Orbilia hesperidea Rolland, Bull. Soc. Mycol. Fr.

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 : 238-240

Orbilia hesperidea Rolland, Bull. Soc. Mycol. Fr. 17: 118 (1901). ( Fig. 5 )

Apothecia 0.3–0.6 mm in diam., 0.2–0.3 mm high, scattered to subgregarious, deep reddish orange (35. s. r O) to brown-orange (54. br O), slightly erumpent from outer wood fibres, disc flat to slightly convex, margin smooth to slightly crenulate, very slightly protruding. Asci *(54)59–68(75.5) × 5.7–6.6(7.3) μm, †(43)46–58.5(64) × 5–6 μm; dead asci with thickened apical wall (0.8–1.3 μm); cylindric-clavate, 8-spored, spores 4-seriate with 2–4 lower spores inverted, pars sporifera *21–31 μm; with a long thin bifurcate base. Ascospores *(9.5)11.5–12.5(14) × (1.9)2–2.4 μm, †9.5–12.5 × 1.7–2.2 μm; cylindric-clavate to fusiform-clavate, apex obtuse to subacute, straight to inequilateral or medium curved; SBs *(2.3)3–3.5(4.4) × 0.6–1.3 μm, plug- or rod-shaped to subulate, apically broadly attached. Paraphyses cylindrical, slightly to medium clavate to spathulate (rarely lageniform), 3–4-septate; terminal cell *(6)9– 11.7(14.5) × 2.1–3.4 μm, cell below *(7)8.5–10.5(13) × 1.2–2.3 μm; branched at second cell or below; exudate over paraphyses 0.9–2(3) μm thick, hyaline to medium yellow (87. m. Y), continuous or forming broken amorphous clods over paraphyses, not firmly attached, with globose SCBs *1.4–2 μm diam., but also with grayish yellow (90. gy. Y) trapezoid SCBs. Ectal excipulum at base and middle flanks of textura angularis to t. globosa, *(50)64–96(112) μm thick; at margin and upper flank of t. angularis to t. prismatica, *12–30(43) μm thick; hyaline, not gelatinized, with a continuous or broken, deep orange yellow (72. d. OY) to strong yellow (84. s. Y) layer of amorphous exudate from lower flank to margin, 3–10 μm thick. Cells of ectal excipulum *(7)10–11.5(16) × (7)8–9(11.5) μm at base and lower flank, wall thickness *0.3–0.8 μm; *(5.5)7–8.5(12.5) × 2.2–4 μm at margin, with deep yellow (88. d. Y) globose (1.4–2.4 μm diam.), annular (1.6–3 μm diam) and trapezoid (2.3–4.3 × 1.4–3 μm) SCBs.

Specimens examined:— SPAIN. Canary Islands: Tenerife, Fasnia, La Morra los Cardones, 28°14’47’’N, 16°25’47’’W, 346 m, Euphorbia atropurpurea scrub, on wood of Periploca laevigata , 18 December 2013, L. Quijada & C. Quijada (TFC Mic. 24430!). La Laguna, Anaga Rural Park, Andén de la Cruz, 28°34’03’’N, 16°18’06’’W, 337 m, Euphorbia canariensis scrub, on wood and bark of Bystropogon odoratissimus , 20 May 2013, L. Quijada & C. Quijada (TFC Mic. 24233!). Idem, Santa Cruz de Tenerife, Hoya el Laurel, 28°31’53’’N, 16°11’53’’W, 305 m, Euphorbia canariensis scrub, on wood of Periploca laevigata , 5 March 2013, L. Quijada & C. Quijada (TFC Mic. 23914!).

Distribution and ecology:— The species has been reported in the northern hemisphere from Europe ( France). The type grew on wood of Citrus . Without data about phenology ( Rolland 1901), but February on herbarium label. O. hesperidea occurs on xeric wood and bark of both gymno- and angiosperms and is widely distributed in the mediterranean region of Europe but occurs also in semihumid to semiarid regions of North America and Australia (Baral et al. in prep.). Orbilia hesperidea was found in Macaronesia in winter and spring in the Euphorbia scrubs, below 350 m of altitude. It grows on different woody plants, but was never found on succulent species.

Remarks:— The original description gave the asci as 70 × 7 μm and the ascospores as *20 × 4 μm ( Rolland 1901). Rolland saw living ascospores with spore bodies, but his spore measurements are much bigger in comparison to the present range of variation. Re-examination of the holotype by one of us (H.B.) revealed distinctly smaller ascospores (†11.5–14.8 × 2.2–2.9 μm), which better correspond to our samples and also to his uncalibrated drawing: when taking Rolland’s drawn ascus as 70 μm, the spores measure about *12.5–17 × 2.1–2.5 μm.

Orbilia hesperidea can be confused with O. vinosa and O. adenocarpi . All of them have fusiform ascospores, plug- or rod-shaped to subulate spore bodies and a thickened ascus apical wall. Orbilia vinosa has shorter asci (*40–62 μm vs. *54–75.5 μm) and narrower ascospores, usually only up to 1.8–2 μm. Orbilia adenocarpi has longer asci (*61–116 x 5.3–7.6 μm) and longer ascospores (*13.2–30 × 1.7–3.2 μm) ( Quijada et al. 2012).

Figures

FIGURE 5. Morphological features of Orbilia hesperidea. 1. Rehydrated apothecia. 2. Living ascospores. 3. Excipular tissues in median section. 4. Living and dead asci. 5. Living and dead paraphyses. 100 μm= 1a–d; 50 μm= 3a; 10 μm= 2a–b, 3b–c, 4a–d, 5a–b. Mounted in: CR= 4d, 5b; H2O= 2a–b, 3a–c, 4a–c, 5a. Photos: TFC Mic. 23914= 1a–b, 2a, 3c, 4a, 4c–d, 5b; TFC Mic. 24233= 1c–d, 2b, 3a–b, 4b, 5a.