Orbilia vitalbae Rehm

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 : 244-245

Orbilia vitalbae Rehm , in Ade, Hedwigia 64: 315 (1923) ( Fig. 8 )

Apothecia 0.3–0.6 mm in diam., up to 0.2 mm high, subgregarious, medium yellowish pink (29. m. y Pink) to grayish reddish orange (39. gy. R O), superdicial, disc flat to convex, margin finely crenulate and not protruding. Asci *40– 49(53) × (4.1)4.4–4.8 μm, †33–43.4 × 3.5–4.2 μm; apex thin-walled, truncate; cylindric-clavate, 8-spored, spores 2-seriate with 2–3 lower spores inverted, pars sporifera *21–27 μm; with a long thin bifurcate base. Ascospores *6.6–7.2(8) × 1.6–2.1 μm, †6–6.6 × 1.6–1.9 μm; ellipsoid to subcylindrical or fusoid-clavate, apex obtuse to subacute, rarely slightly attenuated at the base, straight to slightly inequilateral; SBs *(3.1)3.7–4.6 × 0.5–0.8(1) μm, pear- to stomach-shaped, apical half filiform to subulate, attached by a narrow or wide point. Paraphyses medium to very strongly clavate-capitate, 2–3-septate; terminal cell *11–19(21) × 3.1–4.3 μm, cell below *8–13(15) × (1.3)1.5–2.1 μm; unbranched or branched below second cell; exudate over paraphyses lacking or up to 0.7 μm thick, grayish yellow (90. gy. Y), continuous and firmly attached; with light gray (264. l. Gray) globose SCBs *0.8–1.6 μm diam. Ectal excipulum at base and middle flanks of textura angularis to t. globosa, *(36)64–78(105) μm thick; at margin and upper flank of t. angularis, *(5)12–16 μm thick; hyaline, not gelatinized, without exudate. Cells of ectal excipulum *(9)11– 13(16) × (7)8.5–10(12) μm at base and lower flank, wall thickness *0.4–0.6 μm; *(5)6.5–7(8.5) × (2.7)4.5–5(6.5) μm at margin; with light gray (264. l. Gray) globose SCBs *0.8–1.6 μm diam.

Specimens examined:— SPAIN. Canary Islands: Tenerife, Vilaflor, Lomo Gordo, 28°10’09’’N, 16°38’11’’W, 1590 m, typical Canary pine woodland, on bark of Sideritis soluta , 9 March 2013, L. Quijada & C. Quijada (TFC Mic. 23937!).

Distribution and ecology:— The species has been reported in the northern hemisphere in Europe ( Germany). Growing on decayed bark of Clematis . Occurring in spring ( Ade 1923, GBIF), but many recent European collections show the species to occur from spring till autumn on various woody or herbaceous substrates (Baral et al. in prep.). By now, this species has only been found once in Macaronesia. It was in spring and on bark of Sideritis in a pine forest above 1500 m of altitude.

Remarks:— Orbilia vitalbae was described by Rehm with ascospores 5–6 × 2–2.5 μm and asci 20–33 × 4.5–5.5 μm ( Ade 1923). The Macaronesian collections differ hereof in longer and narrower spores and asci. A restudy of the lectotype by one of us (H.B.) revealed a very complex case of a mixed collection. The lectotype proposed in Baral et al. (in prep.) shows spores and asci of corresponding length with Macaronesian collections, though distinctly wider, which was also the case in many of the recent European collections studied.

To safely identify this taxon, characters of living specimens, particularly spore bodies, are fundamental. Without this feature O. vitalbae could be confused with other species of Orbilia with a different spore body shape, but with a similar ascospore morphology, such as Orbilia cardui Velen. , O. rosella (Rehm) Sacc. , and O. eucalypti . Since Rehm’s description is without vital elements, the identity of the lectotype is derived based on recent collections on Clematis , which show spore bodies as figured here.

Figures

FIGURE 8. Morphological features of Orbilia vitalbae. 1. Fresh apothecia. 2. Living and dead paraphyses. 3. Living excipular tissues in median section: 3a–b. cells at margin, 3c. cells at base. 4. Living and dead asci. 5. Living and dead ascospores. 100 μm= 1; 50 μm= 3a; 10 μm= 2a–b, 3b–c, 4a–c; 5 μm= 2c–f, 5a–b.All mounted in H2O. All photos from TFC Mic. 23937.