Bacidia De Not.
=PSORELLA Müll.Arg., 1894
Type : Bacidia rosella (Pers.) De Not. [=Lichen rosellus Pers.]
Type : Psorella pannaroidea (C.Knight) Müll.Arg. [=Bacidia pannaroidea C.Knight (=B. wellingtonii (Stirt.) D.J.Galloway).]
Description : Flora (1985: 25). See also Ekman (1996a: 60–61).
Key
Bacidia is a widespread genus of c. 50–100 species (Ekman 2004a) of which two are lichenicolous (Ekman 1996a). It is included in the family Ramalinaceae (Ekman (2001: 783–784, 791–796; 2004a; Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005). Ekman (1996a: 36) defines Bacidia by the following characters: (1) Lichenised with green chlorococcoid algae. (2) Thallus crustose, never dissolving into goniocysts; upper cortex of two layers, the upper layer an epinecral layer with crystals. (3) Biatorine or lecideine apothecia. (4) Proper exciple well-developed, hyphae distinctly radiating, ±abundantly furcate but sparingly or not anastomosing. (5) Hypothecium not chondroid, of distinctly different texture to, and distinctly delimited from, proper exciple. (6) Paraphyses simple to sparsely branching in upper parts, sparingly anastomosing, without a thick gelatinous wall in upper parts. (7) Hymenium and subhymenium I+ blue, often distinctly pigmented in upper parts. (8) Apical tholus of ascus with a narrow c-layer, with a high, blunt or pointed axial body, the width of which is one-third or less of the entire d-layer, and a high or low, blunt or pointed ocular chamber (Malcolm & Galloway 1997: 186). (9) Ascospores acicular, clavate, bacillar or fusiform, at maturity with 3 or more transverse septa; colourless, thick-walled, without a perispore or ornamentation. (10) Pycnidia with cylindrical conidiogenous cells, producing conidia terminally. Conidia filiform and curved. (11) A simple secondary chemistry of atranorin, rarely zeorin or 4- O -methylcryptochlorophaeic acid or unidentified orcinol meta- depsides.
In the 19th century, Charles Knight made a study of Bacidia (Knight 1880) publishing 19 new names in the genus, many of which were placed in synonymy with existing taxa (Galloway 1985a: 25–36). Taxa recorded in Bacidia in the Flora (Galloway 1985a) are now accommodated in several other genera including Bacidina, Bapalmuia, Bilimbia, Byssoloma and Sarrameana (q.v.). As before, the present account (16 taxa are discussed here) is not a critical revision, but rather a preliminary evaluation of available type specimens with some ordering of obvious synonyms. Taxa with ellipsoidal and with acicular ascospores are present, so the genus as circumscribed in this account is undoubtedly heterogeneous. In New Zealand Bacidia appears to be well-developed in humid, relatively undisturbed, lowland forest habitats where species are found on bark (mainly) and rocks. One species is known from high-alpine calciferous soil, and one species is lichenicolous. It is urgently in need of increased collection and critical study here.
