Originally described as Ceriomyces zelleri (Murrill 1912) from a collection made in King County, Washington, USA, but known as Boletus zelleri for many years, before being transferred to Xerocomellus (Klofac 2011).

However, work on western North American Xerocomellus (Siegel and Schwarz 2016, Frank et al. 2020) has shown that what was called X. zelleri was in fact the rarer of two different species, and the more common and widespread species, X. atropurpureus was then described. See http://iucn.ekoo.se/iucn/species_view/821024/

Synonyms: Ceriomyces zelleri Murrill, Boletus zelleri (Murrill) Murrill, Xerocomus zelleri (Murrill) Snell, Boletellus zelleri (Murrill) Singer

Xerocomellus zelleri appears to be a rare bolete in western North America, however data on this species is lacking due to confusion with X. atropurpureus; a recently described, and far more common ‘cryptic species’.

Xerocomellus zelleri appears to have a preference for mature and old growth forests, but based on current information, we do not know if it is restricted to such habitat. Until a determination can be made on habitat preferences, and records and trends tracked, we recommend listing it as Data Deficient (DD).

Northern California and Oregon Coast, into the Cascade Range, at least in Washington, into southern British Columbia, Canada.

Population and trends on this species are difficult to delimit, as most records pertain to the once cryptic Xerocomellus atropurpureus. It appears to be restricted to mature and old growth conifer forest, and is still locally common in old growth forests in Olympic National Park and other protected land on the Olympic Peninsula in Washington, USA, but appears to be rare across the rest of its range. Frank et al. (2020) state “Despite extensive collecting over a six-year period in, we encountered this species only five times”.

Although commonly observed in the old growth forest of Olympic National Park, it was not seen close by in the surrounding forests which have been logged. (N. Siegel field observations 2011, 2014, 2016)

Ectomycorrhizal with conifers, often fruiting on and around decaying moss covered stumps and logs, possibly restricted to mature and old growth forest.

Continued loss of old growth forests due to logging and fires.

New records of Xerocomellus zelleri need to be differentiate from X. atropurpureus. Detailed habitat notes with any new observations of this species to describe habitat limitations; tree association and if it needs mature or old growth forests to fruit.

This species is edible, and occasionally collected for food.

Frank, J., Siegel, N., Schwarz, C., Araki, B. and Vellinga, E. 2020. Xerocomellus (Boletaceae) in western North America. Fungal Systematics and Evolution 6: 265-288.

Klofac, W. 1992. Xerocomus chrysenteron und ähnlich aussehende Röhrlinge. Österreichische Zeitschrift für Pilzkunde 1: 19–59.

Murrill, W.A. 1912. The Agaricaeae of the Pacific Coast: I. Mycologia 4 (4): 205–17.

Siegel, N. & Schwarz, C. 2016. Mushrooms of the Redwood Coast. Ten Speed Press: Berkeley, CA. 601 p.