The leafy stolons of var. monanthos are hollow and can have a slightly swollen appearance in comparison to the typical dichotoma. These stand almost upright on my plants. The flowers are also generally quite a bit smaller and don't have a very wide lower corolla.
Tonys photo is very typical of your average monanthos, quite small and plain looking. The amount of ridges can vary within a population. This feature cannot be reliably used to differentiate between forms of dichotoma.