Cresponea Egea & Torrente
Type : Cresponea premnea (Ach.) Egea & Torrente [Lecidea premnea Ach.]
Description : Thallus crustose, continuous, cracked or occasionally areolate, thin, often poorly developed, endo- to epi-substratal. Surface effuse, whitish, greyish or greenish, sometimes bounded by an irregular black or dark-brown prothalline line. Photobiont green, Trentepohlia. Ascomata apothecia, sessile, constricted at base, 0.2–2.5 mm diam., rounded, scattered or rarely 2–4-together and then slightly contorted through mutual pressure, occasionally with a central column of sterile tissue. Margins lecideine, prominent, raised above disc, smooth, denticulate or crenulate, persistent, glossy, black, epruinose. Disc concave at first, becoming plane to subconvex, black, covered with a ±dense greenish, orange or reddish pruina, often present only in young fruits. Exciple well-developed, without photobiont cells, dark-brown to carbonised, K+ dark-green or olive-brown, of conglutinate, thick-walled hyphae. Hymenium hyaline, I+ blue or reddish, IKI+ blue. Subhymenium (Letrouit-Galinou & Bellemère 1989: 191) pale-brown or rarely colourless. Paraphysoids hyaline, septate, simple or sparsely branched, with little or no anastomosing, up to 2.5 μm thick; apical cells clavate with a distinct pale- to dark-brown external cap, anticlinally arranged or branched-coralloid and forming a granular, dark-brown pseudoepithecium, K+ yellow or rarely purple. Asci bitunicate with fissitunicate dehischence, clavate to cylindrical-clavate, slightly stalked, 8-spored. Exoascus thin and refringent; endoascus variable in thickness, 2-layered, both layers hemiamyloid (IKI+ blue), with an easily distinguished ring structure and a small ocular chamber without an apical nasse (Abietina -type of Egea & Torrente (1994: 20)). Ascospores transversely (3–19)-septate, oblong-fusiform, fusiform to acicular-fusiform, straight to subarcuate, thick-walled, ±widened at septa, surface smooth, without a distinguishable gelatinous sheath, colourless or rarely brownish at maturity. Conidiomata pycnidia, solitary, punctiform, immersed to semi-immersed, epruinose; globose to subglobose, the walls dark-brown or carbonised in outer parts, inner layers colourless to pale-brown. Conidiophores type I or II (Vobis 1980). Conidiogenous cells terminal. Microconidia oblong, straight, short, 3–5 × 1–1.5 μm. Macroconidia unknown.
Chemistry : Thallus K−, C−, KC−, Pd−; TLC−.
Cresponea (honouring the Spanish lichenologist Dr Ana Crespo) was described by Egea & Torrente (1993b) to accommodate a homogeneous group of species formerly included in Lecanactis, and defined by the following characters: lecideine ascomata; epruinose margins; carbonised exciple; paraphysoids not or sparingly branched; asci of Abietina -type; transversely septate, hyaline ascospores (not turning brown at maturity) with a conspicuous endospore; immersed to sub-immersed pycnidia having short, straight microconidia and lacking macroconidia. Species of Cresponea are widely distributed, but the genus is most highly speciose in tropical and subtropical regions. Eleven species are known worldwide (Kirk et al. 2001; Egea et al. 2004b), of which one is recorded from New Zealand. It is accommodated in the family Roccellaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005).
