Bricookea sepalorum (Vleugel)M.E. Barr, Mycotaxon 15: 346 (1982)
≡ Metasphaeria sepalorum Vleugel, Svensk bot. Tidskr. 2(4): 369 (1908)

Saprobic on Juncus spp. Sexual state: Ascomata 130– 210μm high, 170–250μm diam., scattered to clustered, gregarious, immersed to semi-immersed under epidermis, becoming erumpent through host tissue, to superficial at maturity, visible as black dots in rows or groups on host surface, uni- to multi-loculate, globose to subglobose, glabrous, dark brown to black, ostioles central, with slit-like opening. Peridium 10–20μm wide, thin-walled, of equal thickness, composed of 2–3 layers of large, brown to dark brown, pseudoparenchymatous cells, arranged in a textura angularis. Hamathecium composed of numerous, 1.5–2μm wide, filamentous, distinctly septate, cellular pseudoparaphyses, embedded in mucilaginous matrix, anastomosing at the apex. Asci (60–)65–75(−80)×12–14(−16) μm (x = 71.5×13.5μm, n=30), 8-spored, bitunicate, fissitunicate, cylindric-clavate, narrowing towards the apex, with subsessile to shortly acute pedicel, apically rounded with well-developed ocular chamber. Ascospores 17.5–19(−21)×6–7.5μm (x = 19×6.4μm, n=30), overlapping 1–2-seriate, phragmosporous, ellipsoidal to broadly fusiform, hyaline to subhyaline, initially forming one median septate, becoming 3-septate at maturity, slightly curved, constricted at the median septum, easily breaking into part spores at the median septum, smooth and thin to thickwalled. Asexual state: Unknown.
Material examined: SWEDEN, Suecia. Holmön, Västerbotten, on dead sepals of Juncus filiformis Linn. (Juncaceae), July 1907, J. Vleugel (S-F49661, type); USA, California, Squaw Valley Creek Meadows, Mt. Shasta, Siskiyou Co. alt. 8,500 ft., on dead sepals of Juncus parryi Engelm. (Juncaceae), 10 July 1947, W. B. Cooke & V. G. Cooke (BPI 737398);Washington, Mt. Baker National Forest, Whatcom Co. Subalpine Meadows along Washington Route #1 near Baker Lodge, on dead sepals of Juncus parryi Engelm. (Juncaceae), 12 July 1948, W. B. Cooke & V. G. Cooke 24247 (BPI 737397); California, King Creek Trail, Lassen Volcanic National Park. alt. 8,000 ft., on dead sepals of Juncus parryi Engelm. (Juncaceae), 1 July 1954 W. B. Cooke & V. G. Cooke 29530 (BPI 737400); California, King Creek Trail, Lassen Volcanic National Park. alt. 8,000 ft., on dead sepals of Juncus parryi Engelm. (Juncaceae), 1 July 1954, W. B. Cooke & V. G. Cooke 29530 (BPI 737399); California, Panther Creek Meadows, Mt. Shasta, Siskiyou Co. alt. 7,600 ft., on dead sepals of Juncus parryi Engelm. (Juncaceae), 4 July 1948, W. B. Cooke 24055 (BPI 737401).

Fig. 1 Bricookea sepalorum (S-F49661, type). a Herbarium label and specimens b Ascomata on substrate. c Section through stroma d Section through peridium. e Asci with cellular pseudoparaphyses strained in cotton blue reagent. f–g Asci. h–i Asci stained in cotton blue reagent. j Ascospores. k–n Ascospores. Scale bars: b=1000μm, c=100μm, e, f, g, h, i, j=20μm, d, k, l, m, n=10μm.