This image attracted me because of the shade of brown in the cross-section of the cap’s skin (pileipellis). It seemed slightly greenish to me. When the image was fully expanded, the appearance of a green tint was largely gone. However, the following hypothesis struck me. We don’t know what combination of pigments appears in the pileipellis of this mushroom. We do know that taxa in the muscaria complex of several pigments including some that are altered by sunlight (in fact one goes from colorless to visibly colored producing some of the dulling down effect in older specimens). The two pigments that impact the color of a freshly opening muscara subsp. muscaria are yellow and purple. Since the colors in Calyptroderma vary (spatially) from the center of the cap outward, it is reasonable to believe that more than one pigment is involved and that the concentration of at least one of the pigments varies from “a lot” to “not much” from the center of the cap outward. It would only take an occasional variation in concentration of one of the pigments to make a color change in the cap. If brown is created by combination of a pigment that we would see as green or bluish and a pigment (or combination of pigments) that we see as orangish. Then increase in the green-blue pigment and/or decrease in the orangish pigment could produce an occasional greenish brown cap. This happens in muscaria. Occasionally the purple pigment is slow to develop (producing buttons that are
strikingly yellow-orange or bright orange-red, but become entirely red with time). Also, just as flower petals can sometimes be striped radially (selective
activation of pigment production), muscaria rarely can be found looking like a tulip with red stripes on a yellow background. Ok, pigment chemists out there. It would be very interesting to hear what you have to say on this.

Rod