Dendrocollybia pycnoramella is a novel fungal taxa in the process of being described. Since its discovery 2011, it has only been recorded as two mycelia at two sites in California, USA, despite intensive and extensive surveying in appropriate habitats. It is apparently a rare small species but has distinctive and easily recognisable sporocarps with branched stipes. With the few records, not much can be stated about the size of the total population and its status.

It is assessed as Near Threatened based on an estimated of a very small total population estimated not to exceed 150 sites and mature 1500 individuals.

This species is in the process of formal described, and soon will be submitted for publication. A draft manuscript is available upon request from proposing author (Christian Schwarz).

Although this species could be conceivably be confused for the much more common Dendrocollybia racemosa, D. pycnoramella is recognizable by its more densely packed, shorter conidial pegs, irregularly-knobbed sclerotium (vs smooth and round), and straight stipe that emerges directly from the sclerotium (rather than sinuous stipe with a more distant attachment).

Known only from two localities. The type locality was intensively surveyed for the subsequent six years and failed to locate it again.

Extensive surveying along the California coast in similar and marginally similar habitats have failed to find any other sites where this species occurs (despite finding 100+ new sites for its congener D. racemosa).

The congener D. racemosa is the most suitable proxy for understanding detectability and patterns of distribution and ecology (the latter of which cannot be well approximated by other gilled mushrooms). D. racemosa is a species listed for Survey and Management in the Pacific Northwest, and although 100+ sites are known for D. racemosa in Oregon and Washington, only one other location was found (thanks to these surveys).

D. pycnoramella represents a particularly novel evolutionary unit, in that it is the second known species of Dendrocollybia - a formerly monotypic genus.

Given that intensive and extensive targeted surveys (amateur, academic, and state-funded), as well the distinctive appearance of the species have yielded only two localities, we estimate that the number of mature individuals may well be less than 1,000.

Under the D1 criteria for the IUCN Redlist, this species qualifies for Vulnerable (VU) status.

Known from the type locality on the Upper Campus Reserve of the University of California Santa Cruz (California) as well as a location near Murphy (Oregon).

Population distribution and size uncertain due to apparent extreme rarity. Extensive surveying along the California coast in similar and marginally similar habitats since its first discovery in 2011 have failed to find any other sites where this species occurs (despite finding 100+ new sites for its congener D. racemosa). Trendline unknown and impossible to infer from the observations from two locations. Six years of subsequent targeted surveys at the type locality have failed to relocate it. Only one mycelia were recorded each at the two localities. The total number of sites is estimated not to exceed 150 and, assuming 1-2 mycelia on average to occur at each locality, the total number of mature individuals not to exceed 1500.

A sclerotium-forming saprobe specializing on the decaying fruitbodies of other macrofungi (perhaps gilled mushrooms). Likely annual or biennial (one year/growing season to colonize and form sclerotium, fruiting during the second year/wet season).

Habitat at type locality:
A dark, closed-canopy area near a drainage in mixed evergreen forest with a large component of Douglas-fir (Pseudotsuga menziesii), Coast Redwood (Sequoia sempervirens), Tanoak (Notholithocarpus densiflorus), and Interior Live Oak (Quercus wislizenii).

Only known locality of occurrence threatened by increased foot traffic as UC Santa Cruz Campus expands. Presuming that other mycelia occur nearby, primary threat posed is clearance/development of forested land to accomodate expansion of the UC Santa Cruz campus.

Monitoring of known locality to determine whether population is still extant.
Systematic surveys to determine whether other populations exist in similar habitats in California and Oregon.
Outreach to land managers to encourage surveying for this species, and protection of localities in the event that it is found. (1.1; 4.3)

Herbarium collections of the congener Dendrocollybia racemosa should be examined to determine whether there are collections of D. pycnoramella nom. prov. already in herbaria. The short, densely packed conidial pegs on the stipe and the knobby sclerotium should allow for immediate identification. (1.1)

Monitoring of type locality should continue (3) in order to determine whether population from type locality is still extant. Systematic surveys should target this species in order to locate other populations. If and when they are found, fruiting dynamics should be monitored.

Siegel, N and Schwarz, C. Dendrocollybia pycnoramella sp. nov. (unpublished)

Siegel, N and Schwarz, C. 2016. Mushrooms of the Redwood Coast. Ten Speed Press, Emeryville, CA.