Finding new porcini species with help from citizen scientists

For a while now, I have been on the hunt for new, newly recognized, and long forgotten species of porcini mushrooms. Porcini have been a kind of weird, academic obsession of mine since I started my graduate research way back in 2001 (and I also love to eat them!). Since then I have been slowly accumulating specimens and sequences over the years, but have been reticent with publicizing the information due to the incompleteness of my study. But, science is a decidedly incremental process (especially for me), and sometimes the information needs to be shared to make advances. Also, as much as I’d like to spend most of my time foraging for boletes, I can’t be everywhere at all times, and my career choice has (somewhat ironically) kept me from dedicating more time to fieldwork. So, I’ve turned to friends and colleagues to help source porcini worldwide to include in my expanding dataset. Dan Molter (a.k.a. “shroomydan“) and I have created a citizen science project on MushroomObserver, soliciting specimens of porcini from the broader nonprofessional community. As a way to reciprocate their generosity and efforts, I aim to continuously update a phylogenetic tree based on ITS sequences of these specimens.This is the first installment.

This tree is based on a dataset of 180 hand-curated ITS sequences representing the core Boletus sensu stricto clade (sensu Dentinger et al. 2010; i.e. not including the “alloboletus” group typified by Boletus separans), both from unpublished sequences generated in-house and published sequences captured from GenBank. I built the alignment with the L-INS-i algorithm in MAFFT, partitioned the alignment into ITS1, 5.8S, and ITS2 segments, and used IQTree to find the best ML tree with automatic model selection and ultrafast bootstrapping. I’ve collapsed clades and relabelled them according to my opinion on the current species names that should be applied (with some agnosticism in a few cases). This is subject to change in the near future following a type specimen sequencing study I have been pursuing, but that’s a story for another day. Labels of sequences from MushroomObserver specimens are retained in red and include the original identification supplied by the collector. The species names are color-coded according to geography: red = East Asia, blue = North & Central America, green = Europe, yellow = South Asia, and purple = Australia. In total, I recognize 39 (give or take 2-3) good species of Boletus s.s.

Many thanks to my undergraduate student, Jimmy Arnold for help with this project.