Discovery of the first lichenized fungus in the family Chaetothyriaceae ( Ascomycota ), Ceramothyrium ryukyuense sp. nov.

Abstract

Ceramothyrium ryukyuense ( Chaetothyriaceae ) is described as a new species from Okinawa, southern Japan. It is characterized by subglobose minute ascomata (up to 110 μm diam.) covered with a brown mycelial pellicle, small ellipsoid 1(–2)-septate ascospores (8.7–13.8 × 3.4–4.9 μm) within a small ascus (20–30 × 13–17 μm), and a lichenized thallus. This species resembles non-lichenized Brazilian species, C. paiveae and C. philodendri , in producing minute ascomata and 1–4 or 7 septate ascospores. However, besides its lichenized status, C. ryukyuense is distinguished by its smaller asci (up to 30 μm long in C. ryukyuense vs. 30–42 μm long in C. paiveae , and 50–100 μm long in C. philodendri ), and predominantly 1-septate ascospores in C. ryukyuense , whereas multi-septate in C. paiveae and C. philodendri . It was collected on a living leaf of Arecaceae in the subtropical forest near the seashore. In a phylogenetic tree based on nuITS and nuLSU sequences, C. ryukyuense formed a sister clade to Ceramothyrium exiguum which is known as an anamorphic species. DNA sequences of C. paiveae and C. philodendri , morphologically similar species to C. ryukyuense , were not available in this study. Algal cells distant from the perithecium exhibited continuous branching, while those near the perithecium were strongly deformed into a spherical shape and were partially unicellular. The photobiont of C. ryukyuense is suggested to be a species of Trentepohliales , inferred from a phylogenetic analysis based on the rbcl sequence. Ceramothyrium ryukyuense is the first report of a lichenized lineage within Chaetothyriaceae .

Keywords

• arecaceae
• asia
• chaetothyriales
• foliicolous lichen
• lichenization
• subtropics
• symbiosis
• trentepohliales