Diachaea subsessilis Peck (1878: 41)

Moreno, G., Castillo, A. & Thüs, H., 2024, Critical revision of Physarales and Reticulariales (Myxomycetes) at the Natural History Museum London (BM), Phytotaxa 644 (2), pp. 79-101 : 95

Diachaea subsessilis Peck (1878: 41)

Material studied:— ENGLAND. Bedfordshire: Flitwick , Stevens Wood , C. Crouch, 12-9-1897, box B.M. 1705 [ BM001247520 !], + corresponding slide s.n. [ BM001247531 !] .

Material of this species from the same locality, but collected a year earlier, is described by Lister (1897) and his description coincides with the specimen (B.M. 1705) studied here, which was collected a year later. This material was sent to Sturgis for comparison with the American type of D. subssesilis and he considered it identical, but was unable to procure an example of the type, which appears to represent a single gathering, and is now placed in the Fungarium of the New York Botanical Garden (NY).

Although in the protologue ( Peck 1878) this species is described based on sporocarps without columella, we have observed a small columella in the remains of the sample. The presence of a short columella is even seen as part of the distinctive characters for this species by Martin & Alexopoulus (1969). Also, the diameter of the spores in the material seen by us is smaller (9.5 µm) than indicated in the original description (10.16–12.7 µm), although this may be due to the lack of precision of the microscopes of that time. If the taxon seen by us and the one described by Martin & Alexopoulus (1969) really is conspecific with the type material of D. subsessilis remains an open question, as long as the type material has not been revised.