Fungal reproduction: Which spore is produced on a club-shaped structure (basidium) and results from the fusion of two compatible nuclei from different strains of the same fungus?

Introduction / Context:
Different fungal divisions are defined by their sexual structures. Basidiomycota produce sexual spores on club-shaped basidia, a key identification feature.

Given Data / Assumptions:

• “Club” refers to the basidium of basidiomycetes.
• Karyogamy follows plasmogamy to form a diploid nucleus that undergoes meiosis.
• Basidiospores are the resulting sexual spores.

Concept / Approach:
Basidiospores form exogenously on basidia after meiosis. This is different from ascospores (in sac-like asci), blastospores (budding asexual), conidia (asexual), or zygospores (sexual spores of mucoralean fungi).

Step-by-Step Solution:
Identify the “club” as a basidium. Recall that sexual spores on basidia are called basidiospores. Exclude ascospores (asci) and asexual spores (blasto-, conidiospores). Choose “Basidiospore.”

Verification / Alternative check:
Mushrooms, puffballs, and bracket fungi are basidiomycetes producing basidiospores.

Why Other Options Are Wrong:

• Ascospore: Sexual spore of Ascomycota within an ascus.
• Blastospore/Conidiospore: Asexual spores.
• Zygospore: Sexual spore of mucoralean molds.

Common Pitfalls:
Confusing “club” (basidium) with “sac” (ascus).

Final Answer:
Basidiospore.