Molecular work in the genus Hericium.
A handful of attempts have been made towards creating a phylogenetic tree. The biggest point of agreement between them is illuminating that there is a need for work involving larger data sets including international comparisons of what are presently recognized as species. There are also a few collections included that were made outside of their known range of occurrence. These are noted but it is important to be aware not just of their existence but also of the fact that many distribution maps, molecular studies and even libraries of genomic sequences may include them as properly identified samples (for example a Hericium alpestre found in Taiwan was sequenced).
There are a number of specimens reported as having been collected from uncommon hosts. It is presently unclear what may be misidentified collections versus collections found on less common hosts and what part of the outliers may be legitimate discoveries indicating a broader range of occurrence.
There is also a great need for incorporating a broader sampling of all known species from worldwide sources but Australia, Tasmania, New Zealand, Asia and PNW America need extra attention on what is presently considered coralloides or a synonym. In addition to the mess in North America and Europe, there is a softwood lover and a hardwood lover in Asia that need disentanglement.
Published studies of which we are aware:
Hibbett et alia 2000. Nature, 407: 506–508. Evolutionary instability of ectomycorrhizal symbioses in basidiomycetes.
Slippers et alia 2000. Mycologia 92(5): 955–963. Relationships among Amylostereum species associated with siricid woodwasps inferred from mitochondrial ribosomal DNA sequences. [Included Hericium ramosum only as an outlier; gave no indication as to its point of origin.]
Larsson & Larsson 2003. Mycologia, 95(6): 1037–1065. Phylogenetic relationships of russuloid basidiomycetes with emphasis on aphyllophoralean taxa.
Miller et alia 2006. Mycologia, 98(6): 960–970. Perspectives in the new Russulales.
Albee-Scott 2007. Mycological Research, 111(6): 653–662. The phylogenetic placement of the Leucogastrales, including Mycolevis siccigleba (Cribbeaceae), in the Albatrellaceae using morphological and molecular data. [Paper included three Hericium species.]
Das et alia 2011. Cryptogamie, Mycologie, 32(3): 285–293. A new species of Hericium from Sikkim Himalaya India.
Hallenberg et alia 2012. Mycological Progress, 12(2): 413–420. Species complexes in Hericium (Russulales: Agaricomycota) and a new species, Hericium rajchenbergii, from southern South America.
Das et alia 2013. IMA Fungus, 4(2): 359–369. Two new species of hydnoid fungi from India.
Park et alia 2014. Journal of Microbiology & Biotechnology, 14(4): 816–821. Molecular Identification of Asian Isolates of Medicinal Mushroom Hericium erinaceum by Phylogenetic Analysis of Nuclear ITS rDNA.
Chen et alia 2016. Persoonia, 37, 21–36. Global diversity and molecular systematics of Wrightoporia s.l. (Russulales, Basidiomycota).
[Paper included six Hericium species.]
There was also Atila et alia 2018. Journal of Microbiology, Biotechnology & Food Sciences, 7 (5) 532-536. Genetic Diversity of Hericium isolates by ISSRR and SRAP Markers.
However, this last paper appears to have reversed their images of americanum and coralloides (with data suggestive of confusing their samples as well) and the authors cited references that were unconnected to their referenced data. Correspondence with the author indicated that their cultures had been provided with those names.