Choose the pair of organisms in which dikaryotic stage is formed between plasmogamy and karyogamy and after karyogamy the spores are formed endogenously due to meiosis and free cell formation. 

In Ascomycetes dikaryotic stage intervenes between plasmogamy and karyogamy. In the dikaryotic cells known as asci of ascocarp, the two nuclei fuse (karyogamy) and form diploid nucleus. The nucleus undergoes meiosis and forms four haploid nuclei. These nuclei usually undergo a mitotic division and form eight nuclei. Around each nucleus some amount of cytoplasm is accumulated and secretes a wall to transform into ascospores. Such formation is free cell formation. It is shown by Ascomycetes fungi like Aspergillus, Claviceps, Neurospora and Penicillium.