 5225408303 [946,996,1034,1057] 2019-02-11 MO Burgt & Haba & Konomou & Xanthos Guinea-Bissau 770 9.735001 slopes of Benna Plateau, 3 km W of Gombokori village 21 -12.816667 Forecariah Prefecture 7 31 1 isotype 5225408301 [1003,1021,1034,1057] 2019-02-11 P Burgt & Haba & Konomou & Xanthos Guinea-Bissau 770 9.735001 slopes of Benna Plateau, 3 km W of Gombokori village 21 -12.816667 Forecariah Prefecture 7 31 1 isotype 5225408305 [1027,1099,1034,1057] 2019-02-11 WAG Burgt & Haba & Konomou & Xanthos Guinea-Bissau 770 9.735001 slopes of Benna Plateau, 3 km W of Gombokori village 21 -12.816667 Forecariah Prefecture 7 31 1 isotype