Arcyria imperialis (G. Lister) Q. Wang & Yu Li (2006: 89)

Moreno, G., Castillo, A. & Thüs, H., 2022, Critical revision of Trichiales (Myxomycetes) at the Natural History Museum London (BM), Phytotaxa 567 (1), pp. 1-20 : 14-15

Arcyria imperialis (G. Lister) Q. Wang & Yu Li (2006: 89) .

≡ Hemitrichia imperialis G. Lister (1929: 226) .

Lectotype:— JAPAN. Tokyo Prefecture: Tokyo, gardens of the Akasaka Imperial Palace , 35º40’48”N 139º43’43”E, on Prunus grayana Maxim. , 23 Jan 1928, The Emperor of Japan [Emperor Shôwa, Hirohito] and presented by him to the British Museum, B. M. 4067, [box: BM001085195 , slide: BM001223775 ] ( BM!), as Hemitrichia imperialis G. Lister . Syntype:— JAPAN. Tokyo Prefecture: Tokyo, gardens of the Akasaka Imperial Palace , 35º40’48”N 139º43’43”E, a culture from spores of the typus [see B. M. 4067] obtained by Dr. H. Hattori in the Biological Laboratory, Imperial Palace , Tokyo, 30 Apr 1928, B. M. 4068, [box: BM001085196 , slide:, BM001223776 ] ( BM!), as Hemitrichia imperialis G. Lister .

This species is mainly characterized by a capillitium formed by filaments with 2–3 spirals ornamented with spines on their edges and by its small spores of approx 7 µm in diam. The description is based on the lectotypus specimen, which is in a rather bad condition and we analyzed a small portion of the sporotheca of the lectotype and of the syntype material. The two samples were also studied by Rammeloo (1984). The culture sample B.M. 4068 is in perfect condition and maintains the complete sporocarps and is better preserved than the lectotypus, an assessment already published by Rammeloo (1984) who also pointed out that the ornamentation of the capillitium was somewhat more strongly pronounced in the field collection. However, we found very similar ornamentation of the capillitium in both collections (Figs 1b, f).

Nannenga-Bremekamp (1982) considered Hemitrichia imperialis as a species within the genus Arcyria , but she did not make a valid recombination for this genus and proposed the name as a synonym of Arcyria stipata (Schwein.) Lister. We do not agree with this conclusion because this A. stipata develops filaments of the capillitium with interconnected spiral bands from which spines emerge ( Nannenga-Bremekamp 1991). This morphology clearly differs from what we have observed in the type material of H. imperialis .