Bactrospora brodoi

The thallus of B. brodoi forms a very thin, whitish film that is mostly immersed in the outer bark (endophloeodal), lacking a distinct cortex or medulla. The photobiont is Trentepohlia. In section it is to about 50 micrometres (μm) thick and shows positive iodine reactions (I+; K/I+). The black fruiting bodies (apothecia) are scattered, roundish to slightly irregular, flat to gently convex, without a frosty coating (epruinose) and lacking a raised rim (immarginate), typically 0.3–0.7 mm in diameter. The excipulum—the dark rim tissue around the disc—is thin and open beneath, measuring up to about 25–30 μm at the top and 25–40 (up to 70) μm at the base. The hymenium is 80–125 μm tall and overlies a pale to dark-brown subhymenium 125–250 (up to 300) μm thick. Paraphysoid tips branch and interconnect to form a loose reticulum. Asci are slender, measuring 70–90 × 14–16 μm, and contain narrow, many-celled ascospores of the patellarioides-type, (44–)55–75 × (3–)3.5–4 μm, with (10–)14–24 cross-walls (septa) and typically tapered at one end; in practical terms they look like very fine threads divided into many tiny cells. Pycnidia (asexual structures) are immersed and roughly spherical (globose, and produce straight to slightly curved conidia 7–11 × 1 μm. No lichen products were detected by standard chemical tests. Two pycnidial morphs occur. …

In Canada the species is confirmed from the type locality in New Brunswick, where it grew on the bark of a mature yellow birch on a steep, slightly to moderately shaded, south-facing slope in mixed red spruce–birch forest; historical Newfoundland material comes from Coal River. Additional Canadian records include further sites in New Brunswick and a record from Prince Edward Island. Elsewhere in eastern Canada the species occupies the basal few metres of medium- to large-diameter trunks of Thuja occidentalis in old, swampy stands near streams or rivers; in these sites it usually occurs on only one or a few trees, but can cover several square decimetres on favourable trunks. Associated taxa on yellow birch sites include Calicium viride, Chaenothecopsis savonica, Cliostomum griffithii, Opegrapha niveoatra, O. varia, and Variolaria amara; in Thuja swamps the pin lichen Chaenotheca laevigata is frequent. It has also been recorded from California's Santa Rosa Island, where it was growing on Heteromeles arbutifolia. Material from Santa Rosa Island matches B. brodoi morphologically but occurs in a contrasting ecology; its status remains uncertain pending molecular data, and some north-western records have proved to be B. …