In 2017, Tom Blockeel published an article which explained why the species known as U. crispa in Smith’s 2008 moss flora appeared to be ill-defined and readily confused with U. bruchii. Since that then, British and Irish bryologists have slowly been getting to grips with the three species that U. crispa s.l. became – U. intermedia, U. crispula and U. crispa s.str. The Ulota intermedia page compares the 3 species and gives some hints on how to examine peristome characters.
The best time to find and identify U. crispula is when its capsules mature between May and early July. Under the microscope, its inner peristome teeth will distinguish it from U. intermedia and U. crispa, as they have thin cross-walls and partially biseriate segments.
For lots more useful information, Tom’s article is strongly recommended and you can download a PDF by following the link at the bottom of this page.Read the Field Guide account