zygosporangium

A zygosporangium is a thick-walled, resting sexual structure produced by certain fungi, primarily within the zygomycetes. It forms during the sexual phase of the life cycle when hyphae of two compatible mating types converge and undergo plasmogamy, followed by karyogamy inside the resulting structure. The enclosed diploid nucleus develops into a zygospore, a durable resting spore that remains dormant for extended periods.

Formation and development occur at the contact points between gametangia from opposing mating types. The gametangial walls break down and a zygosporangial wall develops around the fused cytoplasm, creating a distinct, often globose or irregular body. Inside, the zygospore is typically thick-walled, resistant to desiccation and heat, and can endure unfavorable environmental conditions until germination is favorable again.

Germination of the zygosporangium yields a new sporangiophore-bearing structure that releases sporangia, which contain sporangiospores and reinitiate the asexual phase of the life cycle. In many taxa, meiosis within the zygospore precedes germination, restoring haploid genetic material for subsequent growth. The zygosporangium thus serves as both a conduit for sexual recombination and a durable reservoir that can synchronize reproductive timing with environmental conditions.

Zygosporangia are characteristic of several orders within the Zygomycota, including Mucorales and related groups, with variations in size, shape, and wall composition among species. They play a key role in genetic diversity and ecological resilience for these fungi.