Dothideales » Saccotheciaceae » Saccothecium

Saccothecium rubi

Saccothecium rubi Jayasiri, Wanas., Camporesi & K.D. Hyde, in Li et al., Fungal Diversity 78: 10.1007/s13225-016-0366-9, [24] (2016)

Index Fungorum number: IF 551769; Facesofungi number: FoF 01663

Etymology: In reference to host genus.

Holotype: MFLU 15–3400

Saprobic on dead spines of Rubus ulmifolius Schott. Sexual morph: Ascostromata 94–110 μm high, 110–120 μm diam. (x̄ =98 × 115 μm, n = 10), black, immersed to erumpent, solitary or scattered, globose to subglobose, usually uniloculate, rarely biloculate without a distinct ostiole. Peridium 20–30 μm (x̄ =23 μm, n = 15) wide, a single layer, composed of brown to inner hyaline cells of textura angularis, near the base connected to the host tissue. Hamathecium lacking pseudoparaphyses. Asci 47–62 × 12–16 μm (x̄ = 50 × 15 μm, n = 20), 8-spored, bitunicate, saccate to broadly clavate or cylindric-, with a short bifurcate pedicel and a distinct ocular chamber. Ascospores 14–18 × 4–5 μm (x̄ = 16 × 4.5 μm, n = 25), overlapping biseriate, hyaline, 3-septate, lacking vertical septate, asymmetric, obovoid, fusiform to clavate, with broadly to narrowly rounded ends, with broad upper cells, smooth-walled. Asexual morph: Conidiomata acervular to sporodochial, amphigenous, substomatal, subepidermal, pulvinate, dry or crystaline in appearance, dark brown to black, discrete. Conidiogenous cells on hyaline hyphae, lateral, terminal or intercalary, cylindrical, clavate or globose, integrated, terminal, with holoblastic, polyblastic conidiogenesis, with numerous synchronously produced conidia. Conidia blastic, hyaline, smoothwalled, aseptate, straight, ellipsoidal to sphaerical, reniform to sickle-shaped, sometimes cylindrical with obtuse ends and occasionally with a slightly truncate base, rather variable in shape and size.

            Culture characteristics: Colonies on MEA at 18 °C attaining about 70–80 mm diam. after 14 days, appearing smooth and slimy due to abundant sporulation, pinkish white. Within first 6 weeks’ colonies filamentous and thereafter develop white, setae-like mycelia, then turning to brown and then black at the irregular margin.

Material examined: ITALY, Province of Forlì-Cesena [FC], near Poderone – Corniolo - Santa Sofia, on dead spines of Rubus ulmifolius (Rosaceae), 3 October 2014, Erio Camporesi IT 2136 (MFLU 15–3400, holotype), Ibid., (isotype in KUN); ex-type living culture (MFLUCC 14–1171, KUNCC).

Notes: In this study we have collected a new species of this genus from Italy, with different ascospore and ascus morphology, which also separates in the phylogenetic tree. Wehmeyer (1957) and Holm (1957) proposed to lectotypify the genus with Saccothecium sepincola. Saccothecium has been assigned to Dothideaceae, Dothideales (Barr 1972, 1987 and 2001, Kirk et al. 2008, Lumbsch and Huhndorf 2010, Thambugala et al. 2014). In this study, we could obtain the asexual morph of this species, which is similar to Aureobasidium pullulans (de Bary) G. Arnaud var. (type species of genus Aureobasidium). Hence we can confirm the placement of Saccothecium within family Saccotheciaceae. This is the first record of species from host Rubus ulmifolius in the family Saccotheciaceae (Li et al. 2016).