Amanita: Section Validae, the flavoconioids
Amanita flaviconia, A. erythrocephala, A. elongata, A. flavivolva
Flavoconia and friendsThe most brightly-colored Validae are a cluster of species around Amanita flavoconia. The bright reds, oranges and yellows are most similar to the Caesareae, but those have a well-defined cup at the base of the stalk, while the flavoconia group just have a little rounded knob.
The default Amanita flavoconia has a deep orangey yellow cap, a sort of egg yolk color. The stem also has at least some yellow on it. The ring is small and collapses against the stalk, and turns brown in age.
Amanita flavoconia has a fairly wide range of shades of the above colors, and some of them are part of different species concepts. If your flavoconia-type find is mostly red on top, then you can call it Amanita erythrocephala.
This is a species known from Europe and North Africa, so using this name is sort of doing that bad thing where we find a European name that looks like what we have and use it without checking. But if you want to have a name that actually conveys what your find looks like, this is the best available one.
Going back to more yellow-capped mushrooms, if the cap of your flavoconia-type thing is more of a pure yellow (not orangey) and the stem is white (perhaps under yellow powder), you have Amanita elongata.
Also more yellow-centric is Amanita flavivolva, with a yellow cap that goes “grayish yellow to brownish orange” in the center, and shades almost to white at the edges. The stem is white and bruises “watery brown.”
Traditionally, A. elongata and A. flavivolva have been thought to have fairly disjunct ranges: with elongata known from eastern Canada through North Carolina, and flavivolva only reported from Florida. However, there are some recent reports of elongata from the Gulf Coast. Both of these have undoubtedly been mistaken for flavoconia in the past (and can well be mistaken for each other), so their actual ranges can’t be considered reliable. Flavoconia is known from all over the east – mostly from the Appalachians to the ocean, but also as far west as Minnesota, Missouri and east Texas.
The flavoconia group also have a yellow universal veil, a feature they share with A. flavorubens, A. parcivolvata, A. frostiana, and some color forms of A. muscaria.
There are a number of possible lookalikes to A. flavoconia in the Amanita subgenus: If your flavoconia-type thing is larger and robust, you may have one of our versions of A. muscaria – check for the stack of cogwheel-like rings at the base of the stalk. Likewise, if you’re in the southeast and your flavoconia-type thing is bright red with white flakes and a little knob at the base of the stem, you may have A. parcivolvata. And if the yellow universal veil material on the cap and bulb is powdery and smeared – or if the cap is more of a salmon or apricot color – you may have Amanita wellsii. And if you have what looks like a regular flavoconia but it is striate even when young and its bulb has a real rim with yellow universal veil material on it, you probably have A. frostiana. Because they are in the Amanita subgenus instead of the Lepidella subgenus these three possibilities would all have inamyloid spores.