Didymium trachysporum G. Lister, 1923

Lado, Carlos & Basanta, Diana Wrigley De, 2018, Typification of the myxomycete taxa described by the Listers and preserved at the Natural History Museum, London (BM), Phytotaxa 341 (1), pp. 448-450 : 448-450

Didymium trachysporum G. Lister , Essex Naturalist 20: 113. 1923

— Lectotypus (designated here): UNITED KINGDOM. England, Essex, Leytonstone , 51.569ºN 0.010ºE, 24 Jul 1917 ( BM 2251 A!, BM001089814 + one slide BM s.n.!, 3, BM001223743 ) . Syntypus: UNITED KINGDOM. England, Surrey, Weybridge, in the grounds of St. George’s College , on dead elm leaves, 51.362ºN 0.453ºW, summer and autumn 1922, P.J. Alexander ( BM 2251 B!, BM001095141 ) . Syntypus: UNITED KINGDOM. Scotland, Aberdeen, Westhill , 57.154ºN 2.284ºW, R . Cran ( BM 2251 C!, BM001095142 ) . Syntypus: UNITED KINGDOM. England, Essex, Leytonstone , 51.569ºN 0.010ºE, 25 Jul 1917 ( BM 3228 !, BM001095143 ) . Syntypus: UNITED KINGDOM. England, Surrey, Weybridge, in the grounds of St. George’s College , on dead elm leaves, 51.362ºN 0.453ºW, 1923, P.J. Alexander ( BM s.n.!, BM001095144 ) .

[BM] 2251A / Didymium trachysporum GL / Leytonstone 7.1917. XXXVIII.106/ BM001089814 + one slide 3, BM001223743 [with date “July 24.1917” and reference to the notebook “N.38.106”]. [BM] 2251B Weybridge PJA. XLI. 82./ BM001095141. [BM] 2251 C. Westhill, Aberdeen Cran XXXIV.27/ BM001095142. [BM] 3228 Didymium trachysporum G. Lister / trochus Lister / var. tenue n. var. / Leytonstone 25.7. 17 N. 38.106/ BM001095143. BM s.n. Didymium / trachysporum/ G. Lister/ Weybridge, 1923/ Coll. Alexander/ BM001095144.

NOTES: G. Lister (1923a: 113) described the new species based on material “from near Luton, Bedfordshire on old straw, by Mr. Saunders in 1906; from Lesmoir, Aberdeenshire, on dead grass, by the Rev. W. Cran, in 1913; repeatedly,

in cultures, on old pellets of rabbit and deer, and old bean stalks, Berlin, by Dr. Jahn; from near Vienna, also on deer-

pellets, by Christian Lippert, in about 1895, and from Pornic, Loire Inférieure, on old straw, by M. S. Buchet, in 1912.

In the summer of 1917 it was abundant on old straw manure in our garden at Leytonstone, Essex, and also on straw near Theydon Bois. During the present summer and autumn [1922] the Rev. P. J. Alexander has gathered it repeatedly on dead elm leaves in the grounds of St. George’s College, Weybridge, Surrey.”. In BM we designate BM 2251 A, as the lectotype, as it is in good condition, it has a slide preparation and a notebook reference to notebook XXXVIII: 106

where the species is illustrated and commented upon (XXXVIII: 106A–106B). The illustrations form part of what is reproduced in the publication of the species. There are also notes in notebooks: XXIV: 2–3 (from Saunders, Luton,

Ap. 2.1906), XXXIV: 27 (specimen from W. Cran, Lesmoir, May 31.1913), XLI: 92–92B, 93–94 (specimen from Alexander, Weybridge, 10.1922).

In K 173185 there is material from England, 1917, on old Straw manure?, G. Lister (ex herb. H.J. Howard) and K173186 England, 1919, that could be duplicates of one of the collections.