Small groups of subglobose, sessile sporocarps, ca. 0.4-1 mm Ø, or short
plasmodiocarps up to ca. 2 mm long; steel grey to greyish brown in RL,
with metallic lustre, naturally matured sporocarps with shining peridium.
Rather inconspicuous to well developed, confluent under a group of sporocarps,
dull greyish brown, often difficult to see on the dark substrate.
Thin, membraneous; splitting irregularly at maturity; shining or with a more
dim surface in RL, but always with some degree of iridescense, pale
yellowish to smoky in TL, mostely without any distinct ornamentation, but in
one collection (hfg2227) with a faint reticular pattern on the inside.
Profuse, often macroscopically (handlens) visible as a pale, whitish network
in opened sporocarps; of thin 1-3 µm broad threads running ± parallel from
base of sporocarp to perdium, sparsely ± dichotomously branched and with
occasional transverse interconnections, threads mostly ± straight, but
occasionally appearing somewhat undulating; pale to medium yellowish brown
in TL, pale at extremities.
Spores dark bown to almost black in RL, medium to dark greyish brown in TL,
with a distinct, but not very sharply delimited paler area, globose,
(13-) 15-16.2-19 (-21) µm Ø, with very regularly distributed and medium dense,
blunt spines up to ca. 1 µm high.
The plasmodium has not been observed, but immature sporocarps are close to
dark steel grey.
All danish collections have been found during late winter to early spring on
resin-filled wounds on trunks of Picea abies. These wounds result from red deer
trying to access the growth layer beneeth the bark in search for food during
winter time. The wounds are gradually infested with a dark brown imperfect
fungus as well as the ascomycetes Lachnellula cf. resinaria and Sarea resinae.
Known from several plantations in central Jutland and three places
in northern Zealand.
Besides the Danish finds, this taxon has been found in northern France
and in two areas in southwestern Germany.
I have been unable to find a suitable name for this slime mould. However,
beyond doubt it belongs in the genus Diacheopsis. As far as I know only two
currently accepted species of Diacheopsis have spores in the range of this
taxon: D. insessa and D. mitchellii (conf. among others
Neubert et al., 2000
Judging from the original description
(G. Lister, 1913)
D. insessa has spores very similar to the present species, but the capillitium
is described and depicted as sparse, composed of 2-5 µm broad threads and more
irreularly branched with expanded nodes, not of parrallel threads. More recent
descriptions (f.ex. Ing, 1999 and
Rodriguez-Palma & Arturo Estrada-Torres, 1996)
confirm this description.
D. mitchellii has a capillitium similar to this taxon, however, described as
sparse (Nannenga-Bremekamp & Yamamoto, 1983)
and the ornamentation of the spores is very chracteristic and different from
the present one (see Diacheopsis mitchellii).
In view of the differences from the two species mentioned above, and not least
the very special habitat, I am presently most inclined to regard this taxon as
an undesribed species of Diacheopsis.
Description based on 6 collections: hfg2218, 2224, 2227, 2291, 2292 and 2295 (all herb. HFG).
hfg2217, 2225, 2228, 2301, 2383 (all herb. HFG).
N. V. Mogensen introduced me to the locality, where this taxon was first found,
and contributed with additional collections. M. Liebmann and J. Maarbjerg assisted
with microscopical examination before I, myself, had access to a microscope.
Medio January 2020 Bernard Woerly (Northern France) informed me, that he
had found a species of Diacheopsis which conformed almost precisely to
the description given above and with the same ecology. In the time to
follow, Bernard discovered the same taxon on more locaties and late
February he presented a thorough description on his website:
Myxomycètes des Vosges du Nord
Abbreviations: TL : transmitted light; RL : reflected light; Ø : diameter;
TBU : Danish Botanical Topographical District.
Colour-codes refer to: Kornerup, A. & J. H. Wanscher 1974: Farver i farver.
5th reprint. Politikens Forlag, Copenhagen.
When not otherwise indicated spore measurements are given as:
min-mean-max or (extreme-)min-mean-max(-extreme). Spore measurements are exclusive of ornamentation.
Line drawings are free hand sketches.
Distribution maps: Maps of Danish distributions are based on material seen
by the author. World distributions are based on
reports extracted from literature.