Hygrocybe and Camarophyllus/Cuphophyllus have to be split from Hygrophorus to make the genera monophyletic.
The alternative would be to include some other genera in Hygrophorus as well – like Lichenomphalia and Chrysomphalina, and I don’t beleive that is going to happen.

is the currently accepted name on Index Fungorum

http://www.indexfungorum.org/Names/Names.asp

as well as the name used in the recently published “Waxcaps of Eastern North America,” by Bessette, Roody, Sturgeon and Bessette.

I just reviewed this volume for FUNGI mag, and I, too, mourned the loss of the genus Camarophyllus. But, time and taxo marches on…

The nutritional strategies of the clade here:
Conservation of biotrophy in Hygrophoraceae inferred from combined stable isotope and phylogenetic analyses. Seitzman et al., Mycologia, 2010

I’ve known this to bounce back and forth between Camarophyllus russocoriaceus and Hygrophorus russocoriaceus. Desjardin posits it will one day settle in Cuphophyllus. Hygrocybe — though I now see it among the list of synonyms — is not a usage I’m familiar with, yet it has become the prefered name at MO. Last I heard, the fate of the genus placement of these and similar fungi was dependent on some work being done in Europe on their capacity for mycorrhizal relationships.

My question is what makes this Hygrocybe more than any of the other options?

Hygrocybe russocoriacea (Berk. & Jos.K. Mill.) P.D. Orton & Watling, Notes R. bot. Gdn Edinb. 29(1): 131 (1969)

was this placed in Hygrocybe?