Auriscalpiaceae - Auriscalpium, Lentinellus and Artomyces

This family has a genus of gilled mushrooms, less common than Russula and Lactarius in the core Russulaceae family of the Russulales. They are an oyster style mushroom, growing on wood with white spores, with their most distinctive character being serrated gill edges when mature. They are not all monomitic, as some have skeletel hyphae making them tougher than the average gilled mushroom (like polypores). They are most easily mistaken for Neolentinus, also with serrated gill edges, and also on wood with white spores, which usually have more central and/or thicker fleshed stems, in the order Gloeophyllales which also contains some dark fleshed polypores.

stems absent or eccentric or fused together, otherwise thin and cartilaginous and seldom more than 5 mm thick (unlike Neolentinus).
Always a boring shade of brown.

The species are told apart by size (caps usually <3 cm vs. ~10 cm), whether or not there is a stem and if those stems all fuse together.

Species mentioned: Lentinellus occidentalis, subargillaceus, flabelliformis, micheneri, cochleatus, umbilicatus, vulpinus, montanus, ursinus, castoreus

These small species (<3 cm across) either have no stem or a very short, stubby lateral stem. They are not sister species and differ microscopically.

Lentinellus occidentalis WA - we have the type sequence, so we know what it is. Its ITS DNA is very similar to other species from different parts of the world, for instance the much older name Lentinellus novae-zelandiae. There may only be a single nucleotide that is reliably different between the two, but for now the morphological differences seem real and the two are not synonymized.

Lentinellus subargillaceus OR - has slightly larger spores (up to 7u vs. 6.2u long but the same width <4.5u) and some cystidia types are shaped differently. We have a CA sequence from Ron Petersen and Karen Hughes, who are the people who placed this species (formerly in Claudopus) in Lentinellus , and are the living authorities for recognizing the species, so I trust the sequence even though we don't have a type sequence.

Lentinellus flabelliformis EU - Ron and Karen note that reports of this EU species in the PNW often turned out to be L. subargillaceus. No confirmed reports have been made since 2004 when the latter species was recombined, and its DNA has never been found in the PNW, so I tend to think that ALL reports of this locally are really something different. If you think you find it, sequence it and help determine once and for all if this species is found here, as we do have EU DNA to compare to. One complication is that this species has been reported with a substantial stem (correctly or not, I don't know) and some even considered it a synonym of the longer stemmed L. micheneri and L. tridentinus, below, but that is now known to be false.

young Lentinellus occidentalis (gill edges entire) © Yi-Min Wang, unsequenced L. occidentalis/subargillaceus group member © A and O Ceska

Small species (caps <5 cm across) with long, relatively ordinary stems

Lentinellus micheneri PN - A small species (<5 cm across) with somewhat distant gills and a fully formed central to off-centre stem that is thin and cartilaginous. Bitter/peppery tasting. This eastern NA species is found out here and in Europe as well, as the DNA appears to match everywhere. Neolentinus kauffmanii is very similar but has closer gills and a slightly thicker stem. We need photographed sequenced collections.

Lentinellus cystidiosus NM - a lookalike not expected in the PNW until a sequence from ID of a supposed L. micheneri turned out to be this. I don't yet know how to tell them apart.

Lentinellus 'tridentinus PNW01' - Our two young collections have strikingly coarse serrations on the gill edges, the gills being distant and thick. When mature, this species might look more like L. micheneri. Perhaps that trait can separate this species from L. micheneri, as some Lentinellus do not show significant gill serration until maturity. Some have synonymized L. micheneri and L. tridentinus (along with L. flabelliformis above), but they are all quite obviously distinct in their DNA, and not all close relatives. L. tridentinus was not suspected from the PNW until DNA showed up in WA 3% different than L. tridentinus of Europe. That species is a complex in the EU with DNA varying by a percent or two, but our sequence is 3% different than any of them and seems to sit quite clearly separate, so it may be in need of a new name.

Lentinellus cystidiosus © Ed Barge, Lentinellus 'tridentinus PNW01' © Lauren Ré and Yi-Min Wang

Lentinellus 'cochleatus PNW02' - This small species (<5 cm across) grows in clusters with the long, thin stems fused together. The caps may be cleft (cochleate). The other clustered species are larger and don't have long stems. Reportedly only on hardwoods. This is a complex of species. There are two sister species in Europe and one in eastern North America (perhaps Lentinellus umbilicatus NY). Our one WA sequence is none of the above and being >3% different from the others, probably needs a new name. I wonder if we might have more than one species here. We could sequence a strongly cleft collection, if we can find one, to see if it's different.

Lentinellus 'cochleatus PNW02' © Yi-Min Wang

Lentinellus vulpinus EU - This large hardwood species (up to 10 cm across) has small, stubby eccentric stems (if any) that are fused together, growing as a tight imbricate clump. It tastes hot and spicy. Petersen found it to be a complex in Europe and North America with some sequences even in Europe differing by up to 7 bp and 2 indels, (most differences are found in ITS2) but with no ecological or morphological differences noted, they are all assumed to be the same species. We have sequences from ID and WA.

Lentinellus montanus ID - This larger species (up to 10 cm across) is stemless but has tan fuzz at the point of attachment (no part of the underside should be without gills, so it's not a true stem) and grows at high elevations in the spring near snowmelt on conifers. It may taste peppery. It was described from Idaho and is more common inland, there and in Montana.

We don't have a type sequence, but we have reliable sequences from OK Miller, the original collector and describer, as well as a modern EWA collection. Interestingly, it is more closely related to the smaller species than it is to its lookalike, L. ursinus. It is monomitic, like the smaller species, which means it's not as tough fleshed as the other large species. These microscopic textural differences are more important phylogenetically than size.

These very similar larger (3-8 cm across) species are also usually stemless but usually grow in fall. Unlike L. vulpinus, they do not grow in very tight clusters. They differ a bit by taste, shape and microscopically. They have been confused with each other in the past, so until a type is selected and sequenced, we will not know for certain that we have sorted out what these sequences are.

Lentinellus ursinus EU - a very spicy tasting conifer and hardwood European species with lots of sequences, most of which match very well to our own sequences (and the rest within a % or so), so I believe this species does occur here. Our two verified sequences with tree association noted were on conifer. Sequenced from ID, WA and OR.

Lentinellus castoreus EU - a usually a mild tasting hardwood species, microscopically different. California sequences are 2% different than Europe, so it's possible that the PNW has an unnamed sister species, if it is found here, but Ron Petersen didn't note any ecological or morphological differences between the continents and for now it's assumed to be all one species. Ron did report it once from WA, so it probably does occur here.