Diacheopsis sp.

Ronikier, Anna, 2022, Revision of the Donald T. Kowalski’s collections of Lamproderma (Myxomycetes, Amoebozoa) reveals twice higher species diversity, Phytotaxa 531 (3), pp. 175-210 : 180

Diacheopsis sp. Fig. 4

Three plasmodiocarps present; sessile on a broad base, short to elongate plasmodiocarps 0.36–0.40 × 0.40–1.22 mm, about 0.2 mm high, silvery, shining, with faint colour reflections, without needle-like crystals ( Fig. 4A ). Hypothallus thin, delicate, inconspicuous. Stalk absent. Peridium persistent, attached to capillitium, pale brownish to almost hyaline in transmitted light, surface appearing smooth. Columella absent. Capillitium moderately dense, composed of sinuous, +/- parallel threads with many anastomoses, +/- reticulate, threads 0.5–1 μm wide, smooth or with scattered, round nodes, not widened at junctions, pale brownish in transmitted light ( Figs 4B–C ). Spores dark brown in mass, pale brown in transmitted light, globose to slightly angular in outline, (9)9.5–11 μm in total range, 10.17 ±0.5 μm on average ±SD (n = 30), covered with irregularly distributed warts and groups of darker and denser warts when observed in transmitted light, ornamentation about 0.5 μm high ( Figs 4D–E ). Observation under SEM reveals the ornamentation of irregularly distributed, sometimes loosely and sometimes densely arranged, free cylindrical outgrowths covered at apex by 4–10 small wartlets, connected by an interrupted reticulum ( Figs 4F–I ). Reticulum is probably colourless and thus not observed under light microscope ( Fig. 4E ).

Material examined:— USA. Butte Co.: U.S. 99 & Butte Creek, on plant debris, 9 December 1966, DTK 4093, together with Lamproderma scintillans (as L. scintillans, UC 1408231!).

Notes:—The collection is most likely a new, undescribed species that is the most similar to Diacheopsis vermicularis Nann. -Bremek. & Y. Yamam. It differs from the latter by capillitium that is composed of thin threads with anastomostes, but not forming a net-like structure with expanded junctions, like in D. vermicularis (Nannenga-Bremekamp & Yamamoto 1987). Unfortunately, a single collection of this interesting Diacheopsis composed of a group of three plasmodiocarps growing on a grass culm among a colony of sporocarps of Lamproderma scintillans is not sufficient to describe it as a new species. More material is needed for the formal description of this morphotype.

Figures

FIGURE 4. Diacheopsis sp. A. Plasmodiocarps. B. Capillitium in transmitted light. C. Capillitium by SEM (note uniform threads with anastomoses). D. Spores in transmitted light (edge view). E. Spores in transmitted light (top view). F. Spores by SEM. G–I. Details of spore ornamentation by SEM (note warts covered with wartlets and connected by a reticulum). Bars:A = 1 mm, B–C = 50 μm, D–F = 10 μm, G = 3 μm, H–I—1 μm. A–I: coll. DTK 4093.