Cap 0.8-2.0 cm broad, at first hemispheric, then convex, finally nearly plane, sometimes centrally depressed or with a low umbo; margin incurved, becoming decurved, occasionally wavy, the edge striate; surface dark red to reddish-purple, glossy when moist, hygrophanous, fading with exposure, covered in youth with appressed to slightly raised fibrils, almost glabrous in age; context pale-pink, soft, 2-3 mm thick at the disc, thin towards the margin; odor and taste not distinctive.
Gills adnate to subdecurrent, at first close, subdistant in age, pinkish-vinaceous in youth, soon cinnamon or ochre-brown from spore deposit; gills relatively broad, up to 4 mm in width, edges minutely fringed (use hand lens), lighter than the faces; lamellulae in up to three series.
Stipe 1.5-5.0 cm long, 2-5 mm thick, narrowed slightly towards the base, round to flattened in cross-section, stuffed to hollow; surface fibrillose-striate, pale pinkish-vinaceous at apex, reddish-purple below, white tomentum at the base; context colored like the cap, unchanging; partial veil cortinate, forming a fibrillose zone high on the stipe, often obscure in age.
Spores 6.5-9.5 x 4.0-5.0 µm, smooth, thin-walled, elliptical in face-view, similar in profile, inequilateral, with a flat and curved side, hilar appendage inconspicuous, contents granular; spores cinnamon-brown in deposit.
Solitary or in small groups on rotting stumps and logs of madrone (Arbutus menziesii); known only from coastal regions of California, Oregon, and Washington; fruiting from late fall to mid-winter; rare.
Tubaria punicea is a rare and beautiful mushroom recognized by a dark-red to reddish-purple cap, vinaceous gills that at maturity become ochre-brown to cinnamon-brown from spore deposit, and a vinaceous, fibrillose-striate stipe. Its habit of fruiting on rotting madrone, helps distinguish it from a very closely related species, Tubaria vinicolor (=Naucoria vinicolor) which occurs on woody debris in disturbed habitats, e.g. urban parks. Tubaria punicea should be compared with several unrelated, small reddish mushrooms, the most common of which is Hypholoma aurantiaca, recently reclassified as Leratiomyces ceres. The latter is found abundantly on wood chips, but is more reddish-orange in color, has a pallid colored stipe, and purple-brown spores; the Candy Cap, Lactarius rubidus, bears a resemblance as well, but is terrestrial, not lignicolous, has a milky-watery latex, buff- colored spores, and a pleasing brown sugar odor which intensifies with drying. Two Hygrocybe species, Hygrocybe punicea and H. coccinea could also be confused with Tubaria punicea. They have bright-red caps but differ in waxy gills, a terrestrial habitat, and white spores; another mimic Laccaria laccata var. pallidifolia has a vinaceous cap and somewhat fibrous stipe, but is terrestrial and white spored. Finally several brightly colored Cortinarius species in the subgenus Dermocybe have reddish caps but differ in a terrestrial habit and rusty-brown spores. These include Cortinarius phoenicius var. occidentalis, C. sanguinea, and C. californicus.