Diacheopsis mitchellii Nann.-Bremek. & Y. Yamam.

Nannenga-Bremekamp & Yamamoto 1983: Kon. Ned. Akad. Wet., Proc. C 86(2): 224.
Type loc.: Mnt. Kajigamori, Otoyo-cho, Kochi Pref., Japan.

Fructification
Fructification of small groups of sessile, subglobose sporocarps or short plasmodiocarps, ca. 0.4-1 mm Ø, plasmodiocarps up to ca. 2 mm long; steel grey to dark greyisk brown with strong metallic lustre.

Hypotallus
Inconspicuous, thin, membraneous, confluent under a group of sporocarps, in us_sn_19841029 greyish brown and shining.

Peridium
Thin, membranous; splitting irregularly at maturity, but ± persistent; almost hyaline to pale smoky in TL; in RL with bluish to purplish iridescens.

Columella
None.

Capillitium
Rather sparse; thin, 1-3 µm broad threads running from base of sporocarp to peridium, pale to medium greyish/olivaceous brown in TL, pale at extremities; sparsely ± dichotomously branched, with few transverse interconnections; almost smooth or with darker expansions.

Spores
Dark brown to almost black in RL, medium greyish/yellowish brown in TL, globose, 15.5-18.2-20.6 µm Ø; ornamentation of ± cylindrical spines up ca. 2 long, mostly regularly dstributed, many spines appearing ± curved and with 'irregular' apices.

Ecology
The danish finds are from rather different habitats: bark of Betula and Fagus and from podetia of Cladonia.

Distribution in Denmark
Rare. Known from 3 finds: SW- and N-Jutland and N-Zealand.

Global distribution
Known reports from Japan (Nannenga-Bremekamp & Yamamoto, 1983, TYPE), China (Yamamoto et al., 2002) and Great Britain (Ing , 1995 and 1999)

Discussion
The diagnostic character of this taxon is the ornamentation of the spores, described by the original authors (Nannenga-Bremekamp & Yamamoto, 1983) as "... 1.5-1.8 µm long warts, which are sometimes forked or frayed at their apices." The frayed apices was observed in SEM and are so small, that they are below the resolution power of a mainstream light microscope. In sm_sh_sn20060325, however, a certain 'irregularity' is clearly visible with an ordinary oil immersion (100x / na 1.25) lens.

Description
Description based on two collections: us_sn19841029 (herb. C) and sm_sh_sn20060325 (herb. HFG).

 


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.

Diacheopsis mitchellii:
Diacheopsis mitchellii - Sporocarps
Sporocarps (sm_sh_20060325)
Diacheopsis mitchellii - Spores
Spores (sm_sh_20060325)
Diacheopsis mitchellii - Capillitium
Capillitium (sm_sh_20060325)