1	Sporangiospores mainly subglobose to globose, ovoid, or irregularly polyhedral	2
–	Sporangiospores mainly ellipsoidal	11
2	Sporangiospores mainly ovoid or irregularly polyhedral	3
–	Sporangiospores mainly subglobose to globose	4
3	Sporangiospores mainly ovoid	B.ovalispora
–	Sporangiospores mainly irregularly polyhedral	B.tuberculispora
4	Azygosporangia subglobose to globose	B.dichotoma
–	Azygosporangia absent	5
5	Chlamydospores abundant in substrate hyphae, in chains	6
–	Chlamydospores absent	7
6	Short sporangiophores simple or rebranched; uni-spored 13.5–23.0 μm; columellae variable in shape, including subglobose, conical, ellipsoidal, cylindrical, hemispherical, near pyriform, or sometimes bell-shaped, long conical	B.chlamydospora
–	Short sporangiophores simple or simple or sympodial; uni-spored 23.5–40.0 μm; columellae hemispherical or conical	B.moniliformis
7	Uni-spored present, subglobose to globose	8
–	Uni-spored absent	10
8	Giant cells present, globose to oval	B.koreana
–	Giant cells absent	9
9	Uni-spored sporangiola are quite common, 18−24 μm in diameter; multi-spored sporangiola 13−33 μm in diameter	B.circina
–	Uni-spored sporangiola are rare, 9−14 μm in diameter; multi-spored sporangiola 14−41 μm in diameter	B.lamprospora
10	Multi-spored sporangiola contain roughly 4–25 sporangiospores, 31.0–59.0 × 33.5–61.5 μm	B.locustae
–	Multi-spored sporangiola contain roughly 5–10 sporangiospores, 14.5–26.0 μm in diameter	B.variispora
11	Chlamydospores abundant	B.solicola
–	Chlamydospores absent	12
12	Giant cells present	13
–	Giant cells absent	15
13	Presence of cylindrical columellae, 62 × 58 µm	B.indica
–	Absences of cylindrical columellae	14
14	Sporangiospores globose to broadly ellipsoid, 8–12 × 7–10 µm	B.dispersa
–	Sporangiospores oblongly ellipsoidal, in young cultures rather uniform, 39.2–40.5 × 14.9–15.5 µm, in ageing cultures smaller spores, 14 × 5 µm and up	B.oblongielliptica
15	Uni-spored rare, globose, up to 15 μm diameter	B.thermophila
–	Uni-spored absent	16
16	Columellae no more than 70 µm	17
–	Columellae up to 70 µm	18
17	Columellae depressed globose to subglobose, apophysate, maximum growth temperature 35 °C	B.fujianensis
–	Columellae usually cylindrical, nonapophysate, maximum growth temperature 32 °C	B.elliptica
18	Presence of pyriform columellae, up to 110 × 75 µm	B.oblongispora
–	Absences of pyriform columellae	19
19	Sporangia up to 250(-300) µm in diameter, columella conical to cylindrical-ellipsoidal, 115–200 × 100–180 µm	B.grandis
–	Sporangia up to 100(-150) µm in diameter, columella applanate conical or cylindrical, 70 × 75 (85 × 100) µm	B.variabilis