Systematics and Evolution, Part A The Mycota

Meiosis

♀

/-

Meiospores

♂/+

Meiospores

Eucarpic, Monocentric

Gametophyte

Eucarpic, Monocentric

Gametophyte

Gametangium

Gametangium

Gametes

Gametes

Syngamy

Planozygotes

Planozygotes

Eucarpic, Monocentric

Sporophyte

Eucarpic, Monocentric

Sporophyte

ResistantSporangium

Zoosporangium

Zoospores

Meiosis

♀/-

Meiospores

♂

/+

Meiospores

Holocarpic, Monocentric

Gametophyte

Holocarpic, Monocentric

Gametophyte

Gametangium

Gametangium

Gametes

Gametes

SyngamyPlanozygotes

Holocarpic, Mycelial

Sporophyte

ResistantSporangium

Meiosis

♂

Gametangium

♀

Gametangium

Gametes

Gametes

SyngamyPlanozygotes

Eucarpic, Mycelial

Sporophyte

ResistantSporangium

Eucarpic, MycelialGametophyte

Meiospores

Zoospores

Zoosporangium

Mitosis

Eucarpic, Mycelial

Zoospores Sporophyte

Zoosporangium

ResistantSporangium

Zoospores

Meiosis Syngamy

PlanozygotesEucarpic, MycelialSporophyte

ResistantSporangium

Holocarpic, Monocentric(Cyst) Gametophyte

Zoospores

Zoosporangium

Meiospores(binucleate)

(+)

Gametes

(-)

Gametes

Meiosis

Eucarpic, Mycelial

Meiospores Sporophyte

Zoosporangium

ResistantSporangium

Zoospores

Endomitosis

Meiosis

Eucarpic, MycelialGametophyte

Meiospores

Zoosporangium

ResistantSporangium

Zoospores

Endomitosis

ab

c

d

e

f

g

Fig. 7.6

Diagrams illustrating life cycles and patterns of sexuality in selected

members of Blastocladiomycota. RS, resistant sporangia, TWZ, thin-walledzoosporangia. (

a) Isomorphic alternation of generations, gametophytes het-

erothallic with isogamy, separate sporophytes bear RS or TWZ;

Blastocladiella

variabilis

.(

b) Isomorphic alternation of generations, gametophytes heterothal-

lic with isogamy, sporophyte bearing RS only;

Coelomomyces punctatus

.(

c)

Isomorphic alternation of generations, gametophyte homothallic with anisog-amy, sporophyte with RS and TWZ;

Allomyces arbusculus

.(

d) Heteromorphic

alternation of generations, gametophyte a monocentric cyst with isogamy,

sporophyte produces RS and TWZ;

Allomyces neo-moniliformis

.(

e) Asexual

zoospores give rise directly by mitosis to sporophytes bearing RS and TWZ;some

Allomyces anomalus

.(

f) Meiospores resulting from meiosis in RS

undergo endomitosis at germination to form sporophytes; sporophyte pro-duces RS and TWZ; some

A. anomalus

.(

g) Meiospores resulting from meiosis

in RS give rise to gametophytes bearing TWZ and young RS; endomitosis orselfing in early RS development restores diploid condition;

Catenaria anguil-

lulae

190 T.Y. James et al.