Prototrichia metallica (Berkeley) Massee (1889: 350)

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 : 16-17

Prototrichia metallica (Berkeley) Massee (1889: 350) .

≡ Trichia flagellifera Berkeley & Broome (1866: 56) .

≡ Prototrichia flagellifera (Berkeley & Broome) Rostafinski (1876: 38) .

≡ Prototrichia schroeteri Meylan (1921: 462) .

Material studied:— UNITED KINGDOM. England: Bedfordshire, Luton, 15 April 1908, Miss K. Higgins, B.M. 3174, (BM), as Prototrichia metallica . UNITED KINGDOM. England: Lyme Regis, Charton, 1890-1894, A. Lister, B.M. 1542, [box: BM001247523] (BM), as Prototrichia flagellifera .

This species is characterized by sessile sporocarps (rarely short-stalked), a branched filamentous capillitium with smooth spiral bands and free ends with 3–6 characteristic filiform (penicillate) extremities attached to the upper part of the sporotheca. According to Rammeloo (1983), this species is variable in most of its characters, as reflected in the rather high number of synonyms, but he did not study any of the two samples at BM described here.

Prototrichia schroeteri Meyl. was described as a nivicolous species with fruiting bodies appearing during spring in areas with long lasting snow cover ( Meylan 1921). Morphologically it was further separated from P. metallica by its always stipitate brown sporocarps, by its dense, persistent capillitium, attached to the apex of the stipe that maintains the morphology of the sporocarp once the peridium is lost, by the disconnection of the inner surface of the peridium; and by the colour of the spores.

The morphological differences appear to be mostly ambiguous characters which do not allow a safe separation of the two taxa. If the unusual fruiting time of P. schroeteri was the result of exceptional weather conditions in the collection year or if it really represents a constant character can only be judged based on new and sequenced collections.

The constant presence of a stalk could have been another unambiguous character as all sporocarps from the samples of Prototrichia metallica studied here were sessile. The microscopic characteristics are very similar in both species. However, Kowalski (1975) indicated that he had collected stipitated samples of P. metallica and he concluded that the two names are synonymous, a taxonomic treatment with which we agree, until the separation is re-examined by molecular studies.

The microscopic characters of sample B.M. 1542 assigned to Prototrichia flagellifera are similar to those of sample BM 3174 of P. metallica , so we conclude that the BM-sample is a mislabelled collection of P. metallica . Although we have not studied type material of P. flagellifera , we consider both species synonymous ( Lado 2005 –2022).