Arthrinium balearicum 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 balearicum Pintos & P. Alvarado sp. nov. Fig. 3

Etymology.

Refers to the Balearic Islands (Spain), where the holotype was found.

Diagnosis.

Sexual morph: Stromata forming black, linear, confluent raised areas on host surface, with the longer axis broken at the apex, (500 –)600–1500(– 2000) µm × (200 –)320–450(– 500) µm (n = 20). Ascomata globose to subglobose, with flattened base, blackish brown, (120-) 140-180 (-200) µm in diameter (n = 30). Peridium 8-15 µm thick, consisting of 4-5 layers of cells arranged in textura angularis, externally dark brown, hyaline in the inner part. Ostiole single, central, 30-60 µm in diameter, with a periphysate channel 20-30 µm long. Peryphises broad, colourless. Hamathecium composed of dense hypha-like, broad septate paraphyses, deliquescing early, 4-6 µm thick. Asci 8-spored, unitunicate, clavate, broadly cylindrical, with an inconspicuous pedicel, rounded apex, thin-walled, without an apical apparatus, measuring (77 –)80–98(– 105) × (14 –)15–19(– 21) µm (n = 22). Ascospores 1-3-seriate, hyaline, apiospore smooth-walled, fusiform, elliptical, reniform, straight or curved, bicellular, wider at the center of the longest cell, measuring (23 –)26–30(– 32) × (7 –)9–10(– 12) µm (n = 35), basal cell 3-6 µm long, sometimes containing a droplet. Asexual morph: not observed. Culture characteristics: colonies flat spreading on MEA 2%, with moderate aerial mycelium, reverse withish.

Type.

Spain: Balearic Islands: Mallorca, Llucmajor, on undetermined Poaceae , 24 Jan. 2018, A. Pintos (MA-Fungi 91723 holotype, AP24118 isotype, CBS 145129 ex-type culture).

Notes.

Arthrinium balearicum is related with A. descalsii , but has some genetic differences with this species having only 93% (482/518 bp) of its ITS rDNA, 99% (821/823 bp) of 28S rDNA, 97% (688/707 bp) of tef1, and 98% (406/413 bp) of tub2 similar. It is also phylogenetically close to A. phragmitis , a species with a similar ascospore size, (23 –)26–30(– 32) × (7 –)9–10(– 12) µm in A. balearicum and (22 –)23–28(– 30) µm × (6 –)7–9(– 10) µm in A. phragmitis . Unfortunately, the asexual morph of A. balearicum could not be studied to compare it with that of A. phragmitis .