Didymium trochus Lister, J. Bot.

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 trochus Lister, J. Bot. 36: 164. 1898

= Didymium vaccinum (Durieu & Mont.) Buchet , in Buchet., Cherm. & Evrard, Bull. Soc. Mycol. France 36: 110. 1920

— Lectotypus (designated here): UNITED KINGDOM. England, Cambridgeshire, Barton , 52.182ºN 0.0562ºE, 8 and 27 Jul 1897, J. Saunders & E. Saunders ( BM 1904 A!, BM001089123 + two slides 1, 3, BM001223744 , BM001223745 ) . Syntypus: UNITED KINGDOM. England, Surrey, Clevelands, Reigate , 51.236ºN 0.230ºW, Apr 1897, E.S. Salmon ( BM 1904 B!, BM001247118 ) . Syntypus: UNITED KINGDOM.England, Bedforshire ,Chaul End, 51.863ºN 0.456ºW, 1 and 6 May 1897 ( BM 1913 !, BM001234117 ) . Syntypus: UNITED KINGDOM. England, Bedforshire , Kitchen End, 52º03’N 0º34’W, 100m, on a “heap of turnips and haulm”, 28 Oct 1897 , C. Crouch ( BM 1708 !, BM 000500869 ) [specimen revised and annotated by Jun Matsumoto, August 12, 1998] .

[BM] 1904A / Didymium trochus List. / vaccinum (Dur. & Mont.) Buchet / Barton 8 & 27.7.97 J&ES[aunders]. NXIV.p.78/ BM001089123. + two slides 1/ Didymium / vaccinum/ (Dur. & Mont.) Buchet/ capm. rigid, hyaline/ Barton.8.7.97/ J&ES NXIVp.78/ BM001223744, and 3/ Didymium / vaccinum/ (Dur. & Mont.) Buchet/ spores irregular /reticulated?/ Barton.8.7.97/ J&ES NXIVp.78 NXIVp.80/ BM001223745. [BM] 1904B / Didymium trochus List. / vaccinum (Dur. & Mont.) Buchet / [Clevelands, Reigate 4.97. E.S. Salmon/ NXIVp.94]/ BM001247118. [BM] 1913 / Didymium trochus List. / vaccinum (Dur. & Mont.) Buchet / Chaul End, Beds. 6.5.97. 1.5.97/ NXIVp.79/ BM001234117. [BM] 1708 [Box only the number. Sheet label: “[BM] 1708/ Didymium ( trochus List. )/ syn. vaccinum (Dur. & Mont.) Buchet / Kitchen End, Beds. Leg C. Crouch 10.97/ J of Bot May’ 98 Pl. 386 fig. 1”]/ BM 000500869 [with a label of revision annotated by Jun Matsumoto, August 12, 1998: Locality: Kitchen End, Beds. On “a heap of turnips and haulm”. Date: October 28, 1897. Leg.: C. Crouch. 1708. This specimen is syntype of Didymium trochus List. ].

NOTES: In describing this species Lister (1898b: 164) noted “We first discovered the species, with both stalked and sessile sporangia, on straw at Chaul End, May 6th, 1897. On July 8th we receive a further supply from Mr. Saunders, gathered in a stackyard at Barton.”, and added further on “On Oct., 28th Mr. C. Crouch sent us a large gathering which he had found on “a heap of turnips and haulm” at Kitchen End, near Ampthill.”, and “In the same month we received from Mr. E. S. Sidmon a small gathering on dead leaves, which he had obtained in April, 1897, in the grounds at Clevelands, Reigate”. In BM we found a box (BM1904) with three samples, (A) from Barton, 8 & 27.7.97 with notes and illustrations in notebook XIV: 78–80. We designate this one as the lectotype as it is one of the materials mentioned by Lister and is in good condition. Sample (B) is the one from “Clevelands, Reigate 4.97. E.S. Salmon/ NXIVp.94”, with notes in notebook XIV: 94, and we consider it to be a syntype. The third sample is from “Warden Hills, 23.9.99”, with a later date so it is not type material. There is also specimen (BM 1913)from Chaul End, Beds. 6.5.97, 1.5.97 with notes in notebook XIV: 79, that is the first material found by Lister (syntype), but he noted that it could be a bit immature and for this reason we dismissed it as the lectotype. The species Didymium trochus Lister is considered to be a synonym of D. vaccinum (Durieu & Mont.) Buchet , as the Listers themselves recognised ( Lister 1925: 113).

In K 173189 there is material from England, 1897, on old straw heap, G. Lister (ex herb. H.J. Howard) that could be a duplicate.