Thallus thick, of convex irregular verrucae, dull dark brown; hypothallus lacking. Apothecia to 1 mm, borne on the verrucae; margin of same color as thallus, sometimes undeveloped, revealing proper margin, or entire, flexuous and persistent; exciple hyaline or brown; disk black, flat; hypothecium hyaline to dark brown; epihymenium dark brown; hymenium 60-80 μm, hyaline; paraphyses 2-2.5 μm, tips 5-6 μm and heavily pigmented; asci clavate; spores with swellings to each side of porus, Buellia-type, septum prominent, 10-15 x 6-8.3 μm.

This species grows on siliceous rocks, sometimes on other lichens. It is known from northern Europe and rarely in the American Arctic.

Thallus thick, dark brown, usually discontinuous, consisting of tumid, irregular Verrucae, matt.  Thallus indeterminate, without perceptible hypothallus.  Apothecia frequent, typically contiguous, broadly attached or sessile, born at all angles on the verrucae, to 0.60-1.00 mm diam., disc black, more or less persistently plane; thalline margin concolorous with thallus, 0.05-0.10 mm wide, sometimes undeveloped or incomplete revealing proper margin, or entire, flexuose and persistent.

Amphithecium 55-90 µm wide laterally; cortex 5-10 µm wide laterally, sometimes with epicortex ca. 5 µm wide; 80-120 µm below, cortex ca. 10 µm wide.  Peripheral cortical cells pigmented, to 5.0-6.5 µm wide; algal cells to 11.5-24.0 µm diam.  Parathecium, hyaline or pigmented a shade of brown, 5-15 µm wide laterally, 20-40 µm wide above.  Hypothecium hyaline to dark brown, 30-60 µm deep, sometimes extending into the medulla as a pigmented stipe.  Hymenium 60-80 µm high, paraphyses 1.5-2.5 µm wide, apices expanded to 5.0-7.0 µm wide, heavily pigmented forming a dark brown epihymenium.  Asci Bacidia-tye, (33-40) X (14-17) µm; spores Beltraminia-(including Buellia-) type, 11.0-(13.1-13.7)-15.9, 13.4 X 6.9, 5.5-(6.7-7.1)-8.4 µm, locules filling cells, torus absent at all stages of development, walls ornamented (x1250).  Conidiomata immersed, ostiole dark brown to black, Conidiophores Type III (according to Vobis 1980); conidia filiform and arcuate 13.0-17.0 x 1.0 µm Chemistry.  Thalline reactions negative, no substances detected by TLC (see also Hecklau et al. 1981).

Ecology and distribution.  Recorded on siliceous rocks, frequently on large boulders, particularly bird perches.  Distributed across the northern hemisphere in northern regions (Figure 1).  The species was first reported from North America by Thomson (1979) from Alaska but this material is a Buellia (Sect. Melanaspicilia) species.  However, the record of Rinodina milvina is based on a specimen of A. cacuminum.

Discussion

Amandinea cacuminum is a rather distinctive species characterized by the dark brown fragmented thallus consisting of tumid verrucae with erratically inserted apothecia.  The spores have been compared by Degelius (1939) to those of Rinodina pyrina but the spores of this species possess septal wall thickenings during early developmental stages which are lacking in A. cacuminum.

The discovery of a pigmented hypothecium in a number of specimens, the filiform conidia and the fact that the thalline margin is frequently incomplete suggests that the species belongs in Amandinea rather than Rinodina where it has previously been placed.  One specimen, Scotter 33154 (WIS), has relatively few lecanorine apothecia and intergrades continuously with adjacent lecideine apothecia when they become indistinguishable from those of A. punctata (Hoffm.)  Coppins & Scheidegger, except for thallus morphology and colour.

Ascal and molecular data confirm the need to transfer Rinodina cacuminum to Amandinea.  Ramold et al. (1994) found the species to possess Bacidia-type asci characteristic of Amandinea species rather than Lecanora-type asci which define the genus Rinodina.  Preliminary molecular results (Gert Helms, Gottingen, personal communication) also aligns the species with Amandinea rather than Rinodina.