Flora of New Zealand Series

Type : Lecidea fuscoatra (L.) Ach. [=Lichen fusco-ater L.]

Description : Thallus crustose to rarely squamulose, superficial or poorly developed (cryptothalline) or immersed, continuous to cracked or areolate, generally grey or grey-white, sometimes chalky-white, greenish or brown-pigmented ("atrobrunnea"-group), sometimes distinctly rusty-red-oxydated when growing on iron-rich substrata, surface dull or glossy; prothallus present or absent. Photobiont green, Trebouxia and related genera. Cephalodia unknown. Without isidia or soredia. Ascomata apothecia, immersed to sessile, generally persistently marginate, disc black, rarely dark-brown, sometimes blue-grey-pruinose. Thalline exciple absent. Proper exciple of irregular chains of swollen cells, outer layer brown to dark-brown, internal layers hyaline. Epithecium pigmented, olive, bright-green, bluish green, pale- to dark-brown, green-black to black. Hymenium hyaline or faintly greenish, I+ blue, 30–90 μm tall. Hypothecium colourless to brown or black. Hamathecium of simple or sparsely branched, little anastomosed paraphyses, the apices usually swollen and pigmented. Asci elongate–clavate, 8-spored, Lecidea -type (Rambold 1989: 22, fig. 2F; Malcolm & Galloway 1997: 186), outer coat I+ blue, apex thickened, apical dome I+ pale-blue, usually with a distinct I+blue, meniscus-like, shallow subapical ring. Ascospores small (rarely larger than 17 × 8 μm), ellipsoidal or oblong to subglobose, usually with a central plasma bridge ("pseudodiblastic"), simple, smooth, colourless without a perispore. Conidiomata pycnidia, immersed, flask-shaped or cerebriform, blackish, at least at ostiole. Conidia formed apically, elongate–bacillar, simple, colourless. Secondary metabolites usually of para-depsides of orcinol-type, and depsidones of β-orcinol-type (xanthones, usnic acids, anthraquinones, pulvinic acid derivatives and triterpenoids unknown). Species of Lecidea s. str. are almost exclusively saxicolous on acid rocks, with a few able to colonise calcareous rocks, but only exceptionally on pure limestone. A few taxa can colonise rocky debris, sandy soil or clay and, very exceptionally, hard, dust-impregnated, decorticated wood.

Lecidea, in the delimitation of Hertel (1995, see above), was divided into three subgeneric units by Rambold (1989) viz., (1) Lecidea subgen. Lecidea, comprising usually non-alpine, mostly thermophilous species with relatively short conidia and (when fresh) an I+ red to brown hymenium; (2) Lecidea subgen. Rehmiopsis (Müll.Arg.) Rambold & Pietschmann [Type: Patellaria heterodoxa Müll.Arg. (=Lecidea lapicida (Ach.) Ach.)]. This subgenus comprises more or less alpine species with relatively long conidia and an I+ blue to blue-brown hymenium; (3) Lecidea subg. Cladopycnidium (H.Magn.) Hertel Rambold & Pietschmann [Type: Cladopycnidium sinense H.Magn. (=Lecidea tessellata Flörke)]. This subgenus is defined by an I+ bluish hymenium, cylindrical conidia, and thick spore walls (up to 1.5 μm). It comprises the widespread species L. tessellata Flörke, which usually occurs in alpine habitats.

The account of Lecidea in the Flora (Galloway 1985a: 220–241) was prepared just at the time of the active dismemberment of Lecidea  sensu Zahlbr., but before publication of two important papers (Hafellner 1984; Hertel 1984b) that signalled a much more restricted and natural concept of Lecidea. The Flora account is therefore much in need of revision and comprises taxa now included in several other genera including: Cliostomum, Lecanora, Lecidella, Micarea, Miltidea, Paraporpidia, Placynthiella, Poeltiaria, Porpidia, Pyrrhospora, Ramboldia, Rhizolechia, Rimularia, Sarrameana, Trapeliopsis and Tylothallia (q.v.). Hannes Hertel, the leading contemporary student of Lecidea, has collected Lecideaceae s. lat., from many habitats in New Zealand, from coastal rocks to high-alpine barrens, and it is largely due to his careful work on the genus (and the family), and his extensive field and herbarium experience, that we owe our present understanding of Lecidea (Hertel 1967, 1968, 1970c, 1971a, 1971b, 1975a, 1975b, 1975c, 1977a, 1977b, 1977c, 1981, 1984a, 1984b, 1985b, 1987b, 1989b, 1991,1992b, 1995, 1997, 2001; Leuckert & Hertel 2003; Hertel & Andreev 2003). Rambold's (1989) monograph on saxicolous lecideoid lichens in Australia is also an extremely valuable source of information for species occurring in New Zealand. A recent molecular study on Porpidia and allied taxa (Buschbom & Mueller 2004) has shown that Lecidea is one of the nested subgroups within Porpidia s. lat.

The present account records 29 taxa in 26 species, but is recognised as still containing heterogeneous elements, especially corticolous species that will eventually be placed elsewhere. Lecidea, in its present circumscription, is included in the family Lecideaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005), and comprises c. 100 species (Hertel & Printzen 2004) with apparently two areas of diversity (1): semi-arid non-alpine regions colonised mainly by species of subgen. Lecidea, and (2): humid and cool–temperate regions colonised mainly by species from subgen. Rehmiopsis (Rambold 1989; Hertel 1997). Within Lecidea s. str., in New Zealand, the following informal groups are present: (1) Rusty-oxydated thallus: L. diducens, L. lapicida var. lapicida, L. lapicida var. pantherina, L. lygomma, L. lygomma var. crassilabra; (2) Yellow-brown to red-brown, areolate thallus, thallus glossy (unpigmented epinecral cortex layer) "atrobrunneoid" group: L. atromorio, L. capensis, L. fuscoatrula; (3) Cryptothalline species: L. diducens, L. lygomma var. crassilabra, L. sarcogynoides, L. tararuensis.

The species L. aucklandica, L. canorufescens, L. cerinocarpa, L. coccodes, L. conisalea, L. dacrydii, L. dracophylli, L. endochlora, L. fuscocincta, L. miscescens, L. nigratula, L. senescens, L. spheniscidarum, L. subsericea, L. swartzioidea, and L. thomsonii do not belong in Lecidea s. str., and will need to be placed elsewhere, the corticolous species possibly or probably within Biatora (q.v.). However, more work is needed on these corticolous taxa before a suitable solution is found to their correct generic affiliations. They are meanwhile here maintained in Lecidea s. lat.