Hemitrichia karstenii (Rostafinski) Lister (1894: 178)

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 : 15

Hemitrichia karstenii (Rostafinski) Lister (1894: 178) .

≡ Hemiarcyria karstenii Rostafinski (1876: 41) .

≡ Arcyria karstenii (Rostafinski) Massee (1892: 168) .

≡ Trichia contorta var. karstenii (Rostafinski) Ing (1965: 647) .

Material studied:— UNITED KINGDOM. England: West Midlands, Dudley Castle, January 1891, leg A. Camm, ex Herb. Lister coll. Myzetozoa, B.M. 1489, [BM001247518 = box] (BM). England: West Midlands, Dudley Castle , February 1890 and January 1891, leg A. Camm, ex Herb. H.W. Howard, B.M. 2008, [BM001247518 = box] (BM).

This species is mainly characterized by its branched capillitium with few free ends and filaments with characteristic irregular swellings of globose to oval shape. After studying the type material from Sri Lanka Lister (1894) concluded that is an independent species within the genus Hemitrichia Rostaf. , due to its tangled and branching capillitium of threads with irregular expansions.

On the other hand, this species was combined by Ing (1965) as Trichia contorta var. karstenii , since he did not observe important differential characters with respect to T. contorta , apart from a capillitium with branched elaters and a tendency to form plasmodiocarps . The name Hemitrichia karstenii was accepted by Martin & Alexopoulos (1969), Mitchell (1980) and Flateau (1990). However, it has been cited as Trichia contorta var. karstenii by Lado & Pando (1997), Nannenga-Bremekamp (1991) and Neubert et al. (1993).

To differentiate both taxa, we have analyzed the material of BM under SEM. We observed spiral bands in the capillitium distributed more irregularly in Trichia contorta (Ditmar)Rostaf. and the spore ornamentation is very different between both taxa. Spores of Hemitrichia karstenii have ornamentations of the baculate type, but in Trichia contorta they are of the pilate type. This ornamentation type in T. contorta has also been indicated by Rammeloo (1974) and Neubert et al. (1993) for European material, and by Wang & Li (2006) for Chinese specimens. These sporal differences are sufficient to treat them as autonomous species. Due to the current lack of a full revision for this species group, except for preliminary data on Austral representatives by Ronikier et al. 2020 to confirm its phylogenetic placement, and for the reasons previously stated, we follow Lister and keep it for the time being in the genus Hemitrichia .