Porina Ach.
Thallus crustose, heteromerous, well-developed on substratum to effuse, ecorticate. Photobiont green, Trentepohlia or Phycopeltis. Perithecia compound, comprising an involucrellum and exciple, sessile to immersed, glabrous, sometimes subtomentose, rarely ± verrucose. Paraphyses persistent, discrete, simple or rarely branched, c. 1-2 µm thick. Asci unitunicate, clavate-fusiform, ± ellipsoid, obclavate or cylindrical, thin-walled (wall 1-2 µm thick), 8-spored. Ascospores colourless, elongate-fusiform, with one to several transverse septa, septa thin, locules ± cylindrical. Pycnidia sessile to immersed. Macroconidia simple, or transversely septate, filiform, cylindrical or bacillar. Microconidia simple, usually ellipsoid or fusiform.
Key
Porina is a genus of c. 300 species of pyrenocarpous lichens in the family Clathroporinaceae, most taxa occuring in tropical regions. Corticolous, saxicolous and foliicolous taxa occur in New Zealand although the genus is still very poorly collected and understood here. In this account 16 species are discussed. Useful nomenclatural, morphological, anatomical and distributional data are found in Santesson [ Symb. bot. upsal. 12: 199-266 (1952)], and in Swinscow [ Lichenologist 2: 6-56 (1962)]. Authentic material of the taxa P. retrospiciens (Stirton) Müll. Arg., and P. cinereonigrescens (Stirton) Müll. Arg., was not found either in BM, GLAM or WELT, the usual repositories of John Buchanan's New Zealand lichens named by James Stirton.