Two new species of Oxyanthus DC. (Rubiaceae) from Central Africa Sonké, Bonaventure Lachenaud, Olivier Candollea 2016 2016-06-17 71 2 173 180 8WZJR Sonke & O. Lachenaud Sonke & O. Lachenaud 2016 [842,1324,794,818] Magnoliopsida Rubiaceae Oxyanthus Plantae Gentianales 1 174 Tracheophyta species doucetii sp. nov.     Typus: CAMEROON. South Region:  16 kmon the road from Ebolowa to Minkok, 2°58’N 11°17’E,  28.IV.1975, fl.,  De Wilde8207(holo-: BR!; iso-: P[ P04006788]!, WAG[ WAG.1228575, WAG.1228576, WAG.1228577]!, YA!).    Oxyanthus doucetii Sonké & O. Lachenaudclosely resembles O. unilocularis Hiernin the large and broad asymmetrical leaves with sparsely pilose lower surface, and the manyflowered inflorescences with long corollas. The species differs from O. unilocularisin the minute calyx teeth (< 0.3 mmlong), the stems with glabrous internodes, the stipules glabrous except sometimes on their margin, the flower buds with a shorter head 8.5-11 mmlong, and the corolla lobes not or hardly acute at apex; by contrast, O. unilocularishas well-developed subulate calyx teeth 1.5-10(-14) mm long, densely puberulous stems and stipules, the head of the flower buds 12-25 mmlong, and the corolla lobes sharply acute at apex.  Shrubor small tree, 2-10 mtall, with horizontal branches; stems hollow, 7-14 mmthick, glabrous or with short sparse hairs at the nodes only. Stipules23-48 X 16-25 mm, broadly mitriform with ± acute apex, glabrous or sparsely ciliate, persistent (except at flowering nodes, where often caducous). Leaveswith petiole 0.5-1.5 cm, glabrous or with short sparse hairs, and leaf blades 34-60 X 18-30 cm, very broadly elliptic, strongly asymmetrical at base with proximal side rounded to cordate and distal side acute to obtuse inserted 5-12 mmhigher, acute or shortly acuminate at apex, glabrous above, sparsely pilose below with ± scabrid erect hairs 0.7-1 mmlong; lateral nerves 12-13 pairs, strongly ascending (except the lower ones) and forming loops well away from the margin; tertiary veins laxly reticulate; domatia absent. Inflorescencespseudo-axillary, one per branch and per season, corymbiform, glabrous, with several hundred flowers but usually producing   Fig. 1. –  Oxyanthus doucetiiSonké & O. Lachenaud. A.Inflorescence; B.Apex of twig with one leaf and the base of the opposite leaf (pubescence shown on a portion of the leaf); C.Apex of twig with stipules; D.Calyx; E.Detail of the apex of a flower bud; F.Detail of opened flower showing the lobes and upper part of tube; G.Fruit. [ A, D-F: J.J. de Wilde 8207, BR; B, G: Sonké 124, BR; C: Sonké et al. 2758, BR] [Drawing: A. Fernandez] only few fruits; peduncle 0.6-1.5 cmlong, rhachis 5-10.5 cmlong, lateral branches 1.5-4 cmlong. Bractsminutely triangular, <1(-1.5) mm, glabrous. Flowers5-merous; pedicels 2-8 mmlong, glabrous. Ovary 1.5-2 mmlong, glabrous. Calyxwith tube 0.7-1 mmlong and minute, acutely triangular teeth 0.2-0.3 mmlong, entirely glabrous. Corollatube pale green, very narrowly cylindrical, 12.2-13.7 cmlong X c. 0.2 cmwide, glabrous; corolla lobes white, lanceolate, obtuse or only faintly acute at apex, 1.2-1.7 cmlong X 0.25-0.3 cmwide, glabrous outside, shortly papillose inside. Anthersexserted, ± patent, inserted at the corolla throat, linear, 3-5 X 0.5 mmincluding a sterile apical appendage 0.5-1 mmlong, glabrous. Styleexserted, exceeding corolla throat by 1.5-2 cm, glabrous, with slightly swollen elongated stigma. Fruitsgreen, smooth, ovoid to globose, 1.3-2.7 X 1.4-2 cmwhen dry, glabrous, with pedicel not markedly accrescent and calyx persistent. Seedsnumerous, irregularly polygonal and compressed, c. 9 X 5 mm, the surface folded into numerous closely parallel ridges.   Etymology.– The species name honours Prof. Jean-Louis Doucet, specialist in tropical forestry (Université de Liège, Gembloux Agro-Bio Tech, Belgium), to whom the first author is particularly indebted for his constant support.   Distribution and ecology. –  Oxyanthus doucetiiis endemic to Cameroonin the Lower GuineaDomain ( Fig. 2), and is found mostly in the Central Region around Yaoundé, more rarely in the southwest (Mt. Cameroon) and South Regions (around Bipindi and Ebolowa). The species occurs in primary and secondary forests between 480 and  760 m.  Phenology. – Flower buds in October-November, mature flowers in April; fruits in March, June-July (immature) and from September to December.   Conservation status. – The EOO is estimated as c. 35,435 km 2and AOO as 44 km 2. The species is known from nine locations. None of these locations are protected, and deforestation for agriculture (and also for urban extension in the periphery of Yaoundé) represents a clear threat to the species. A decline in AOO, extent and quality of habitat, number of locations and number of individuals is therefore expected, and  O. doucetiiis assigned a preliminary conservation status of “Vulnerable” [VU B2ab(i,ii,iii,iv)].   Notes.– As mentioned above,  O. doucetiihas previously been confused with the morphologically similar, and presumably closely related,  O. unilocularis. It differs from the latter in having minute calyx teeth (< 0.3 mmlong), the stems with glabrous internodes, the stipules glabrous except sometimes on their margin, the flower buds with a shorter head 8.5- 11 mmlong, and the corolla lobes not or hardly acute at apex (compare Fig. 1and 3). Additionally,  O. doucetiitends to have larger and broader stipules (23-48 X 16-25 mm) than  O. unilocularis(7-35 X 4-22 mm), but this character shows significant overlap between the two species. The stipules of  O. doucetiiare the largest in the genus. Two sterile collections from Mt Kolodom near Yaoundé, Sonké 120 & 121(BR), are intermediate between  O. doucetiiand  O. unilocularisin vegetative characters. The internodes are very sparsely pubescent, often only towards the apex, and the stipules are pubescent only at the base and margins. In the absence of fertile material, these collections cannot be referred with certainty to either species; they may represent hybrids, since both species are found in the region.     Paratypi. –  CAMEROON.  Central Region: Yaoundé, NE, 1939, fl. buds,  Jacques-Félix4799( BR);  Nkolakié, 3°57’N 11°21’E,  VII.2010, fr. imm.,  Kayo1( BR);  ibid. loc.,  4.V.2003, fl. (fallen),  Nguembou& Djuikouo665( BRLU);  ibid. loc.,  8.VI.2003, fl.,  Nguembou& Djuikouo796( BR, BRLU);  Mont Kala, 3°53’N 11°30’E,  5.V.2004, fl. buds,  Nguembouet al. 1202( BR, BRLU);  Mont Ngoa Ekele[ 3°51’N 11°24’E],  4.XII.1986, fr.,  Sonké43( BR, YA);  Mt Akondoué[ 3°50’N 11°29’E],  23.IV.1987, fl. buds,  Sonké95( BR, K, YA);  ibid. loc.,  29.IX.1987, fr.,  Sonké116( BR, WAG);  ibid.loc.,  31.X.1987, fl. buds & fr.,  Sonké117( BR);  Mt Kala,  14.XI.1987, fr.,  Sonké123( BR, YA);  ibid. loc.,same date,  Sonké124( BR, YA);  Mt Kolodom, [ 3°51’N 11°22’E],  23.IV.1988, fl.,  Sonké141( BR, YA);  Nkolfep, Massif du Mbaminkom, 3°58’N 11°23’E,  3.III.2002, fr.,  Sonké, Nguembou& Djuikouo2758( BR, BRLU);  Ndjamtchourou (Ngoro), 4°57’N 11°20’E,  20.VII.2009, fr. imm.,  Sonké& Simo5297( BR).   South Region: Bipindi, 3°5’N 10°24’E,  26.XI.2004, fl. buds & fr.,  Sonké& Nguembou3598( BR).   Southwest Region: env. du village Efolofo, pentes septentrionales du Mt Cameroun, 4°21’N 9°7’E,  1.VI.1976, fr. imm.,  Satabié300( BR, P, YA). 3417100319 1975-04-28 P, WAG De Wilde Cameroon 2.9666667 South Region 1307 11.283334 Ebolowa 1 174 P04006788, WAG.1228575, WAG.1228576, WAG.1228577 1 South Region type 3417100305 1986-12-04 2010-07 1986-12-04 BR Jacques-Felix Cameroon Jacques-Felix 4.95 Central Region 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100308 2010-07 2010-07 1986-12-04 BR Kayo Cameroon Jacques-Felix 4.95 Nkolakie 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100317 [878,1460,1273,1293] 2003-05-04 2010-07 1986-12-04 BRLU Nguembou & Djuikouo Cameroon Jacques-Felix 4.95 Mt Akondoue 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100322 [804,1352,1302,1321] 2003-06-08 2010-07 1986-12-04 BR, BRLU Nguembou & Djuikouo Cameroon Jacques-Felix 4.95 Mt Akondoue 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100320 2004-05-05 2010-07 1986-12-04 BR, BRLU Nguembou Cameroon Jacques-Felix 4.95 Mont Kala 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100306 1986-12-04 2010-07 1986-12-04 BR, YA Sonke Cameroon Jacques-Felix 4.95 Mont Ngoa Ekele 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100316 1987-04-23 2010-07 1986-12-04 BR, K, YA Sonke Cameroon Jacques-Felix 4.95 Mt Akondoue 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100314 1987-09-29 2010-07 1986-12-04 BR, WAG Sonke Cameroon Jacques-Felix 4.95 Mt Akondoue 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100311 1987-10-31 2010-07 1986-12-04 BR Sonke Cameroon Jacques-Felix 4.95 Mt Akondoue 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100313 [897,1286,1442,1462] 1987-11-14 2010-07 1986-12-04 BR, YA Sonke Cameroon Jacques-Felix 4.95 Mt Kala 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100303 1986-12-04 2010-07 1986-12-04 BR, YA Sonke Cameroon Jacques-Felix 4.95 Mt Akondoue 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100307 1988-04-23 2010-07 1986-12-04 BR, YA Sonke Cameroon Jacques-Felix 4.95 Mt Kolodom 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100312 2002-03-03 2010-07 1986-12-04 BR, BRLU Sonke & Nguembou & Djuikouo Cameroon Jacques-Felix 4.95 Nkolfep 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100304 2009-07-20 2010-07 1986-12-04 BR Sonke & Simo Cameroon Jacques-Felix 4.95 Ndjamtchourou (Ngoro) 1306 11.333333 Nkolakie 3 176 1 Central Region paratype 3417100309 2004-11-26 BR Sonke & Nguembou Cameroon 3.0833333 South Region 1307 10.4 3 176 1 South paratype 3417100310 1976-06-01 BR, P, YA Satabie Cameroon 4.35 env. du village Efolofo 1306 9.116667 Efolofo 3 176 1 Southwest Region paratype