I am no expert but I think it is a setosa. Or to be accurate, some of the images on the database page match a plant that I call setosa.
For comparison here is a range of setosas, including 4 of the 5 named varieties, with that arrow plant at the top left (believe it or not I have a few others).
It becomes a nice little bush when given time and space. I need to get a picture of my biggest clump when it flowers next time. Whether or not this is actually the cultivar called 'Arrow' or 'Arrow Shaped' I am not certain. Some of the images on the net would seem to suggest that arrow name has been applied to a range of plants in the ballpark.
The flowers on my plant match setosa, but I suppose the plant could be a hybrid, something along the lines of Set-Oliver. The database entry for 'Arrow Shaped' does have at least one impostor, which I will move along shortly.
Big appressed sepals = pulvinata in the mix. Looks like 'Doris Taylor' to me.
