Armillaria nabsnona

Appearance

The fruit bodies have caps that are initially convex before flattening in age, and reach diameters between 4 and 7 cm . The cap has a smooth surface that becomes sticky when wet. Young specimens can have short, dark hairs on the center. The cap color is brownish, becoming paler towards the edge, and frequently has darker, irregularly shaped bruise spots. The cap margin appears grooved or furrowed due to the thin flesh and the gills underneath. The gills have an adnate to somewhat decurrent attachment to the stipe. They are somewhat distantly spaced, 0.75–1 mm wide, and initially white to cream before darkening to pinkish-tan in maturity. The brownish stipe measures 8–10 cm long by 2–3 mm thick, with a broader base measuring 4–5 mm. It has a ring, and whitish patches of cottony mycelium on its surface below the ring. The ring develops from a dense, white and cottony partial veil that becomes ragged as the cap grows, and sometimes persists as a temporary cortina. Rhizomorphs, if present, are black, branched, and 1–2 mm thick.

The spore print is white. Spores are smooth, hyaline , inamyloid, and have an ovoid to somewhat more or less spherical shape. They typically measure in the range 8–10 by 5.5–6.5 µm. The basidia are club-shaped, four-spored, and 25–35 by 5.5–6 µm, and have a clamp at their bases. Additional basidia may arise from the basal clamp, a branching pattern that distinguishes this species from other ''Armillaria''. This feature becomes less visually prominent as the hymenium matures and neighboring basidia expand and become crowded. The mycelium of the fungus is bioluminescent.

Distribution

The fruit bodies of ''Armillaria nabsnona'' grow in groups, but not clustered together at the base. They are found on hardwood trees in riparian areas. Although it fruits most commonly in autumn, it has been recorded fruiting in the spring in Oregon The range of the fungus was originally described as covering roughly the Pacific Northwest region of North America, including the US states of Washington, Oregon, California, Idaho, Alaska, and the Canadian province British Columbia. In 2008 it was recorded in Hawaii; in 2009, it was reported from Hokkaido Island in northern Japan. Japanese researchers have reported a symbiotic association with the orchid ''Gastrodia elata''.

Habitat

The fruit bodies of ''Armillaria nabsnona'' grow in groups, but not clustered together at the base. They are found on hardwood trees in riparian areas. Although it fruits most commonly in autumn, it has been recorded fruiting in the spring in Oregon The range of the fungus was originally described as covering roughly the Pacific Northwest region of North America, including the US states of Washington, Oregon, California, Idaho, Alaska, and the Canadian province British Columbia. In 2008 it was recorded in Hawaii; in 2009, it was reported from Hokkaido Island in northern Japan. Japanese researchers have reported a symbiotic association with the orchid ''Gastrodia elata''.