Pseudoyuconia thalictri (G. Winter) Lar.N. Vassiljeva

[as ‘thalicti’], Nov. sist. Niz. Rast. 20: 71 (1983).

Leptosphaeria thalictri G. Winter, Hedwigia 10: 40 (1872)

Metasphaeria thalictri (G. Winter) Sacc., Sylloge Fungorum 2: 156 (1883)

Scleropleella thalictri (G. Winter) Höhn., Annales Mycologici 18 (1-3): 76 (1920)

Buergenerula thalictri (G. Winter) E. Müll., Sydowia 4 (1-6): 307 (1950)

Pseudoyuconia thalicti (G. Winter) Lar.N. Vassiljeva (1983)

Barrella thalictri (G. Winter) Ahn & Shearer, Can. J. Bot. 73(4): 578 (1995)

Saprobic on dead wood. Ascomata 137–186 ´ 221–137 µm semi-immersed to superficial, globose to subglobose, black. Ostiole central present when mature, ostiolar canal filled with periphyses. Peridium 19–25 µm wide, 3–4 layered, comprising of thick-walled cell, forming a textura angularis. Hamathecium 2–3 µm wide, comprising hyaline, cellular, septate pseudoparaphyses. Asci 80–119 ´ 17–23 µm ( = 97 × 20 µm, n = 20),8-spored, bitunicate, broadly cylindrical or clavate to obovoid, with a minute pedicel, apically rounded end, with an ocular chamber. Ascospores 21–25 ´ 9–12 µm ( = 23 × 11 µm, n = 20), broadly ellipsoidal, pale brown to light brown, 2-septate, slightly constricted at each septum.

Material examined:  RUSSIA, Magadan region, Magadan vicinity, Snow Valley, 8 July 1974, on Thalictrum contortum L. (Ranunculaceae), L. Vasilyeva (VLA P/187).

Notes: Pseudoyuconia, a monotypic genus, was introduced by Vassiljeva (1983) to accommodate Leptosphaeria thalictri G. Winter, and was typified by P. thalictri. Currently, Pseudoyuconia is included in Pleosporaceae (Lumbsch and Huhndorf 2010). No molecular data is available for this genus. Therefore, fresh collections of the type species of the genus are needed so that molecular data can be obtained to verify the natural taxonomic affinities of this genus. Based on the similarities with the other genera of the family Pleosporaceae, such as, in having globose to subglobose ascomata with central ostiole filled with periphyses, peridium composed cells of textura angularis we tentatively place Pseudoyuconia in Pleosporaceae.

Fig 1 Pseudoyuconia thalictri. (VLA, P/187) a. Fungus on host substrate. b. Section through ascomata. c. Close up of the peridium. d. Pseudoparaphyses. e-f. Asci with eight spores. g-j. Ascospores with three septa. Scale bars: b = 100 µm, c, g-j = 10 µm, d = 5 µm, e-f = 50 µm.