Meriderma 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 : 204-206

Meriderma sp. Fig. 23

Sporocarps scattered, stipitate, total height (1.12) 1.37–2.82 mm ( Fig. 23A ). Sporotheca globose to subglobose with rounded, broadly conical to conical base, 0.80–1.32(1.56) mm high, (0.70)0.74–1.24(1.34) mm diam ( Figs 23A–B ). Hypothallus thick, red brown, usually small and discoid. Stalk 2/7 to 1/2 of the total sporocarp height, (0.32)0.44– 1.22(1.48) mm long, black, tapering upwards ( Figs 23A–B ). Peridium evanescent, dehiscing in small patches, remaining only at the base of the sporotheca, black, iridescent, with silver and golden reflections under reflected light ( Figs 23A– B ), pale brown, smooth and transparent in transmitted light. Columella reaching 3/7 to 5/8 of the sporotheca height, cylindrical to narrowly clavate ( Fig. 23B ). Capillitium moderately dense, black when spores are blown out, dark brown in transmitted light, with few to many anastomoses in peripheral part and with funnel-shaped ends ( Figs 23B–C ). Spores black in mass, very dark brown in transmitted light, slightly paler at one side, globose, (11)12–14(14.5) μm in total range, 12.97 ±0.6 μm on average ±SD (n = 230), very densely covered with small warts that tend to fuse into lines or even (sub)reticulate pattern ( Figs 23D–G ), spines, ridges and reticulum composed of coralloid elements by SEM ( Figs 23F–G ), ornamentation about 0.5 μm high.

Material examined:— USA. Tehama Co.: Well’s Cabin Campground, 6300 ft., on dead wood, 12 June 1966, DTK 3391, together with L. nigricapillitium (as L. atrosporum, UC 1408219!), on dead twigs, 18 June 1966, DTK 3470, together with L. maculatum (as L. sauteri, UC 1408286!); 3 miles W of Child’s Meadows, 5200 ft., on live cedar, 20 May 1967, DTK 6164 (as L. atrosporum, UC 1408263!); 1 mile S of Lassen Park, 6200 ft., on dead twigs, 28 May 1966, DTK 3281 (as L. sauteri, UC 1408258!); Shasta Co.: Lassen Volcanic Nat. Park, King’s Creek, 7200 ft., on dead twigs, 27 July 1967, DTK 7557 (as L. atrosporum, UC 1408252!); Lassen Volcanic Nat. Park, near Summit Lake, 6700 ft., on bark, 3 July 1967, DTK 6607 (as L. atrosporum, UC 1408253!); on twigs, 2 July 1967, DTK 6551, together with L. maculatum (as L. atrosporum, UC 1408251!); Mt. Rainer Nat. Park, Bench Lake Trail, 4500 ft., on twig, 13 June 1968, DTK 8626 (as L. atrosporum, UC 1408211!); Crater Lake Nat. Park, Cleetwood, 7000 ft., on dead twigs, 7 July 1967, DTK 6822 (as L. atrosporum, UC 1408272!).

Notes:—Most species identified as Meriderma sp. were determined by Kowalski (1970a) as L. atrosporum . Since Kowalski (1975a) circumscribed L. atrosporum as a species with funnel-shaped capillitium ends and spores spiny to reticulate, his interpretation includes most species currently classified within the genus Meriderma (see Poulain et al. 2011). Specimens identified as Meriderma sp. are the collections that do not match any of the described species belonging to the genus. Their spores are densely warted and the warts tend to fuse and are arranged in a subreticulate pattern. In the genus Meriderma there are several non-described morphotypes found in the European mountains ( Poulain et al. 2011). It is very likely that the North American specimens of Meriderma sp. belong to a new species tat is close to an undescribed morphotype, ‘ M. verrucosporum ’. Fresh material suitable for molecular analysis is necessary to revise North American Meriderma specimens. The genus Meriderma requires revision (see, Feng et al. 2016).

Material too scanty to be properly identified to species:

Figures

FIGURE 23. Meriderma sp. A. Sporocarps. B. Open sporocarp. C. Funnel-shaped capillitium tip in transmitted light. D. Spores in transmitted light (edge view). E. Spores in transmitted light (top view). F. Spore by SEM. G. Details of spore ornamentation by SEM. Bars: A–B = 1 mm, C–F = 10 μm, G = 3 μm. A, C: coll. DTK 6551, B: coll. DTK 3281, D–E: coll. DTK 6164, F–G: coll. DTK 6822.