The species G. ostrinus that is mention elsewhere was found and named in 1981 and has never been seen or collected since. It's more than likely a synonym of G. lilacinoides. It's described as having a brilliant purple cap turning lilac to pink with age. Unfortunately another amateur has published a photo of G. lilacinoides with purple tints calling it G. ostrinus. With the results that now anything with purple tints is been called G. ostrinus.

Purple tinted G. lilacinoides are common, I know of two places where these are found regularly, yet I have never considered them to be anything more than G. lilacinoides. It reminds me of the saying "Fungi are what they are! Not what you what them to be". That being said I make my fair share of errors and is why I don't intend this website as an identification guide.