January 2023 State of LA Fungi
Tuesday, January 24th at 6:30 p.m.
Online discussion using Zoom
Discussion Leader: Rudy Diaz
Program: "Discussion of the mushroom habitat in the Los Angeles area"

The rain kept its promises (and more).

For January 2023, iNaturalist shows a total of 17,606 observations, representing 296 "Research Grade" taxa in Southern California (Fig. 1). Compared to the past five years, we could confidently say that the winter downpour brought at least a three-fold increase in the abundance of macrofungi this January.

In this virtual meeting we discussed desert mushrooms in the Inland Empire, the new taxonomy of Inocybaceae, highlights from Santa Cruz Island, and perspectives on the reality of "species." The recording can be viewed here. The slides can be found here.

In the Inland Empire, Dave G. has been continuing with explorations in the desert. In addition to a number of secotioid Agaricales that have continued to pop up (Disciseda subterranea, Agaricus deserticola, Battarea phalloides, and Tulostoma spp.), a still-unknown omphalinoid mushroom has been observed with moss and other desert shrubs. The difficulty with the identification is that this morphology has evolved independently in two vastly distant groups, Agaricales and Hymenochaetales. Further analysis is required.

We shared an update on the mushroom from Colton Dunes. The more commonly reported dune mushroom in California is Psathyrella ammophila, but the Colton Dunes mushroom seemed slightly different. Following up with microscopy and some taxonomic digging, this mushroom is a good match for Alexander Smith's description of Psathyrella arenulina. This is the first iNaturalist or MushroomObserver observation for Psathyrella arenulina in western North America, but it is probably the case that many interior observations of P. arenulina have been misidentified as P. ammophila; the key distinguishing feature is the absence or presence of pleurocystidia, respectively.

Stu Pickell also shared some highlights from a recent survey of macrofungi on Santa Cruz island. In the chaparral, these include Saproamanita macerisolum, Leucoinocybe lenta, and an undescribed Clitocella sp. Some other interesting mushrooms were found in association with Giant Coreopsis, including undescribed Pleurotus and Ossicaullis spp.

Stepping back and reflecting on the term "species," de Queiroz (2007) points out that the conceptualization has been historically consistent: there is a biological reality to separately-evolving populations, such that individuals express qualities more like close relatives and less like distant relatives. However, the divergence of metapopulations into separate species is a time-bound process without black-and-white simplicity. The scientific disagreements regard where to draw the line for the number of "symptoms" necessary to diagnose metapopulation lineages as separately evolving.

This is not to say perfect should be the enemy of good. In the same way that tracing the outline of a cloud is a convenient fiction for communicating a distribution of vapor in physical space (Fig. 2), tracing the outline of a species is a convenient fiction for communicating a distribution of biological tendencies in genotypic space and phenotypic space.

Strip away the specifics, and the fundamental gap between reality and artificial representations for reality is not just a problem in science, but representational language in general. The statistician George Box remarked on this point that, "essentially, all models are wrong, but some are useful" (1976).

The ratchet of progress in scientific knowledge is our intuition for less wrong.

Rudy Diaz
Resident Mycologist,
Los Angeles Mycological Society

Photo: Stu Pickell
Clavulinopsis sp. and Hygrocybe sp.
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Figure 1. January iNaturalist records for observations of fungi in Southern California (2023 to 2018), total (blue) vs. Research Grade only (green).
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Figure 2. Alternative outlines for the same cloud.
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