The genus Humidicutis contains approximately eighteen known species worldwide. Nine species, including Humidicutis taekeri, have been recorded in Australia; others are native to North America, Central America and Europe. A collection of photographs of some of the other beautiful Humidicutis species has been published by the Atlas of Living Australia.
Members of the genus are identified primarily by their bright pigments and moist, conical caps (Humidicutis means “moist skin”) that crack radially when fully expanded. Other unifying characteristics include the absence of clamp connections and hymenophoral tramas with short, interwoven hyphae as opposed to parallel hyphae. The fruiting bodies produce smooth, colourless spores larger than 7 μm in diameter, and possess lamellae that are emarginate or adnate but not strongly decurrent.
Humidicutis was originally described by Rolf Singer in 1959. As of the publication of The Agaricales in Modern Taxonomy (3rd ed., J Cramer, 1975), Singer recognized three species: Humidicutis czuica, Humidicutis marginata (and var. olivacea), and Humidicutis rosella. At the time, Humidicutis was classified as a subgenus of Hygrocybe; Humidicutis has since been reassigned as its own genus within the Hygrophoraceae (PDF).
The colourful pigments present in members of Humidicutis were studied by William Ganley Cibula at the University of Massachusetts. In his 1976 doctoral dissertation, The Pigments of Hygrophorus Section Hygrocybe, and Their Significance in Taxonomy and Phylogeny, Cibula reported that Humidicutis spp. characteristically contain polyene pigments, while members of Hygrocybe contain rhodohygrocybin and/or flavohygrocybin pigments.
Daniel adds: For additional (re)reading, the May 2005 BPotD entries have all been updated / repaired / tagged / and so on.