That is not four sexes at all. That is a potential speciation event and "weird sex chromosomes." There is still a large gamete and a small gamete and no other t

That is not four sexes at all. That is a potential speciation event and "weird sex chromosomes." There is still a large gamete and a small gamete and no other type of sex cell involved. Two sexes. It's actually pretty sad that this (non-peer reviewed, layperson-written) article got published as-is in Nature. Tetrahymena thermophila has no sexes; it is isogamous. Chromosome configurations are not sexes. But I guess the point of the article is the human interest story, not the subject of the title.