1. Leaf surfaces bullate/foveolate	2
1′. Leaf surfaces flat	3
2. Petioles villose; sepals margins entire; petals 5.5−7 mm long	B. foveolata
2′. Petioles hirsute; sepals margins fimbriate; petals 7.8−8.3 mm long	B. wurdackiana
3. Leaves abaxial and/or adaxial surfaces permanently covered with sessile and short-stalked glands and long unbranched trichomes	4
3′. Leaves abaxial and adaxial surfaces covered with only sessile and short-stalked glands	5
4. Petioles hirsute at the apex; flowers 17−22 mm long; sepals fleshy, with fimbriate margins; petals with entire margins; anther connective with a dorsal appendage	B. formosa
4′. Petioles glandulose-pilose or glandulose-villose throughout; flowers 11−13 mm long; sepals membranaceous, with entire margins; petals margins ciliate at the apex; anther connective unnapendaged	B. maculata
5. Hypanthium covered with sessile or short-stalked glands; sepals with an acute apex; petals 6−6.5 mm long, widely obovate	B. ruschiana
5′. Hypanthium covered with sessile or short-stalked glands and with unbranched trichomes; sepals truncate; petals 7−12 mm, irregularly elliptic	6
6. Flowers 13.3−14.7 mm long; calyx external teeth ca. 1 mm long, triangular, covered with only sessile and short-stalked glands; petals long-apiculate (ca. 1 mm long), the apiculus without an unbranched trichome at the tip	B. duasbocaensis
6′. Flowers 9.5−11.2 mm long; calyx external teeth ca. 2 mm long, ovate, covered with long-stalked glands (0.6−0.8 mm long) and sessile and short-stalked glands; petals short-apiculate (ca. 0.5 mm long), the apiculus with an unbranched trichome at the tip	B. macrocalyx