Microglossum atropurpureum
Anamorph: unknown.
Teleomorph: ascomata 30-50 (-65) mm high and 5-8 (-15) mm diam., often in clusters, irregularly cylindric-clavate, dark purplish brown to dark brown when dry, glossy black to purplish black when wet, with a broad distinct minutely furfuraceous stalk that may be rather short ranging up to two to three times the length of the hymenium. Interascal tissue of unbranched paraphyses 2.5-3.5 µm diam., slightly longer than the asci, thin-walled, hyaline to pale brown, the apical part often somewhat inflated and covered in amorphous purplish brown to brownish matter that agglutinates to form an epithecium. Asci 90–130 x 13–15 µm, narrowly clavate with a fairly long tapering stalk, thin-walled, not fissitunicate, the apex obtuse with a distinct J+ ring, usually 8-spored. Ascospores arranged in an irregular fascicle, 18–32 x 3–4.5 µm, ± cylindrical, with rounded ends and sometimes very slightly tapering towards the base, hyaline, thin-walled, smooth, long remaining aseptate but sometimes 3- to 6-septate when mature (i.e. released from the ascus), without an epispore, gelatinous sheath or appendages.
No formal red list assessment has been made, but the species was included in the BAP scheme and is listed as of conservation priority in England, Wales, Scotland, and Northern Ireland. Along with many other species of unpolluted grassland, M. atropurpureum is assumed to be highly vulnerable to excess nitrogen deposition, and its available habitat has decined markedly in the past fifty years. It is also likely to be vulnerable to under-grazing.
Listed as a species of principal importance to the conservation of biodiversity under Section 41 (England) of the Natural Environment and Rural Communities (NERC) Act 2006; Section 7 of the Environment (Wales) Act 2016; and featured in the Scottish Biodiversity List under Section 2(4) of The Nature Conservation (Scotland) Act 2004; and the Northern Ireland Priority List under the Wildlife and Natural Environment Act (Northern Ireland) Act 2011.
Traditionally classified within Geoglossum (or in a separate genus Thuemenidium), it differs principally by its hyaline rather than dark brown ascospores, and the paraphysis tips within an amorphous dark purple-brown epithecial layer. Microglossum and Geoglossum are very distantly related.
Scattered throughout western and northern Britain, also reported from a number of localities in both Northern Ireland and ROI. Seemingly reasonably common in suitable habitat in western Scotland, less so elsewhere.
In short, unpolluted ("unimproved") grassland on both acid and calcareous soils.