Update on INOCYBE SPECIES in the Pacific Northwest

Prepared for the Pacific Northwest Key Council

By Ian Gibson, South Vancouver Island Mycological Society

Copyright ă 2019 Pacific Northwest Key Council


The Pacific Northwest Key Council keys for selected Inocybe species were written by Daniel Stuntz in 1978 by P. Brandon Matheny in 2002 with a revision in 2008). Some species descriptions and a list of references were added to the first key by Ian Gibson in 2004. The two keys were both attempts by experienced observers to make the best use of macromorphology in identification of Inocybe collections. Such identification remains a daunting task, and even experts like to check the microscopic features before making a decision. The less experienced observer is wise to use the microscope or choose another genus.

The purpose of the update is to discuss some new research since 2008 and to provide some additional references. (For convenience the earlier references are included).

Inocybe praecox and Inocybe monticola

Kropp et al. (2010) described two new spring-fruiting species in the Pacific Northwest. They are not easy to identify.

A key was provided for non-reddening North American species of Inocybe with smooth spores and a stem that has metuloid caulocystidia that extend down beyond the mid-point of the stem. If the caulocystidia are visible to the naked eye or with the help of a hand lens, the stem would appear pruinose. Among the species in the key with some evidence of occurrence in the Pacific Northwest are the Inocybe catalaunica group, Inocybe vaccina, Inocybe sindonia, Inocybe kauffmanii, Inocybe laetior, and the two new species mentioned above.

Inocybe chondroderma (the PDAB Inocybe)

Matheny & Griffith (2013) described the common Inocybe chondroderma with the distinctive and useful character that PDAB (p-dimethylaminobenzaldehyde) causes a blue-green reaction with fresh tissue, a reaction otherwise unknown in Inocybe. The species has a cap with a fulvous disk and ochraceous to chamois margin, a cortina, a densely mycelioid stem base, and fall season fruiting, but has been identified as several other species in the past.

Inocybe breviterincarnata, Inocybe occidentalis Inocybe niveivelata

Kropp et al.(2013) described five new species from Utah, including these three. The first two occur also in Washington and the third in montane environments of Washington, Oregon, and Idaho. The first is distinctive and easily recognized in the field because of its pink gills when young. The third has a white silky cap due to abundant veil material and a white stem. The most notable characters are suggested by the names of these two.

Inocybe pallidicremea in the Inocybe lilacina complex

Matheny et al.(2018) found 29 phylogenetic species within the Inocybe geophylla complex. Of these, one monophyletic clade contained Inocybe lilacina and as many as four other species. Inocybe pallidicremea is known to occur in British Columbia, Washington, and Oregon, but none of the others was documented from that area. Inocybe ionocephala occurs as close as the redwood zone of Northern California and Inocybe sublilacina occurs as close as the Colorado Rockies. Inocybe lilacina itself is known from the eastern United States.

Not all lilac species fell within the I. lilacina clade however, and it is not clear which of those might deceive the observer.)

Inocybe ceskae and Inocybe occulta in the Inocybe mixtilis complex

F. Esterve-Raventós et al.(2018) investigated the Inocybe mixtilis complex. Inocybe mixtilis was not found in North America but two of the six species they recognized in the complex were documented from North America. These were Inocybe ceskae and Inocybe occulta, and both were found in the Pacific Northwest. The first is named after Oluna Ceska, a P.N.W. Key Council member who takes a special interest in the genus and contributes numerous collections to the University of British Columbia. The distinction between the two species in their key is that I. ceskae has a cap that is “pale straw-coloured, yellowish beige, pale ochre, slightly sticky in wet conditions” and cystidia <= 50 um, “fusiform, with attenuate but not pedicellate base”, whereas I. occulta has a cap that is “darker , buff yellow, golden-yellow, orange-yellow or light brown, often with a subhygrophanous appearance” and cystidia “often with a sublageniform shape, often extending into a distinct neck, though sometimes variable”, often > 50 um long. They make the general comment about morphological characterization of the species in the complex that characters overlap and it is not always possible to determine the species without studying the DNA.



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