Ancistrocladus korupensis (Ancistrocladaceae): A New Species of Liana from Cameroon

Abstract

Ancistrocladus korupensis, a species here described from the Southwest Province of Cameroon and adjacent Nigeria, is distinguished within the genus by sessile leaves, short petals, and longwinged fruits. The new species was investigated after michellamine B, a unique naphthyl isoquinoline alkaloid isolated from a sterile Ancistrocladus leaf collection, showed in vitro activity against HIV-1 and HIV-2. Subsequent collections showed that the liana was undescribed and apparently narrowly endemic to the Korup area. Ancistrocladus Wallich (nom. conserv.) is a genus of 19 known species: 9 in tropical Asia (Dyer, 1874; Gagnepain, 1909; Craib, 1925; Steenis, 1948; Ramamoorthy, 1976; Harriman, 1987) and 10 in tropical Africa (Pellegrin, 1951; Hutchinson & Dalziel, 1954; Leonard, 1982, 1986). The resemblance of the winged fruits of Ancistrocladus spp. to those of the Dipterocarpaceae Blume has led some authors (e.g., Oliver, 1868; Dyer, 1874) to include the genus in the latter family. However, Gilg (1925) noted that the resemblance is strictly superficial and considered the Ancistrocladaceae Walpers (nom. conserv.) to be a monogeneric family in the Parietales. The results of anatomical (Metcalfe, 1952; Schmid, 1964; Gottwald & Parameswaran, 1968) and palynological (Erdtman, 1958) investigations support an affinity between Ancistrocladaceae and the endemic African family Dioncophyllaceae Airy Shaw; Cronquist (1981, 1988) treated the two as closely allied families of the Violales. The Ancistrocladaceae are distinguished within the Violales (Cronquist, 1981) and among all of the dicotyledonous families of central Africa (Robyns, 1958) by the following diagnosis: plants lianas, not succulent, climbing by hooked apices of sympodial branches; leaves alternate (but often crowded in rosettes on flowering shoots), simple, entire, not sheathing at base, the blades symmetric; stipules present, very small and caducous; flowers in raNOVON 3: 494-498. 1993. cemes, spikes, or dichotomously branched panicles; sepals 5, accrescent and winglike in fruit; petals distinct or slightly connate at base; extrastaminal corona lacking; stamens 5 or 10-15, erect in bud, the filaments slightly connate at base; ovary halfinferior, unilocular; ovule solitary, basilateral; fruit dry, indehiscent; endosperm present, ruminate. Ancistrocladus can sometimes be confused with the unrelated genus Hugonia L. (Hugoniaceae or Linaceae), but species of the latter genus can be vegetatively distinguished by the usually pale stems, leaves usually toothed, less crowded, and with numerous more prominent secondary veins, and hooks borne on normal branches. Of the ten species of Ancistrocladus previously described from tropical Africa, six occur in the evergreen forests near the Atlantic coast from Gabon to Sierra Leone (Pellegrin, 1951; Hutchinson & Dalziel, 1954), three are apparently restricted to central and northern Zaire (Leonard, 1982), and one is endemic to the Buda Forest of coastal Kenya (Leonard, 1986). The new species herein described is apparently endemic to the immediate vicinity of the Korup National Park in the Southwest Province of Cameroon, including the adjacent part of Cross River State of southeastern Nigeria. Ancistrocladus korupensis D. W. Thomas & Gereau, sp. nov. TYPE: Cameroon. Southwest Prov.: Ndian Division, 0.6 km E of confluence of Mededibe (Moliba) and Ndian (Mana) Rivers, 90 m, 5?02'N, 8?53'E, 4 Mar. 1993, Gereau, Thomas, F. Namata & E. Jato 5180 [infructescences and fallen fruits] (holotype, MO; isotypes, K, P, SCA, YA). Figure 1. Plantae omnino glabrae. Caules adulti parce ramosi; ramis principalibus elongatis, rectis subcurvatisve; ramis lateralibus extra-axillaribus, uncos gerentibus. Folia adulta sessilia, ex formis duabus constantia: folia ramorum principalium remote disposita, ex ellipticis oblonga, basi cuneata, apice rotundata, venis secundariis paucijugis; folia This content downloaded from 157.55.39.151 on Wed, 13 Apr 2016 15:48:30 UTC All use subject to http://about.jstor.org/terms Volume 3, Number 4 1993 Thomas & Gereau Ancistrocladus korupensis