Table 7.

Differentiating features of the R. microsporusgroup and related small Rhizopus species

Organism nameSporangiophore grouping and morphologySporangiospore morphology
R. microsporusvar.rhizopodiformisOccur in singly or in clusters of up to 4Subglobose to rhomboid shape; regular size 4–6 μm; striated and spiny
R. microsporus var. microsporusOccur singly, in pairs, or clusters of 3Rhomboidal shape; regular size 5–6 μm; distinctly striated
R. microsporus var.oligosporusGenerally occur in clustersPleomorphic shapes; variable size 7–10 μm; almost smooth
R. azygosporusGenerally occur in pairs or clustersRound to oval shape; regular size 4–7 μm; faintly striated
R. schipperaeOccur in large clusters of up to 10Subglobose to oval shape; regular size 5 by 7 μm; faintly striated  
Rhizoid morphologyZygospore morphologyOther characteristics
Rudimentary to intensely ramifiedNot knownGood growth at 50°C
SimpleSeen with matingNo growth at 50°C
Simple, with blunt endsNot knownNo growth at 50°C
SimpleAzygospores formed readily within a single isolate; no true zygospores produced; chlamydospores usually produced in abundanceGlabrous growth without sporulation seen at 50°C; optimal sporulation and azygospore formation between 25 and 37°C
Simple, rarely branchedNot knownNo growth at 50°C; produces abundant chlamydospores and fails to sporulate on routine fungal media