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Graphis and Allographa (lichenized Ascomycota: Graphidaceae) in Sri Lanka, with six new species and a biogeographical comparison investigating a potential signature of the ‘biotic ferry’ species interchange

Published online by Cambridge University Press:  09 December 2019

Gothamie WEERAKOON*
Affiliation:
Algae, Fungi and Plants Division, Department of Life Sciences, The Natural History Museum, London, SW7 5BD, UK.
André APTROOT
Affiliation:
Laboratório de Botânica / Liquenologia, Instituto de Biociências, Universidade Federal de Mato Grosso do Sul, Avenida Costa e Silva s/n, Bairro Universitário, CEP 79070-900, Campo Grande, Matto Grosso do Sul, Brazil.
Robert LÜCKING
Affiliation:
Science and Education, Integrative Research and Collections (Botany), The Field Museum, 1400 South Lake Shore Drive, Chicago, IL60605, USA; Botanischer Garten und Museum, Königin-Luise Strasse 6-8, 14195Berlin, Germany.
Omal ARACHCHIGE
Affiliation:
Wichita State University, 1845 Fairmount St., Wichita, KS67260, USA.
Siril WIJESUNDARA
Affiliation:
National Institute of Fundamental Studies, Hantanna Road, Kandy, Sri Lanka.
*
G. Weerakoon (corresponding author): Email: gothamiew@yahoo.com

Abstract

We provide an updated survey for Sri Lanka of species of Graphis sensu Staiger, recently divided into Graphis s. str. and Allographa, including brief descriptions and a key to all 124 species currently known. Six new species are described: Allographa bambusicola Weerakoon, Lücking & Aptroot, a bambusicolous Allographa with entire labia, a laterally carbonized excipulum, 80–100 × 15–17 µm large, muriform ascospores and a rather thick, irregularly verrucose lateral thalline margin of the lirellae; A. weerasooriyana Weerakoon, Arachchige & Lücking, a corticolous Allographa resembling A. rustica Kremp. in overall anatomy and chemistry, but with a verrucose thalline margin of the lirellae and labia not distinctly raised above the thalline margin; Graphis flosculifera Weerakoon, Lücking & Aptroot, a corticolous Graphis resembling G. insulana but differing in the unique disposition of the lirellae and the slightly more elongate ascospores; G. rajapakshana Weerakoon, Lücking & Aptroot, a corticolous Graphis resembling G. desquamescens, including in ascospore size, but with lirellae with a distinct lateral thalline margin; G. rimosothallina Weerakoon, Lücking & Aptroot, a corticolous Graphis with a thick, uneven, rimose thallus and Fissurina-like lirellae, a completely carbonized excipulum and transversely 7-septate ascospores, 32–37 × 8–10 µm; and G. thunsinhalayensis Weerakoon, Arachchige & Lücking, a corticolous Graphis resembling G. subalbostriata but with smaller ascospores and lacking white lines between the striae of the labia. We also validate the name G. verrucoserpens Lücking. A total of 106 species are reported here for the first time from Sri Lanka. A biogeographical comparison with two other well-sampled countries (Costa Rica and Thailand) revealed a significantly higher similarity in species composition with Costa Rica than between Thailand and Costa Rica, suggesting a potential signature of the ‘biotic ferry’ hypothesis, that is the migration of lineages from Gondwana (partly corresponding to the modern Neotropics) via the north-eastwards drifting Indian subcontinent and subsequent interchange with Laurasia (partly corresponding to the modern eastern Paleotropics). However, the evolutionary timeline of the clades involved does not support this hypothesis and suggests an alternative explanation of geologically more recent mid- to long-distance dispersal.

Information

Type
Articles
Copyright
Copyright © British Lichen Society 2019
Figure 0

Fig. 1. Comparison of the richness and composition of Graphis and Allographa species from Sri Lanka with Costa Rica and Mexico in the Neotropics and Thailand in the eastern Paleotropics. Numbers in parentheses indicate the total recorded species of Allographa plus Graphis for each country. Increased line thickness reflects greater pairwise Sørensen similarity values for the two countries being compared, with the exact values reported next to each line. In colour online.

Figure 1

Fig. 2. Random subsampling of the species composition of Allographa and Graphis in Thailand and Sri Lanka, with 1000 repeats and subsequent comparison of each repeat to a random subsample of Costa Rica. The resulting Sørensen pairwise similarity values with Costa Rica exhibit significant differences between Thailand and Sri Lanka. The observed central tendency values are indicated for each country. In colour online.

Figure 2

Fig. 3. Habitus and ascospores of Allographa and Graphis species, all holotypes. A & B, A. bambusicola; C, A. weerasooriyana; D–F, G. flosculifera. Scales: A, C, D & E = 1 mm; B & F = 20 µm. In colour online.

Figure 3

Fig. 4. Habitus, ascospores and lirella anatomy of Graphis species, all holotypes. A & B, G. rajapakshana; C & D, G. rimosothallina; E & F, G. thunsinhalayensis. Scales: A, C, D & E = 1 mm; B & F = 20 μm. In colour online.

Figure 4

Fig. 5. Habitus of Graphis verrucoserpens, holotype. Scale = 1 mm. In colour online.