Allocetraria denticulata (Hue) Thell & Randl.
Nomenclatural data
Basionym: Cetraria denticulata Hue, Nouv. Archiv. Mus.. (Paris), 4, I: 85, 1899. - Type: China, Yunnan, Yen-tze-hay, Delavay, on ground, 08.08.1888 (holotype - not available in PC)
Morphology
Thallus greenish-yellowish, foliose, erect, 2–3 cm long, flattened at the bases and caespitose; lobes 0.8–1.5 mm broad, apically indented and with marginal projections along the margins; marginal projections at their tops either whitish or bearing pycnidia or small spines. Upper surface smooth, plane or somewhat convex; lower surface similar to the upper or slightly brownish and somewhat concave. Upper cortex presumably paraplectenchymatous, 25–60 µm, richly incrusted with crystals; lower cortex similar to the upper but more white, with fewer cells and crystals not as frequent. Algal cells 5–6 µm broad, in clusters. Medulla 25–60 µm thick with 3.5–5.5 µm broad hyphae.
Apothecia unknown. Pycnidia on marginal emergent projections, small, black; conidiophores 2–3 celled, pycnoconidia filiform of somewhat different appearances, 12–15 x 1 µm.
Chemistry
Chemical compounds unknown, but obviously usnic acid in the cortex.
Remarks
This species is known only from the type collection; it was described from China by Hue (1899) and probably forgotten later, mentioned again only by Wei (1991). Unfortunately, we have not seen any material of this taxon but according to the careful Latin diagnosis it should definitely be included in Allocetraria. This species seems to be well separated from other taxa according to the indented lobe tips, the special appearance of the marginal projections and the thick upper cortex. We have asked for the holotype in PC but it has not arrived. The value of this taxon is therefore still uncertain, e.g. it may turn out to be synonymous with another species in Allocetraria.
Ecology and distribution
Literature:
Randlane, T. & Saag, A. 1993. | Randlane, T. & Saag, A. 2004. | Randlane, T., Saag, A. & Obermayer, W. 2001. | Randlane, T., Saag, A. & Thell, A. 1997. | Thell, A., Randlane, T., Kärnefelt, I., Gao, X. & Saag, A. 1995.
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