Arnium olerum (All Fungi)
Stromata: absent.
Ascomata: 800-1000 µm diam, pyriform, the body globose, ± superficial, covered with tomentose hyaline mycelial hairs, the neck shortly conical, to 300 x 300 µm, periphysate, usually covered with cylindrical thick-walled obtuse hyaline to brown hairs to 100 µm in length. Peridium membanaceous, composed of four layers; the outer of pale brown irregular rather thin-walled textura angularis with cells to 15 µm diam, grading into the innermost layer composed of ± hyaline flattened cells. Interascal tissue consisting of filiform paraphyses, inflated between the septa. Asci 480-500 x 32-38 µm, cylindrical with a long tapering stalk, fairly thin-walled at all stages, the apex rounded, with an indistinct J- apical ring to 7.5 µm diam, 8-spored. Ascospores arranged uniseriately, 40-52 x 25-32 µm, ellipsoidal to broadly fusiform or ovoid, dark brown and thick-walled, smooth, aseptate, with an apical and sometimes also a basal germ pore, and subapical and subbasal elongate gelatinous appendages 30-65 x 10-12 x 7-8 µm in size, flattened in section with alongitudinal furrow, sometimes weakly transversely striate.
Anamorph: not known.
The species is distinctive for its very large ascomata which are covered in hyaline rather than brown hairs, and the very large asci with uniseriate ascospores.
Associated with a wide range of dead herbaceous stems and dung types. In GBI, found on dead stems of Brassica spp., various dung types including that of giraffe, and a rotten hearthrug (Lundqvist, 1972).
GBI: England: Cornwall, London, Norfolk, Northamptonshire, Shropshire, Somerset, Yorkshire. Scotland: unlocalized. Wales: Montgomeryshire (all derived from Lundqvist, 1972)