The lichen, to which the name Lecidea lichenicola is found to have been misapplied, was first described from England and is an extreme specialist of chalk pebbles. It has long been known that it is not closely related to Lecidea in the strict sense, but its true evolutionary relationships have been unknown. Here we use metagenome-assembled genome data to place this fungus in a six-locus phylogeny of Ascomycota, and find strong support for its placement in the class Lichinomycetes. Multiple gene trees using existing data from Lichinomycetes support its further placement within the family Lichinaceae. Based on a revision of types and original descriptions, we conclude that the earliest name for this species is Lecidea obsoleta (syn. Thrombium cretaceum). We neotypify that name by a modern collection and accommodate it in the new genus Watsoniomyces. Type and other original material of L. lichenicola (syn. Discocera lichenicola) was re-examined and found not to be on chalk and to represent a different lichen, Trapelia glebulosa. Watsoniomyces is the first described member of Lichinomycetes with an endolithic thallus.

发现Lecidea lichenicola名称被误用的地衣，最早来自英国，是粉笔石的极端专家。人们早就知道它与严格意义上的Lecidea没有密切关系，但其真正的进化关系一直未知。在这里，我们使用宏基因组组装的基因组数据将这种真菌置于子囊菌门的 6 个基因座系统发育中，并找到对其置于荔枝菌纲中的有力支持。使用荔枝纲现有数据的多个基因树支持其在荔枝科家族中的进一步定位. 根据类型和原始描述的修订，我们得出结论，该物种最早的名称是Lecidea obsoleta（同义词Thrombium cretaceum）。我们通过现代系列对这个名称进行了新类型化，并将其纳入新的Watsoniomyces属。重新检查了L. lichenicola (syn. Discocera lichenicola ) 的类型和其他原始材料，发现它不在粉笔上，而是代表一种不同的地衣Trapelia glebulosa。Watsoniomyces是第一描述构件Lichinomycetes与endolithic菌体。