Flora of New Zealand Series

≡Sphaerella assurgens ["asurgens"] Cooke, Grevillea 15: 16 (1886).

=Trichothelium nanum Malcolm & Vězda, Folia Geobot. Phytotax. Praha 30: 95 (1995).

Holotype: New Zealand. Sine loco, on living fronds of Trichomanes venosum, 1885, W. Colenso 2000 – K (M) 57629.

Trichothelium nanum. Holotype: New Zealand. Nelson, York Valley, on Polystichum, 200 m, 19.xi.1993, W. Malcolm 1569. CHR 413966. Isotype. Herb. A. Vězda.

Description : Thallus epiphyllous, rarely hypophyllous, very thin, not easily seen. Perithecia dispersed, globose, 0.1–0.15 mm diam., black, ornamented with setae. Setae whitish, 100–150 μm long, generally 5 in number. External wall black, not covered with thalline tissue. Asci fusiform-cylindrical. Ascospores ellipsoidal, 8 per ascus, 3-septate (rarely 1-septate), 15–20 × 3–3.5 μm.

N: S: Nelson. Known from both type localities on living fern fronds (Trichomanes venosum for T. assurgens, and Polystichum for T. nanum). Known also from eastern Queensland, Victoria and Tasmania (McCarthy et al. 2001; McCarthy 2001i: 157; 2003c), from the Mariana Is – as T. marianense Harada (Harada 1994), and from Hawai'I, the Solomon Is, and Japan (Thor et al. 2000; Lücking et al. 2001; McCarthy 2003b, 2003d).

Palaeotropical

Illustrations : Malcolm & Vězda (1995c: 94, fig. 3 – as Trichothelium nanum); McCarthy (2001i: 155, fig. 42 – as T. nanum).

Trichothelium assurgens is characterised by: the foliicolous habit; small, globose, black perithecia with white setae; and 3-septate ascospores, 15–20 × 3–3.5 μm.