Yes there are triploid daylilies other than Kwanso and Europa and several other fulva types.
The researchers determined that 'Celtic Sunrise' and 'Forbidden City' are triploids.
Many years ago Arisumi also determined that there were other registered triploids. He found that 'Garnet Robe' is triploid.
Chinese researchers have indicated that 'Baltimore Oriole' is a triploid. In other Chinese research 8% of AHS registered daylilies were identified as triploids by counting chromosomes. That number may be a little high as there is always the possibility that a plant that is being grown as cultivar "X" has been mislabelled somewhere in the production system and is actually a similar but different cultivar with a different ploidy than the true "X". That later research was unable to confirm the triploidy of 'Baltimore Oriole' indicating that it is tetraploid but then indicated that Chicago Apache, Spacecoast Gator Eye, Spacecoast Starburst, Crystal Pinot, Daring Deception, Strawberry Fields Forever, and Moonlit Masquerade are triploids.
There is a current hybridizer and researchers interested in producing triploid daylilies - 'VT Spirit' is their triploid introduction.
It is possible to produce triploid daylilies by simply crossing diploids with tetraploids. That is what Arisumi did. It does require perserverance. He used two techniques. A simple one of crossing them and then planting any mature developed seeds and a more complicated one of opening immature seeds, removing the embryo and growing it in a nutrient medium (called embryo rescue or culture). Both worked and more or less equally. He made 1,607 pollinations. From those he harvested 1,218 seeds. Only 155 of those seeds appeared normal - firm and solid when squeezed. He planted 100 of those seeds normally and 23 germinated to produce 17 triploid plantlets. The remaining 55 seeds were used in embryo culture and produced 12 triploid seedlings. In total there were 17% triploids from normal planting and 21.8% from embryo rescue - about the same success rate.
Although triploids are considered to be sterile most are not 100.0% sterile if enough pollinations are tried (hundreds to thousands). In daylilies triploids tend to be slightly more fertile in crosses with tetraploids but they can also have low fertility with diploids. By making large numbers of pollinations between triploids and diploids it should be possible to produce some viable seeds - probably producing some diploid seedlings. Researchers call this a triploid bridge because it can move genetic characteristics from diploid to tetraploid forms of species in natural conditions.
