Personally I think there are far too few works that explore the 'amorphous nature' of yukkuri anatomy. After all , they need to be able to stretch , distort and warp their bodies quiet a bit to be able to d anything with them. BTW , the larger one could be classified as a dosu , since we have nothing to compare sizes. Especially since in recent times dosu has become to mean 'anything significantly larger than the average yukkuri adult'.
Oh really? Just look at all the stories containing yukkuri (usually Marisas , of course ...) being referred to as Dosu's. I wouldn't make any claims on their actual size , but many aren't that big compared to other yukkuri.
dosus are usually meant to be at least 1 meter and half or 2 meters, the oldes and biggest are 3 meters.
They really are meant to be way bigger than yukkuris, and believe it or not, 1 meter and half is quiete the difference compared to a basketball sized creature.
Oh , I believe it , and certainly in most cases this is what it would amount to , but like many other things about yukkuris it's subject to so many variations that you can't really nail it down. Arguing about stuff like that is meaningless.
Also , I'd like to comment that I like how your yukkuri are coming along , yuyu :-) Can't believe I forgot to mention that :-D Although , I would LOVE to see another installment of 'Poisonous Reimu' ;-)