VEZDAEA ^{1 2}

Gintaras Kantvilas ³

Vezdaea Tscherm.-Woess & Poelt, in D.H. Brown et al., Lichenology: Progress & Problems: 91 (1976).

Type: V. aestivalis (Ohlert) Tscherm.-Woess & Poelt

Thallus crustose, granular to goniocyst-like, sometimes immersed and ± absent. Photobiont Leptosira, with clustered, ± globose to broadly ellipsoid cells 4–10 × 5–6 µm. Ascomata apothecia, immersed, broadly adnate to substipitate, very simple in structure, with the exciple and hypothecium lacking and consisting essentially of asci wrapped in richly branched and anastomosed paraphyses, not bound by hymenial gel. Asci clavate, 8-spored, ± uniformly thick-walled at least when young, with the wall KI+ blue except for a narrow, non-amyloid apical pore. Ascospores simple or transversely septate, ellipsoid, oblong to acicular, hyaline, with a thin, sometimes roughened wall. Conidiomata unknown; conidiogenous cells producing simple conidia, sometimes arising from thallus hyphae and germinating ascospores. Chemistry: nil.

A genus of about 13 species, widely distributed throughout the world. Most species are found overgrowing soil, moribund bryophytes, lichens and plant material or, in the case of one Tasmanian species, endophytically on the moss Dawsonia. Species of Vezdaea are highly inconspicuous, not least because the apothecia are seasonal and short-lived, and reportedly best observed in winter or spring. Several of the European species are associated with mineral-rich sites such as mine tailings or under galvanised fencing.

Key references: Döbbeler (1981); Coppins (1987); Chambers & Purvis (2009).

1	Thallus inconspicuous to absent, growing between the photosynthetic lamellae of Dawsonia; apothecia fleck-like, 35–100 × 10–35 µm; ascospores simple, 7–8 × 3–4 µm	2 V. obscura
	Thallus composed of goniocysts, overgrowing bryophytes; apothecia broadly adnate, roundish, 0.3–1 mm diam.; ascospores 0–3-septate, 12–22 × 5–8 µm	1 V. aestivalis

1 Vezdaea aestivalis (Ohlert) Tscherm.-Woess & Poelt

In D.H. Brown et al., Lichenology: Progress & Problems: 91 (1976); —Lecidea aestivalis Ohlert, Schr. Königl. Phys.-Ökon. Ges. Königsberg 11: 16 (1870).

Thallus dull green to grey-green, composed of minute, contiguous granules and goniocysts overgrowing bryophytes. Apothecia 0.3–1 mm diam., broadly adnate, convex, roundish, grey-brown to dull reddish brown, matt, appearing almost tomentose. Hymenium brownish; asci 70–100 × 14–20 µm; paraphyses 1–1.5 µm wide, of rather uneven thickness and completely enveloping the asci. Ascospores 0–3-septate, ellipsoid-oblong, (12–)13.5–16.6–19(–22) × 5–6–7(–8) µm. Conidia not known.

The inconspicuous and ephemeral habit of this species means that it has almost certainly been frequently overlooked. It appears to be locally common in Tasmania, overgrowing bryophytes on rock walls in urban situations. It is best seen after light, misty rain when the apothecia are swollen with water, but becomes increasingly inconspicuous as the thallus and apothecia dry and shrivel. Superficially, it resembles a species of the Micarea prasina Fr. group, although Micarea differs in its photobiont, thallus chemistry, ascus anatomy and smaller, 0–1-septate ascospores. The ascus-clasping paraphyses in Vezdaea aestivalis are very distinctive and give the asci a “wiggly” outline. This species is widespread in Europe and has also been recorded for mainland Australia (Victoria).

Hobart, St Davids Park, 42°53’S 147°20’E, 15 m, 2018, J. Jarman s.n. (HO); Hobart, Fitzroy Gardens, 42°53'39"S 147°19'10"E, 50 m, 2023, J. Jarman s.n. (HO); Hobart, Marieville Esplanade, 42°53'44"S 147°19'57"E, 2 m, 2023, J. Jarman s.n. (HO).

2 Vezdaea obscura P.Döbbeler

Mitt. Bot. Staatssamml. München 17: 461 (1981). Type: Tasmania [Van Diemens Land], 1844, R.C. Gunn, on Dawsonia superba var. pulchra (holo—M!).

Thallus not apparent, ± absent, immersed within the older, basal leaves of the moss Dawsonia superba. Apothecia immersed between the photosynthetic lamellae on the upper surface of the leaf, visible from above as narrowly elliptical flecks c. 35–100 µm long and 10–35 µm wide, appearing rather verruculose on account of the emergent tips of the asci. Asci 28–42 × 10–13 µm; paraphyses inconspicuous to absent. Ascospores simple, 7–8 × 3–4 µm. Conidia not known.

Known in Tasmania only from the type specimen; also recorded from New Guinea. This is surely Tasmania’s most inconspicuous lichen, consisting solely of clustered asci located between the photosynthetic lamellae of the moss Dawsonia. The host itself is not rare in Tasmania but it has a rather localised distribution, chiefly in the callidendrous rainforests of the north-west. The effort to locate additional specimens of V. obscura on herbarium specimens of Dawsonia proved extremely challenging and ultimately unsuccessful, as the leaves of the moss are inrolled when dry, and the only visible part of the lichen, the apothecia, are minute and unpigmented. The foregoing description is taken directly from Döbbeler (1981) where it is accompanied by fine illustrations.

References