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A synopsis of the genus Arthothelium (Arthoniales) in Tasmania

Published online by Cambridge University Press:  08 December 2021

Gintaras Kantvilas*
Affiliation:
Tasmanian Herbarium, Tasmanian Museum and Art Gallery, P.O. Box 5058, UTAS LPO, Sandy Bay, Tasmania 7005, Australia
*
Author for correspondence: Gintaras Kantvilas. E-mail: Gintaras.Kantvilas@tmag.tas.gov.au

Abstract

The genus Arthothelium A. Massal. in Tasmania comprises ten species. Five of these are described as new: A. bacidinum Kantvilas, a saxicolous, littoral species with subglobose apothecia, non-macrocephalic ascospores, 25−40 × 11−19 μm, and containing the pigment Endoaurantiacum-gold which yields a K+ red reaction; A. insolitum Kantvilas, lichenicolous in rainforest and characterized by subglobose apothecia, very large, non-macrocephalic ascospores, 50−80 × 22−40 μm, and containing the pigment Interveniens-brown which reacts K+ olive green; A. macounioides Kantvilas, corticolous in wet forest and characterized by sessile, convex apothecia, macrocephalic ascospores, 29−42 × 11−18 μm, and containing the pigment Endoaurantiacum-gold; A. magenteum Kantvilas, a common wet forest epiphyte with applanate apothecia, non-macrocephalic ascospores, 25−55 × 11−22 μm, and containing a unique maroon-red, K+ pink pigment; and A. subtectum Kantvilas, a saxicolous species with convex apothecia, macrocephalic ascospores, 22−36 × 9−14 μm, and containing Endoaurantiacum-gold. The New Zealand species A. endoaurantiacum Makhija & Patw. and A. suffusum (C. Knight) Müll. Arg., and the Australian A. velatium Müll. Arg. are recorded for Tasmania for the first time. The names A. obtusulum (Nyl.) Müll. Arg., A. pellucidum (C. Knight) Müll. Arg. and A. polycarpum Müll. Arg. are considered synonyms of the widespread A. ampliatum (C. Knight & Mitten) Müll. Arg. Arthothelium ferax Müll. Arg. is a synonym of A. interveniens (Nyl.) Zahlbr. and A. subspectabile Vĕzda & Kantvilas is a synonym of A. suffusum. The sole record of A. macrothecum (Fée) A. Massal. from Tasmania is found to be based on a misidentification. A key to the species is provided. The importance of apothecial pigments, apothecial morphology and ascospore septation is discussed, and three pigments are characterized by their appearance in water and other standard media.

Information

Type
Standard Paper
Copyright
Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of the British Lichen Society
Figure 0

Table 1. Salient features of Tasmanian species of Arthothelium.

Figure 1

Fig. 1. The Arthothelium-type ascus as exemplified by A. magenteum: young ascus (A), mature ascus (B), with amyloid parts stippled. Scale = 20 μm.

Figure 2

Fig. 2. Ascospores of Tasmanian species of Arthothelium. A, A. ampliatum. B, A. bacidinum. C, A. endoaurantiacum. D, A. insolitum. E, A. interveniens. F, A. macounioides. G, A. magenteum. H, A. subtectum. I, A. suffusum. J, A. velatium. Scale = 10 μm.

Figure 3

Fig. 3. Apothecial pigments in Tasmanian Arthothelium species, in water (left) and 10% KOH (right). A, Endoaurantiacum-gold, illustrated by A. endoaurantiacum and also seen in A. bacidinum, A. macounioides and A. subtectum. B, Magenteum-red, illustrated by A. magenteum. C, Interveniens-brown, illustrated by A. interveniens and also seen in A. ampliatum, A. insolitum, A. suffusum and A. velatium.

Figure 4

Fig. 4. Morphology of Tasmanian species of Arthothelium I. A, A. ampliatum, showing the ‘rubbed down’ apothecial morphology typical of the genus. B, A. bacidinum. C, A. endoaurantiacum. D, A. insolitum, lichenicolous on the grey, squamulose thallus of an unknown lichen. E, A. interveniens. F, A. macounioides. Scales = 1 mm. In colour online.

Figure 5

Fig. 5. Morphology of Tasmanian species of Arthothelium II. A, A. magenteum. B, A. subtectum. C, A. suffusum, with basally constricted, subglobose, pruinose apothecia. D, A. velatium. Scales = 1 mm. In colour online.