Sticta (Schreb.) Ach.
Type : Sticta sylvatica (Huds.) Ach. [=Lichen sylvaticus Huds.]
Description : Thallus foliose, heteromerous, dorsiventral, lobate, irregularly spreading, ±loosely attached or appearing ±unattached, or attached by a root-like holdfast, developing a distinctive, erect, ±terete stalk from which develop monophyllous to polyphyllous lobes, 2–10(–15) cm diam. Lobes irregularly branching, rounded to imbricate to variously incised, often lacerate-notched, with or without isidia, phyllidia or soredia, tough, coriaceous to fragile, thin to thick. Upper surface smooth, wrinkled or obscurely ridged, sometimes shallowly pitted or faveolate, glossy or matt, with or without isidia, maculae, phyllidia or soredia. Medulla white. Photobiont green or cyanobacterial (in taxa with green primary photobionts, cyanobacteria are also present in internal cephalodia). Lower surface pale or dark, glabrous or tomentose, cyphellae always present. Cyphellae round to irregular, with a well-defined, often raised margin, the floor of the cyphellae bounded by a membrane and not of projecting medullary hyphae (as in Pseudocyphellaria), membrane white, orange or pinkish yellow. Ascomata apothecia, often rather sparsely developed, hemiangiocarpic, laminal, rarely marginal, sessile or pedicellate, margins entire or crenate; disc matt or glossy, not pruinose; exciple well-developed, paler than disc, lacking photobiont cells, smooth or verrucose-scabrid. Hymenium hyaline to pale straw-yellow, 70–150 μm tall, I+ blue; hamathecium of simple, septate, filiform paraphyses, swollen and sometimes pigmented at apices; hypothecium opaque, of densely interwoven hyphae, pale to dark yellow-brown or red-brown. Asci shorter than paraphyses, cylindrical to clavate. Ascospores 8 per ascus, colourless or brown, fusiform-ellipsoidal to broadly ellipsoidal, generally 1–3-septate, rarely 5–7-septate. Conidiomata pycnidia, immersed, punctate to subglobose (Lobaria -type as in Pseudocyphellaria). Conidia colourless, short, bacillar to sublageniform, borne laterally and terminally on simple to slightly branched conidiophores.
Chemistry : No acetone-soluble compounds detected by TLC. Species of Sticta have a range of water-soluble, simple monosaccharides such as sugars and polyhydric alcohols, especially mannitol and D-arabinitol. Methylamines give a number of species (especially those with cyanobacterial photobionts) a distinctive, fishy smell.
Key
Species of Sticta are large, conspicuous, foliose lichens characterised by a ±tomentose lower surface with cyphellae (Yoshimura & Hurutani 1987) as constantly occurring structures, a distinctive and readily observed character that readily distinguishes this genus from Lobaria and Pseudocyphellaria with which it was often confused in the past. It is included in the family Lobariaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005) with c. 105 species known worldwide, though this is probably a considerable underestimate (Galloway & Thomas 2004). For a concise introduction to the genus, its morphology, anatomy and biology see Galloway (1994c). Additional studies on the genus include Galloway (1994b, 1995a, 1997, 1998e, 2001f), McDonald et al. (2003) and Galloway & Thomas (2004). Fourteen species are known from New Zealand. Several species are parasitised by the lichenicolous fungus * Plectocarpon (Ertz et al. 2005).
