Arthrinium ibericum Pintos & P. Alvarado

Pintos, Angel, Alvarado, Pablo, Planas, Juan & Jarling, Rene, 2019, Six new species of Arthrinium from Europe and notes about A. caricicola and other species found in Carex spp. hosts, MycoKeys 49, pp. 15-48 : 15

Arthrinium ibericum Pintos & P. Alvarado sp. nov. Fig. 9

Etymology.

In reference to the Iberian Peninsula, where the holotype was collected.

Diagnosis.

Sexual morph: Stromata solitary to gregarious, immersed or semi-immersed, fusiform to ellipsoid in shape, black, with the long axis broken at the top, 2-5 × 0.5-1 mm. Ascomata perithecial, subglobose with a flattened base, arranged in rows, brown to dark brown, exudating a white cirrhus of ascospores, 170-300 µm in diameter and 200-300 µm high. Peridium consisting in 3 or 4 layers of cells arranged in textura angularis. Ostiole single, central, 12-30 µm in diameter, with a periphysate channel. Hamathecium composed of dense, septate, branched paraphyses. Asci 8-spored, clavate or cylindrical, lacking an apical apparatus, shortly pedicelate, measuring (82 –)90–125(– 128) × (14 –)15–19(– 21) μm (n = 30). Ascospores uniseriate to biseriate, hyaline, smooth-walled, apiosporic, composed of a large curved upper cell and small lower cell, fusiform or slightly curved in shape with narrowly rounded ends, uniguttulated, lacking a gelatinose sheath, measuring (28 –)29–34(– 37) × (5 –)6–8(– 9) μm, and a basal cell 5-7 μm (n = 45). Asexual morph: Mycelium hyaline, septate, branched, hyphae 2-4 μm in diameter. Conidiophores reduced to the conidiogenous cells. Conidiogenous cells aggregated in clusters on hypha or solitary, ampuliform or cylindrical, 6-12 × 3 μm. Conidia brown, smooth, globose to ellipsoid (9 –)10(– 12) µm long (n = 30) in face view, lenticular, with a paler equatorial slit, and (6 –)7(– 8) μm long (n = 40) in side view. Sterile cells elongated, rolled up, sometimes mixed among conidia. Culture characteristics: ascospores germinating on MEA 2% within 24-48 h. Colonies flat, spreading, with sparse aerial mycelium, pale siena with white patches.

Type.

Portugal. Viana do Castelo: Valença do Minho, on dead culms of Arundo donax . 10 Jan. 2018, A. Pintos (MA-Fungi 91732 holotype, AP10118 isotype, CBS 145137 ex-type culture).

Notes.

Arthrinium ibericum belongs to the large clade around A. sacchari , where it shows a relation with the subclade of A. phaeospermum , A. saccharicola , and the modern species A. serenense , A. camelliae-sinensis , A. jiangxiense , A. dichotomanthi , A. obovatum and A. pseudosinense . The size of conidia is more or less similar to that of A. camelliae-sinensis , where these measure about 9.0-13.5 μm in frontal view, but conidiogenous cells are a bit smaller in this species, measuring about 4.0-9.5 × 3.0-6.0 μm. Arthrinium pseudosinense has slightly smaller asci measuring 85-100 × 15-20 µm, and ellipsoid conidia covered with a mucilaginous sheath. Arthrinium saccharicola has hyphae slightly wider, about 3-5 µm. The genetic identity of A. phaeospermum is still dubious because of the lack of a proper type, but the lineages of this species in the work of Crous and Groenewald (2013) have slightly smaller conidiogenous cells measuring 5-10 × 3-5 μm, and a different iron-grey colour of colonies in MEA.