Flora of New Zealand Series

≡ *Microthelia cargilliana Linds., Trans. Roy. Soc. Edin. 24: 439 (1866).

=*Coniothyrium ramalinae Vouaux, Bull. Trimest. Soc. Mycol. Fr. 30: 296 (1914).

Holotype: New Zealand. Otago, Saddlehill Bush, parasitic on Parmelia perforata [=Parmotrema reticulatum] on trunks of trees, 5.x.1861, W.L. Lindsay – E.

Description : Lichenicolous, on apothecia and thallus of host lichens. Pycnidia scattered, immersed except near apex or below and becoming erumpent, subglobose to almost cupuliform, black, 100–175(–200) μm diam., opening by an irregular pore or slit and sometimes becoming expanded. Pycnidia wall 7–10 μm thick, of 2–4 layers of pseudoparenchymatous cells; cells polyhedral to rounded, the outer layers thick-walled and dark-brown, the inner layers thin-walled and pale-brown to subhyaline, mainly 4–10 μm diam. Conidiogenous cells lining inner wall of pycnidial cavity, phialidic or rarely annellide-like with 1 annellation, subcylindrical to ampulliform below, mainly hyaline but sometimes slightly pigmented and verruculose apically, (7–)8–10(–12) × (2.5–)3–3.5 μm Conidia arising singly from the apices of conidiogenous cells, rather irregularly subglobose to almost pyriform, distinctly truncate at base, dark-brown but appearing almost black in mass, often with a single large guttule, walls very coarsely verruculose, 5–7(–7.5) × 3.5–5(–6) μm.

S: Otago (Dunedin). Known also from Great Britain, France, the United States (Florida) and Mexico (Hawksworth 1977b, 1981, 2003; Etayo & Diederich 1996; Diederich 2003; Cole & Hawksworth 2004).

?Cosmopolitan

Hosts : On apothecia of Parmotrema reticulata, and apothecia and thallus of Ramalina celastri and Usnea (the latter two species in Mexico), and on Platismatia (in the French Pyrenees).

Illustrations : Lindsay (1866c: pl. XXX, figs 31–34 – as Microthelia cargilliana); Hawksworth (1976: 55, fig. 3A, B; 1977b: fig. 1D; pl. 25E–G; 1981: 34, fig. 18C).

* Lichenoconium cargillianum is characterised by: the lichenicolous habit (on Parmotrema reticulatum as host); the large pycnidia (100–200 μm diam.); and by the coarsely verrucose, subglobose and comparatively large conidia, 5–7(–7.5) × 3.5–5(–6) μm. Lauder Lindsay wrote of this species "In site and general characters, this species resembles M. perrugosaria [=Polycoccum squamarioides q.v.], from which, however, it differs in the characters of its spores; the upper half seated on the epithecium, generally of old deformed apothecia, the lower immersed in its tissues; generally isolated or discrete; scattered in considerable numbers on a single apothecium (fig. 31). Like those of M. perrugosaria, they have externally the characters of a minute Verrucaria. No thecae were seen but the perithecia contained abundance of brown, round spores, about .00015" to .00025"; simple or with double contour (fig. 34). The beautiful blue reaction with iodine on the thecae and hymenial gelatine of the Parmelia further sufficiently distinguish it from the hymenium of the parasite. Nor can the Microthelia be confounded with the parasitic Abrothallus Curreyi, which affects the thallus of the same Parmelia, and which may in some of its conditions or parts be mistaken for the spermogones of the Parmelia. The Abrothallus is distinguished as a Lichen by the blue reaction of its thecae and hymenial gelatine with tincture of iodine, and by the presence of distinct paraphyses with very granular and dark brown tuberculated heads, as well as by its general analogies … M. Cargillianum, whose name is in honour of my friend John Cargill, F.R.G.S., of Greenisland [sic], Member of the Legislative Assembly of New Zealand, and one of the best known pioneer settlers of Otago, to whom I was indebted for many acts of kindess in the course of my Otago excursions" (Lindsay 1866c: 440).