Cogniaux' criteria for separation of this species from the common M. macrosperma Mart., the only consistent character seems to be the rather persistent rufo-furfuraceous tomentum (consisting of few-armed stellate hairs and elavate glands) on the branchlets and hypanthium. In M. macrosperma, the hypanthium is nearly or quite glabrous except for the long ± gland-tipped setae, while the stem tomentum is limited to the nodes and lower leaf surface base (although sometimes extending in lines for a short distance below the nodes). In M. lanceolata, the tomentum is evenly distributed on young hypanthia and evenly covers the branchlets on all sides (being tardily deciduous). The ovary apex in M. macrosperma is sparsely to moderately setulose while the recent collections of M. lanceolata show densely setulose ovaries, the hairs in both species being in part simple and gland-tipped or with 1-3 arms from the base. I have examined the Kew syntype (Spruce 2336) of 31. lanceolata, which is in bud (as were apparently the sheets seen by Cogniaux). The only recent collections truly comparable with the original Spruce specimens are Maguire, Cowan, & Wurdack 29956, from the slopes (elev. 800-1100 m ) of Cerro Huachamacari, and Maguire, Wurdack, & Bunting 36805, from the lower slopes of Cerro de la Neblina (alt. 200-650 m). Apart from numerous lowland collections in Guayana, M. macrosperma is also known from the Neblina slopes, alt. 650-700 m (Maguire, Wurdack, & Bunting 36817).