Hydnellum auratile
Hydnellum auratile is a tooth fungus in the family Bankeraceae, first described by the German mycologist Max Britzelmayr in 1891. The fungus produces distinctive orange to orange-brown fruit bodies with caps up to 5 cm wide that fade to brown with age. It forms ectomycorrhizal associations with both coniferous and deciduous trees, particularly Scots pine and Norway spruce on calcareous soils. Though widely distributed across Europe, parts of Asia, Australia, and North America's Pacific Northwest, H. auratile is considered endangered in Switzerland.
Taxonomy
Hydnellum auratile was first described as a species of Hydnum by German mycologist Max Britzelmayr in 1891. Rudolf Arnold Maas Geesteranus transferred it to Hydnellum in 1959.Description
The fruit bodies of Hydnellum auratile arise on a distinct stipe and bear a cap up to 5 cm wide, occurring either singly or in crowded groups. Young caps are vivid orange to orange-brown, with a smooth to slightly scaly surface that feels velvety to the touch. As they mature, fine radial hairs develop and the centre often sinks slightly, creating a shallow, funnel-shaped profile. Concentric wrinkles may appear toward the margin, and the cap colour fades to a muted brownish tone. The flesh is thin—usually no more than 2 mm thick—and mirrors the cap's colour transition from bright orange to pale brown.The stipe reaches about 4 cm in height and 1 cm in width, matching the cap in colour and covered in a similar velvety, felt-like layer of hairs. Under the microscope, the fungus is built of hyphae 2.5–7 μm wide, each separated by simple cross-walls. Its spores are roughly spherical, measuring 5–6 × 3.5–4.5 μm, and are ornamented with tiny wart-like projections. In mass, the spores are brown.
The widespread Hydnellum aurantiacum is a close lookalike, but can be distinguished by having a white to buff cap, dull orange to brown flesh, and white spines.