A world key to species of the genera Topelia and Thelopsis (Stictidaceae), with the description of three new species from Brazil and Argentina

The following new corticolous species are described. Thelopsis cruciata Aptroot & M. Caceres, with an olive-green thallus, immersed red-brown perithecia and c. 50-100 cruciate ascospores per ascus, 7-10 x 4-7 mu m, from Brazil. Topelia argentinensis Aptroot, L. I. Ferraro & M. Caceres, with a verrucose, partly almost isidiate, greenish grey thallus, immersed pinkish perithecia and 8 uniseriate muriform ascospores per ascus, 12-17 x 7-11 mu m, from Argentina. Topelia tetraspora Aptroot & M. Caceres, with a c. 0.1-0.6 mu m thick layer of coralloid to usually flattened, irregularly palmately branched isidia c. 0.05 mm diam., ascospores 15-19 x 2-6-septate, muriform, ellipsoid, 39-50 x 11-16 mu m, only up to 4 per ascus maturing, from Brazil. Thelopsis inordinata is reported for the first time from South America, from Guyana. A key is given to all currently known species of Topelia and Thelopsis. The distinction between these genera has become arbitrary with the recent addition of more or less intermediate species.