Alternaria murispora Ariyawansa & K.D. Hyde, sp. nov.,

Holotype: MFLU 14-0758

Index Fungorum number: IF 550952, 

Etymology: Named after its muriform ascospores.

Saprobic on dead stem. Sexual morph: Ascomata 110–160 × 100–200 μm (= 130 × 150 μm, n = 10), small, scattered, erumpent to (nearly) superficial at maturity, globose or spheroid, dark brown, smooth, apically papillate, ostiolate. Ostiole papilla short and blunt. Peridium 7–15 μm (= 12 μm, n = 10), thin, comprising two cell types, outer layer composed of small heavily pigmented, thick-walled cells of textura angularis, inner layer composed of lightly pigmented or hyaline, thin-walled cells of textura angularis. Hamathecium of 1–2.5 μm (= 1.8 μm, n = 20), cellular, septate, pseudoparaphyses branching and anastomosing between and above asci. Asci 75–106 × 11–16 μm (= 92 × 14 μm, n = 20), (4–6–) 8-spored, bitunicate, fissitunicate, cylindrical to subcylindrical, straight or somewhat curved, with a short, furcate pedicel and minute ocular chamber. Ascospores 16–18 × 5–7 μm (= 17 × 6 μm, n = 40), overlapping seriate, ellipsoid to fusoid, muriform, initially 3-transseptate become 4–5 at maturity, constricted at the central septum, pale brown when immature, dark brown at maturity, without guttules, smooth-walled, with a 1–2.5 μm wide sheath. Asexual morph: unknown.

Material examined: GERMANY, on dead stem, 28 November 2013, A. D Ariyawansa (MFLU 14-0758, holotype).

Notes: Single spore isolation was not successful and therefore DNA was extracted directly from the fruiting body of the fungus. Therefore no living culture is available.

Notes: The novel species Alternaria murispora is introduced here based on both morphology and phylogeny. Alternaria murispora fits in with the general concept of Alternaria in having superficial, globose to ovoid ascomata with short, blunt ostiole, cellular pseudoparaphyses, cylindrical asci with a short, furcate pedicel with ellipsoid to fusoid, brown ascospores slightly constricted at septa. Morphologically A. murispora is closely related to A. conjuncta E.G. Simmons (= Lewia scrophulariae (Desm.) M.E. Barr & E.G. Simmons), but differs in having comparatively smaller asci (75–106 μm versus 120–140 μm), smaller ascospores (16–18 μm versus 23–25 μm) and in the number of septa at maturity (3–5 μm versus 6–7 μm). This is also supported phylogenetically. i.e. A. conjuncta forms a sister clade to A. californica E.G. Simmons & S.T. Koike, while A. murispora forms a sister clade with A. triticina Prasada & Prabhu, in section Infectoriae.

Fig. 1 Alternaria murispora a, b. Ascomata immersed in host substrate. c. Section of ascoma (TS). d. Close up of peridium. e Cellular pseudoparaphyses. f-i. Asci with 8-spores. j-m. Brown ascospores. Scale bars: c-e = 50 µm, f-i = 30 j-m= 10 µm.