Craterium guttatum Gmoshinskiy, 2024

Gmoshinskiy, Vladimir I., Prikhodko, Ilya S. & Novozhilov, Yuri K., 2024, A new species of Craterium (Myxomycetes, Physarales, Physaraceae) with a mottled peridium, Phytotaxa 665 (1), pp. 25-35 : 27-28

Craterium guttatum Gmoshinskiy sp. nov.

MycoBank: MB851528.

GenBank: nrSSU—PP501412; EF1α—PP500999; mtSSU—PP501422; COI—PP501008.

Etymology: from the Latin guttatus —mottled.

Type: — RUSSIA. Kaluga Region: Ulyanovskiy District, Kaluzhskiye Zaseki Nature Reserve, 1.5 km SW from the village of Nagaya, 220 m, 53.55383° N, 35.75550° E, 19 July 2020, linden forest ( Tilia × europaea L.) with birch ( Betula sp. ), Carex pilosa Scop. , Dryopteris filix-mas (L.) Schott, Equisetum sylvaticum L., Ranunculus cassubicus L., Asarum europaeum L., Aegopodium podagraria L., Dicranum undulatum Schrad. ex Brid., Brachitecium sp., Plagiomnium sp. , on the edge of a fen, on small fallen branches, coll. V.I. Gmoshinskiy, I.V. Zemlyanskaya, N.I. Borzov, A.X. Ernandes-Litvinov (holotype MYX 22638!, isotype LE 328535!).

Paratype: — RUSSIA. Vladimir Region: Sudogodskiy District, village of Lobanovo, 120 m, 56.01658° N, 40.81224° E, mixed forest, on Carex sp. and small fallen twigs of Picea abies (L.) H.Karst. 24 July 2020, coll. A.A. Mishulin (MYX 19157!).

Sporocarps scattered, goblet-shaped, round or slightly angular, stalked 0.95–1.25 mm high. Sporotheca 0.4–0.6 mm in diameter, 0.5–0.9 mm high ( Fig. 1 A, B, D, E, H ). Hypothallus usually individual, orbicular, membranous, light orange yellow (l. OY 70) at the periphery and strong orange-yellow (s. OY 68) in the center ( Fig. 1 A ). Stalk deep orange yellow (deep OY 69) to brilliant orange-yellow (brill. OY 67), lighter at the base and darker at the top, membranous, translucent, furrowed, 1/3 of the total height (0.35–0.5 mm high). Peridium rather thick, wrinkled at the base, mottled due to irregular lime deposition, deep brown (deep Br 56) in lower portion brownish orange (brO 54) at the centre, lighter to almost yellowish white (yWhite 92) at the top ( Fig. 1 A, B, D, E, H ). Peridium by SEM clearly triple, composed of closely adhering layers: inner layer membranous, finely warted, middle layer composed of calcareous globules, and outer layer membranous, almost smooth, translucent ( Fig. 2 B–F ). Dehiscence by a well-defined lid, noticeably separated from the rest of the peridium by a preformed line, resulting in a persistent cup with flat or slightly curved outer edges and a convex, calcareous, almost yellowish white (yWhite 92) lid ( Fig. 1 A , Fig. 2 A ). Under SEM, lime on the peridium surface present only along the cup margin and on the lid outer surface as individual spherical granules ( Fig. 2 C, D ). Capillitium dense, retaining the sporocarp shape after spore dispersal and giving it a rough appearance due to many free ends at the periphery ( Fig. 1 C ); lime nodes large, irregular (fig. 2 H, I), white or light yellow (l.Y 86), sometimes forming an irregular central vivid yellow (v.Y 82) pseudocolumella ( Fig. 2 G ). Spores dark brown (d.Br 59) in mass; grayish reddish brown (gy.rBr 46) in transmitted light, with weakly pronounced pale area, occupying up to 1/3 of the spore diameter, globose, (8.1–) 8.6–9.3 (–9.5) μm in diameter (mean= 8.92 μm, SD = 0.33, N = 100), densely minutely warted ( Fig. 1 F, G ). SEM reveals that spores ornamented with groups of small warts with enlarged caputs ( Fig. 2 J, K, L ), represented by several globose thickenings (pilate type by Rammeloo 1975).

Distribution:—in different forests in central and south part of European Russia. However, possibly common in other regions, because Craterium guttatum can be confused with C. leucocephalum or C. minutum which are widely distributed in the world.

Ecology:—on living plants, fallen leaves or small twigs.

Figures

FIGURE 1. Craterium guttatum (A–C, F. Holotype MYX 22638; D, E, G. Paratype MYX 19157). A, B, D, E. Mature sporangia (mottled peridium indicated by arrows). C. Sporocarp, top view. F–G. Spores in transmitted light. Scale bars: A, D = 500 μm, B, C, E = 200 μm, F, G = 10 μm.

FIGURE 2. SEM-micrographs of Craterium guttatum (A–F, L. Paratype MYX 19157. G–K. Holotype MYX 22638). A. General view of the sporocarp. B. Surface of the outer peridium in the calyculus middle part; uneven distribution of lime granules is clearly visible. C. Calcareous surface of the lid. D. Calcareous surface of the upper part of sporangial calyculus. E. Triple-layered peridium. F. Peridium inner surface. G. Fragment of the pseudocolumella. H. Capillitium. I. Calcareous capillitium nodule. J. Details of spore ornamentation. K, L. Warted spores. Scale bars:A = 200 μm, B–E, I = 10 μm, F = 5 μm, G = 20 μm, H = 50 μm, J = 1 μm, K, L = 2 μm.