Taylor, (2014) Thaxterogaster caesiolamellatus is a species of fungus in the family Cortinariaceae.

[2] After molecular and morphological evidence suggested that it was sufficiently unique to be considered a unique species, it was promoted to species status in 2014 and classified as Cortinarius caesiolamellatus.

It was placed in the (subgenus Phlegmacium) of the large mushroom genus Cortinarius.

[3] In 2022 the species was transferred from Cortinarius and reclassified as Thaxterogaster caesiolamellatus based on genomic data.

The lengthy fruiting season extends from June (in France) to November (in the United States).