Key 3:

SECTION 3:
Sporangium spherical at first, then angular and upright at maturity, or angular throughout development.

1. On pollen..........................................................................................2
Not primarily on pollen...........................................................................3

2. Sporangium 8-25 micrometers, diameter...............................R. racemosum
Sporangium 80-100 micrometers, diameter..................................R. utriculare

3. On algae or rotifers.............................................................................4
On keratin.............................................................................................6

4. Sporangium angular, with 1-4 discharge papillae.....................................5
Sporangium gibbose, with 1 broad, terminal discharge papilla........R. gibbosum

5. Sporangium with 1-4 projecting discharge papillae, parasitic on Oscillatoria........................................................................R. megarrhizum
Sporangium with 2 broad, opposite discharge papillae, parasitic on various algae...................................................................................R. biporosum

6. From aquatic habitat..........................................................R. nodulosum
From soil habitat....................................................................................7

7. Sporangium angular throughout development........................R. angulosum
Sporangium spherical at first, then angular at maturity................................8

8. Sporangium largest diameter 25 micrometers, 2-5 exit pores.......R. elyensis
Sporangium largest diameter 90 micrometers, 3-25 exit pores....................... .....................................................................................R. venezuelensis

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