Xanthomendoza
Type : Xanthomendoza mendozae (Räsänen) Kondratyuk & Kärnefelt [Xanthoria mendozae Räsänen]
Description : Thallus dorsiventral, foliose to umbilicate, flat and spreading to erect or suberect, yellowish, yellow-grey, yellow-green to orange or reddish orange; with or without soredia; attached to substratum by long whitish or yellowish rhizines. Upper cortex layers paraplectenchymatous, with strongly gelatinised cell walls; the lower cortex similar but in some species of prosoplectenchymatous tissue. Medulla white, solid or of loosely interwoven hyphae. Photobiont green, trebouxioid. Ascomata apothecia, zeorine or lecanorine, sessile; disc concave to plane, yellowish orange to orange reddish; thalline exciple concolorous with thallus, sometimes with small, white, glistening, projecting hairs; proper exciple a prosoplectenchymatous tissue of unorientated hyphae with elongated lumina. Asci clavate, Teloschistes -type (Malcolm & Galloway 1997: 187). Ascospores colourless, ellipsoidal, polarilocular. Conidiomata pycnidia, immersed. Conidia colourless, bacillar, rarely ellipsoidal.
Xanthomendoza comprises c. 20 species worldwide (Kondratyuk & Kärnefelt 1996, 1997; Søchting et al. 2002; Lindblom 2004a) included in the family Teloschistaceae (Eriksson et al. 2004), although further species are known and awaiting description. The genus is widely distributed, being known from Great Britain, Europe, Scandinavia, North and South America, Asia and South Africa, with North America appearing to be the main region of speciation, with 10 species occurring there (Søchting et al. 2002: 236; Lindblom 2004a). The genus is close in terms of both morphology and chemistry to Xanthoria (q.v.) but is distinguished from it by the bacillar conidia and well-developed rhizines with apothecial margins commonly being conspicuously rhizinate. One species occurs in New Zealand. It is possible that the endemic species Xanthoria incavata (Kondratyuk & Galloway 1996) (q.v.) may also belong in Xanthomendoza. Indeed, both of these taxa (X. novozelandica and X. incavata) were recently transferred to the genus Oxneria Kondratyuk & Kärnefelt ndratyuk & Kärnefelt 2003), but as the identity of this newly described genus is still controversial, these two taxa are here maintained in Xanthomendoza and Xanthoria respectively.
