Orbilia euonymi Velen., Monogr. Discom. Bohem.

Quijada, Luis, Baral, Hans-Otto & Beltrán-Tejera, Esperanza, 2016, A revision of the genus Orbilia in the Canary Islands, Phytotaxa 284 (4), pp. 231-262 : 234

Orbilia euonymi Velen., Monogr. Discom. Bohem. (Prague): 95 (1934). ( Fig. 2 )

Apothecia 0.2–0.5 mm in diam., up to 0.08 mm high, scattered to subgregarious, deep orange yellow (72. d. OY) to strong yellow brown (74. s. y Br), superficial, disc flat to convex, margin smooth, not protruding. Asci *(41)43– 50(55.3) × 6.7–7.3 μm, †(30)34.5–38(43.7) × 4.2–5.7(6.4) μm; cylindric-clavate, min. ~22-spored, spores 3–5-seriate with 7–10 lower spores inverted (mixed), pars sporifera *15–22 μm; with a partly long and thin, bifurcate base. Ascospores *(3.5)4.2–5.2 × 1.6–1.8 μm, †4–4.8 × 1.5–1.7 μm; ellipsoid-subcylindrical to ellipsoid-clavate, apex obtuse, straight to slightly curved; SBs *1.1–1.7 × 0.3–0.6 μm, tear-shaped to geniculate, apically attached by a short filum. Paraphyses uninflated, cylindrical to slightly clavate, 3–4-septate; terminal cell *(5.5)8–10.3(13.8) × 1.4–2.4 μm, cell below *(4.7)6–7.3(8.8) × 1.4–2.3 μm; unbranched or branched near base; exudate over paraphyses 0.6–2 μm thick, hyaline to pale yellow (89. p. Y), cloddy-like, not firmly attached; apex containing one globose to cylindric SCB *1.4–2.5 × 1.2–1.8 μm. Ectal excipulum at base and middle flanks of textura angularis to t. globosa, *22–34 μm thick; at margin and upper flank of t. angularis to t. prismatica, *9.5–23 μm thick; hyaline to pale orange yellow (73. p. OY), not gelatinized; covered by a continuous medium yellow (87. m. Y) layer of amorphous exudate from upper flank to margin, 0.9–1.7 μm thick. Cells of ectal excipulum *(6.5)8.5–10.5(13) × (4.5)6.5–7.8(10) μm at base and lower flank, wall thickness *0.3–0.6 μm; *(5)6–7.3(8) × 2–3.4 μm at margin, with one globose SCB up to *3 μm diam. in cortical cells at margin.

Specimens examined:— SPAIN. Canary Islands: Tenerife, La Orotava, Teide National Park, Morros Pardos, 28°14’33’’N, 16°38’56’’W, 2456 m, meso-oromediterranean summit broom scrub, on wood of Adenocarpus viscosus branch, 25 April 2013, A. Rodríguez-Romero, L. Quijada & C. Quijada (TFC Mic. 24156!). Guía de Isora, Teide National Park, El Morro los Cerrillos, 28°15’10’’N, 16°42’38’’W, 2010 m, meso-oromediterranean summit broom scrub, on wood of Spartocytisus supranubius , 22 March 2014, R. Negrín, L. Quijada & C. Quijada (TFC Mic. 24549!, 24556!).

Distribution and ecology:— The species was so far only known from the type collection from Czech Republic. A report from United Kingdom is misidentified (see below), as is a report from Asia ( China) which deviates in 64- spored asci and will be assigned to a closely related separate species (Baral et al. in prep.). However, O. euonymi is in fact a frequent species which has been overlooked due to its restriction to xeric wood or rarely bark of various woody angio- and gymnosperms. It occurs all over Europe and also in North America and central Asia (Baral et al. in prep.). Occurring all year round (Baral et al. in prep.). This species was found in Macaronesia above 2000 m in spring season. It grows on the two most common substrates of meso-oromediterranean summit broom scrub ( Adenocarpus viscosus and Spartocytisus supranubius ).

Remarks:— Velenovský provided a short description of Orbilia euonymi in 1934: reddish discoid sessile apothecia, 0.3–0.4 mm diam., asci 25–30 × 6–8 μm, 8-spored, globose ascospores 2–3μ m diam., and filiform branched paraphyses. Hawksworth & Sivanesan (1975) reported a British collection which showed some variation in the colour of apothecia (pale yellowish) and size of ascospores (up to 3.5 μm diam.), and found the asci to be 8-spored in concordance with the protologue. During revision of this collection and Velenovský’s type material of Orbilia spp. by one of us (H.B.), the British collection Hyalorbilia (?) erythrostigma (W. Phillips) Baral & G. Marson, while the holotype of O. euonymi , in which a few apothecia were detected, showed polysporous asci (min. 28-spored) with a rounded apex and apical wall thickening, characters overlooked by Velenovský. The type of ascus apex places this species in subgenus Hemiorbilia (Baral et al. in prep.; for a very similar 64-spored collection see Zhang et al. 2009). The samples from Canary Islands fit quite well the revised species concept as presented in the monograph of Orbiliomycetes (Baral et al. in prep.).

Figures

FIGURE 2. Morphological features of Orbilia euonymi. 1. Rehydrated apothecia. 2. Ascospores: 2a–b. Spore cluster after being released from asci, 2c & 2e. Living ascospores,2d. Dead ascospores.3. Excipular tissues in median section at base and margin.4. Living paraphyses. 5. Living and dead asci. 100 μm= 1a–e; 10 μm= 2a–e, 3a–b, 4a–c, 5a–e, 5g–h; 5 μm= 5f, 5i. Mounted in: CR= 4a, 5d, 5f; H 2 O= 2a–e, 3a–b, 4b–c, 5a–c, 5e, 5g–i. Photos: TFC Mic. 24156= 1a–b, 2a–d, 4a–b, 5d–e, 5h; TFC Mic. 24549= 1c–e, 2e, 3a–b, 5a–b, 5f–g, 5i; TFC Mic. 24556= 4c.