If there is a genus under anther code with the same name then we do indeed use different disambiguators but where there is only one genus is by far the best disambiguator The reader should not have to know beforehand what type of organism it is and should not have to guess what level of the taxonomic hierarchy has been used it could have been Holmia animal Holmia arthropod Holmia trilobite Holmia olenellid Holmia Holmiidae or any number of others Holmia genus is the most predictable most straightforward and broadest disambiguator I have thought about it a lot and I am firmly convinced that this is the best way to disambiguate articles on biological taxa Some of your other questions should be answered at WP DAB especially WP DABNAME Where there is no clear primary topic the disambiguation page is placed at the unqualified title although there should always be a redirect from disambiguation there should never be a redirect from to disambiguation The hatnote at Holmia genus is faulty and should be removed This omission was an oversight