Flora of New Zealand Series

Type : Thelotrema lepadinum (Ach.) Ach. [=Lichen lepadinus Ach.]

Descriptions : Flora (1985: 571); Hale (1981: 249).

Thelotrema, a genus of c. 100 species (Kirk et al. 2001), of widespread though mainly tropical distribution, is included in the family Thelotremataceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005; Lücking et al. 2004; although Grube et al. (2004a) received no molecular support in their phylogenetic analysis for maintaining the Thelotremataceae as a separate family from the Graphidaceae). Taxonomy of European species was discussed in Salisbury (1972a, 1972b, 1975, 1978) and Purvis et al. (1995), and tropical species by Hale (1972, 1974a, 1974b, 1978a, 1978b, 1980, 1981). Indian species were treated by Patwardhan et al. (1977a, 1977b, 1985) and Japanese taxa were revised by Matsumoto (2000). Four new species were recently described from SE Asia (Homchantara & Coppins 2002). Thelotrema is characterised by the constant presence of periphysoids and the frequent occurrence of a free (detached) exciple (Salisbury 1972a; Hale 1980, 1981; Hawksworth 1992c; Matsumoto 2000). Pycnidia are Umbilicaria -type, having type-V (Vobis 1980) conidiophores, and oblong conidia (Matsumoto & Deguchi 1999). In the most recent regional revision, Matsumoto (2000: 16) divides Thelotrema into two sections: (1) sect. Asteristion (Leight.) Matsumoto – thalline exciple recurved, exciple fused with thalline exciple, and (2) sect. Thelotrema – thalline exciple incurved, exciple free from thalline exciple. A revision of Australian taxa is currently in progress, using molecular techniques to circumscribe monophyletic groups within the family (Lumbsch et al. 2004a). Recent molecular work has shown that Thelotremataceae (+ Graphidaceae) form a strongly supported clade, sister to Coenogoniaceae and Gyalectaceae in a broadly conceived Ostropales (Lumbsch et al. 2004a).

Species of Thelotrema are common and widespread in New Zealand, but the genus has still not been carefully collected and studied here and a detailed treatment of it is long overdue. Nine species are recorded here. Two species formerly included in Thelotrema, viz. T. decorticans and T. subdenticulatum, are now referred to Topeliopsis (Frisch & Kalb 2006) (q.v.).