Tylopilus rhoadsiae, known by the common name of the Pale Bitter Bolete, is a rare white bolete primarily from the southeastern region of the United States that is often found beneath pine trees. The distinctive features of this species include a mature pore surface and spore print that exhibit a striking pink hue. Further distinctive characteristics of this mushroom includes a nearly white cap and stem, intricate reticulations covering the upper portion of its stem, and non-staining flesh. Lastly, what truly sets Tylopilus rhoadsiae apart is its incredibly potent bitter taste.[i]
Tylopilus rhoadsiae, originally described as Gyroporus badiceps by William Alphonso Murrill in 1940, underwent taxonomic changes over the years. Murrill himself transferred the species to the genus Tylopilus in 1944. Subsequently, in 1942, Wally Snell relocated the species to a newly created genus called Leucogyroporus, which was initially created to contain various species of Gyroporus from the state of Florida. However, the genus Leucogyroporus has since been assimilated into Tylopilus, hence the current name Tylopilus rhoadsiae.
The etymology of this species is straightforward. The genus name “Tylopilus” has Greek and Latin roots. It combines the Greek word “tylos,” meaning “knot” and “pilus,” which refers to the mushroom’s “cap” in Latin. Thus, “Tylopilus” can be interpreted as “mushroom with a swollen cap”. As for the specific epithet “rhoadsiae”, it is a tribute to Dr. Martha E. Rhoads, a renowned American botanist who made significant contributions to the field of mycology.
Identification & Description [iii]
Cap: The cap of T. rhoadsiae is robust and measures 4-20 centimeters in diameter. Initially, the cap has a convex shape during its early stages, which gradually transforms into a broad convex or nearly flat form as it matures. The surface of the cap is typically smooth or has fine hairs and is dry. Its coloration varies from whitish to a very pale gray or tan color. Notably, the cap’s margins projecting beyond the pore surface, extending approximately 1 mm over the edges.
Flesh: The flesh is white. The flesh does not stain when bruised or sliced.
Pores: Being a bolete, Tylopilus rhoadsiae lacks gills commonly found in other mushroom types. Instead, it possesses a hymenium, which forms the spore-bearing undersurface. In this species, the hymenium is noticeably depressed around the stem. Initially white, the pore surface undergoes a transformation as the spores mature, adopting a pale pink coloration. The pores themselves are irregularly circular in shape, number about 1-3 per mm, and are 15 mm deep.
Stem: The stem measures 5-10 centimeters in length and 1-3 centimeters in thickness, and is roughly equal in width throughout its length, although it may taper towards the base. The surface of the stem is dry and shares the same coloration as the cap, ranging from whitish to a very pale grey. Notably, the upper portion of the stem surface displays fine, brown reticulations (a mesh-like pattern).
Spores: The spores of Tylopilus rhoadsiae are smooth, fusiform, hyaline (translucent) to pale yellow, and measure 10–14 by 3.5–5 µm.
Smell: This species does not have a distinct smell.
Flavor and Edibility: Tylopilus rhoadsiae is edible, however, it is very bitter.
Habitat: T. rhoadsiae is mycorrhizal with pines, and is found growing alone, scattered, or gregariously under them.
Range: The distribution of this species is mainly in southeastern United States, especially along the Gulf Coast, like in Alabama, Florida, Louisiana, Mississippi and Texas.
Fruiting season: This species fruits from summer to late fall. Usually from July to September.
Look-A-Likes
There are a few species that can resemble Tylopilus rhoadsiae, each with their own distinct characteristics.
One such species is Tylopilus intermedius. It is found mostly in northern Midwest and the northeastern states, is more likely to be associated with oaks. Tylopilus intermedius can be recognized by its distinctive characteristics, including a stem that appears dirty and stained with a brownish hue. Moreover, the cap surface of Tylopilus intermedius is known for its exceptionally thin “skin,” which becomes more prone to wrinkling and flaking as the mushroom ages.
Another similar species from southeastern United States is Tylopilus peralbidus. This species can be differentiated by its preference for hardwoods, bruising flesh, and smaller spores.
References:
[i] Kuo, M. (2020, October). Tylopilus rhoadsiae.
[iii] Kuo, M. (2020, October). Tylopilus rhoadsiae.
