Apiosporaceae, Xylariales, Sordariomycetes

DESCRIPTION
Asexual form: Point-like colonies, sometimes confluent and effusive, blackish-brown to black, 100-400 µm in diameter. The mycelium is both superficial and immersed in the substrate; the superficial part is composed of septate, smooth-walled, pale brown to olivaceous hyphae, 2-7 µm thick, branched and anastomosed. The immersed part is sparse, composed of pale olivaceous brown hyphae, 1 to 4 µm thick. The stem cells of the conidiophores emerge on the mat formed by superficial hyphae, and are barrel-shaped or lageniform, measuring 4-8 × 3-6 µm. The conidiophores are erect or erumpent, simple, cylindrical, straight or flexuous, sometimes branched, hyaline, 30-80 µm long and 3-6 µm in diameter, with multiple thick brown to dark brown transverse septa. The conidia are curved, with the ends bent inwards (horn-like), brown to dark brown, with a hyaline germinal cleft. They are smooth-walled, measuring 16-21 × 11-15 µm in frontal view and 8-11 µm thick in lateral view, tapering at the horn ends to 2-4 µm.
The sterile acrogenous cells are hemispherical, pale brown, 5-11 × 5-7 µm in size.
Culture characteristics: Colonies are flat, spread out on MEA medium and have a moderate aerial mycelium, with a yellow underside.

Asexual form is not known.

NOTES
Arthrinium luzulae is the only species with inward-curving conidia. The non-type specimen identified here matches descriptions by Ellis & Ellis (1951), Scheuer (1996) and Minter & Cannon (2018). Genetically, it is related to specimens identified as Ar. curvatum (which have outwardly curved conidia), suggesting that the entire clade containing these samples may have an ancestor with curved conidia (a characteristic not present in other species of Arthrinium).

A. Colony on the surface of the host. B–C. Conidia attached to the conidiophore. D. Conidia in frontal view. E. Aberrant conidia in culture of MEA. F-G. Colony growing on MEA. Scale bars: A = 200 µm, B–E = 5 µm..

HOSPERS
Luzula spadiceae, L. sylvatica.

DISTRIBUTION
Spain, United States, Russia, Switzerland.

BIBLIOGRAFIA
Angel Pintos, Pablo Alvarado. Phylogenetic delimitation of Apiospora and Arthrinium. Fungal Systematics and Evolution. 7. 197-221.
Ellis MB (1965). Dematiaceous Hyphomycetes. VI. Mycological Papers 103: 1–46.
Scheuer C (1996). Neuere Funde von Arthrinium-Arten (Hyphomycetes, Fungi Imperfecti) aus Österreich. Österreichische Zeitschrift für Pilzkunde 5: 1–21. 0

 

Arthrinium Luzulae fungus