Xanthoparmelia (Vain.) Hale
=CHONDROPSIS Nyl. ex Cromb., 1879, nom. rej.[See Hawksworth & Crespo 2002; Gams 2004]
=NEOFUSCELIA Essl., 1978
=PARAPARMELIA Elix & J.Johnst., 1986
Type : Xanthoparmelia conspersa (Ach.) Hale [=Lichen conspersus Ach.]
Type : Chondropsis semiviridis (F.Muell. ex Nyl.) Nyl. ex Cromb. [=Xanthoparmelia semiviridis (F.Muell. ex Nyl.) O.Blanco, A.Crespo, Elix, D.Hawksw. & Lumbsch (Parmeliopsis semiviridis F.Muell. ex Nyl.)]
Type : Neofuscelia pulla (Ach.) Essl. [=Xanthoparmelia pulla (Ach.) O.Blanco, A.Crespo, Elix, D.Hawksw. & Lumbsch (=Parmelia pulla Ach.)]
Type : Paraparmelia scotophylla (Kurok.) Elix & J.Johnst. [Xanthoparmelia scotophylla (Kurok.) Elix (=Parmelia scotophylla Kurok.)]
Description : Thallus foliose to subcrustose or rarely subfruticose, loosely adnate to very tightly adnate or rarely unattached. Lobes separate to imbricate, weakly concave or flat to strongly convoluted, irregular to linear, irregularly to dichotomously, trichotomously or digitately branched, 0.1–20 mm wide, eciliate, with or without lobules; apices; apices ±incised. Upper surface pale-yellow to yellow-green or grey-green, yellow-grey to grey or grey-green, brown or brownish black, often darkening with age (usnic acid and/or isousnic acid and/or atranorin, ± minor amounts of chloroatranorin), smooth or rugulose, becoming transversely or irregularly cracked, rugose or areolate with age, maculate or not, without pseudocyphellae, rarely pruinose or subgranulate, with or without dactyls, soredia and isidia; lobe margins often black-rimmed; upper cortex consisting of basic palisade plectenchyma or vaulted paraplectenchyma, with pored epicortex. Cell walls containing Xanthoparmelia -type lichenan. Photobiont green, trebouxioid. Medulla loosely packed, white or pigmented. Lower surface flat or canaliculate, smooth to rugose, pale-ivory to yellow, tan-brown or black, rarely pale yellow-green or orange; rhizines sparse to very dense or rarely absent, usually simple, tufted or not, rarely dichotomously or palmately branched. Ascomata apothecia, laminal, sessile to subpedicellate, rarely markedly innate or shortly pedicellate; disc imperforate, concave, often flattening and becoming convex, undulating or distorted with age, red-brown to brown and black. Ascospores ellipsoidal, 8 per ascus, 5.5–14 × 3.5–8 μm. Conidiomata pycnidia, immersed, usually laminal. Conidia bifusiform, 4–9 μm long, rarely weakly fusiform, 4–14 μm long, or bacillar, 4–7 μm long.
Key
Xanthoparmelia, included in the family Parmeliaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005), comprises all the obligately saxicolous and terricolous species of Parmelia s. lat., having small ascospores (6–14 × 4–8 μm), usnic or isousnic acid in the upper cortex, and cell walls containing Xanthoparmelia -type lichenan (Hale 1990; Elix 1993a, 1994s). Further characters are: a lack of pseudocyphellae on the upper surface; mainly simple rhizines; narrow, sublinear, eciliate lobes; short bifusiform (4–9 μm) or rarely bacillar (4–14 μm) conidia; an upper cortex of palisade plectenchyma with a pored epicortex; a diverse medullary secondary chemistry; and a distinctly temperate distribution with major areas of speciation in the Southern Hemisphere (Elix 1993a, 1994s; Elix & Kantvilas 1999a). Recent molecular work (Crespo et al. 2001) has shown that taxa in Xanthoparmelia, Neofuscelia, Paraparmelia and Chondropsis cluster in the same clade, leading Hawksworth & Crespo (2002) to propose conservation of Xanthoparmelia over the older generic name Chondropsis (q.v.). Elix (2003c) subsequently transferred all known species of Paraparmelia to Xanthoparmelia, and recently, Blanco et al. (2004b) transferred all known species of Neofuscelia to Xanthoparmelia.
Hale (1990) published a synopsis of the genus detailing 406 species of Xanthoparmelia worldwide, with major areas of speciation in South Africa (202 species) and Australia (235 species), this astounding species diversity probably arising from rapid morphological and chemical evolution in the many unique, semi-arid habitats present with extensive exposures of granite, sandstone or similar siliceous rocks (Hale 1990; Elix 2004d). Additional taxa in the genus were subsequently recognised in South Africa (Nash & Elix 1987; Brusse 1991a, 1991b, 1993, 1994; Elix 1997a, 1999a, 1999b); Australasia (Elix & Armstrong 1983; Elix 1993b, 1994s, 1995, 1996, 1997b, 1997d, 1999a, 2002b, 2003b, 2004d; Elix & Kantvilas 1999a, 1999b; Elix et al. 2000; Kantvilas et al. 2002); North America (Nash & Elix 2004); South America (Nash et al. 1995; Elix & Nash 1999; Eliasaro & Adler 2002) and Asia (Kurokawa 1989a, 1989b, 1989c; Sharma & Kurokawa 1990).
Neofuscelia (Esslinger 1977b, 1978a), included in the family Parmeliaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005), formerly comprised c. 132 species worldwide (Giordani et al. 2003), all being characterised by: a brown upper cortex giving a blue-green to pale-blue colour with concentrated nitric acid; an absence of pseudocyphellae and soredia; the presence or absence of isidia and maculae; a white medulla; an ivory or black lower surface, generally with simple rhizines; a diverse medullary chemistry; a preference for rock and soil substrata; and a distinctly temperate distribution with the Southern Hemisphere as the major area of speciation, especially South Africa, Australia and New Zealand (Esslinger 1977b, 1986a, 1986b, 2000, 2002b; Brusse 1984, 1991a, 1993, 2003a; Elix 1994k, 1997d, 1999a, 2003a; Kantvilas et al. 2002). The genus is poorly represented in Europe, with only 11 species recorded (Giordani et al. 2003). Esslinger (1978) raised Parmelia subgen. Neofusca (Gyeln.) Essl. to independent generic status on the basis of its unique cortical chemistry, ascospore size, conidial shape and medullary chemistry. Although later studies of cortical morphology using scanning electron microscopy (Lumbsch et al. 1988) confirmed Esslinger's taxonomy, the close relationship of Neofuscelia with Xanthoparmelia was recognised (Elix et al. 1986b) and is supported by recent molecular studies (Crespo & Cubero 1998; Blanco et al. 2004b). Esslinger (2000: 568) pointed out that relationships between Neofuscelia, Paraparmelia and Xanthoparmelia are still very complex and unsettled, and that the HNO3 + blue-green reaction of the upper cortex, used in part to distinguish and define Neofuscelia, is absent in a significant number of taxa from South Africa. Crespo et al. (2001) using molecular techniques showed that Neofuscelia, Xanthoparmelia, Paraparmelia and Chondropsis all nest within the same monophyletic clade, which strongly suggested that taxa in Neofuscelia and Paraparmelia should be transferred to Xanthoparmelia, the necessary transfers being recently effected by Blanco et al. (2004b), a position endorsed here. Although Chondropsis is the oldest name at generic level, to combine all taxa currently placed in the above three genera into Chondropsis would be extremely disruptive, and consequently Hawksworth & Crespo (2002) proposed that Xanthoparmelia be conserved against Chondropsis nom. cons., a procedure agreed to by the Committee for Fungi (Gams 2004).
Elix (2003c: 396) transferred all known taxa in Paraparmelia to Xanthoparmelia and stated therein "The results of a concurrent study on species of Neofuscelia will determine whether or not they too should also be included within Xanthoparmelia. Recent accounts of Neofuscelia (Elix 1993b, 1994k, 1977b, 1977d, 1999a, 2003a; Elix & Polly 1992) in Australasia added further species to the New Zealand mycobiota. Now, in an enlarged Xanthoparmelia, 81 species are recorded from New Zealand (Galloway 1981a, 1985a; Elix et al. 1986b; Elix 1994s; Elix & Kantvilas 1999a; Blanco et al. 2004b).