Coenogonium fruticulosum
Family
Coenogoniaceae
Flora category
Lichen – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Lichens - Filamentous
Current conservation status
2018 | At Risk – Naturally Uncommon | Qualifiers: DP
Brief description
A filimentous lichen with isidia.
Distribution
North Island: Auckland (Mt Eden, Ardmore), Hawke’s Bay. South Island: Otago, Dunedin.
The specimen from Hawkes Bay (OTA 062514) is very small, and has been identified with some doubt because its isidia are very poorly developed. It was collected in the course of the Department of Conservation TIER1 biodiversity monitoring program.
Habitat
Native lowland forest (on bark), subalpine grassland (on rotting tussock bases), and montane shrubland (on bryophytes and detritus). All known sites have rather low direct light incidence due to shading by vegetation and aspect.
Detailed description
Primary thallus crustose, pale greenish grey, smooth and thin, giving rise to isidia and apothecia, evanescent in densely isidiate parts of the thallus, where only a whitish mesh of hyphae is visible among the isidia. The thallus encrusts the substratum in patches up to 15 cm across, but usually only a few centimetres. Prothallus absent. Isidia densely coralloid, green to orange, up to 1 mm tall, 25–50 µm in diam., of irregular shape, branching dichotomously multiple times, constricted at short intervals, resulting in a granular appearance, often forming a turf that obscures the primary thallus, or aggregated into tiny cushions. Photobiont a green alga; cells round to irregular-ellipsoid, 7–13 µm diam., forming short chains or clumps inside isidia, ?Trentepohlia. Apothecia sessile on primary thallus (not on isidia), constricted at base, usually 0.5–1.5 mm diam., 0.3–0.4 mm high; disc orange (never brown or red), concave to rarely flat or slightly convex; proper exciple smooth to crenulate (but never isidiate), usually paler than disc, ranging from almost concolorous with disc to much paler yellow, paraplectenchymatous in cross section. Hymenium colourless, c. 70–90 µm thick, I+ hemiamyloid reaction of hymenial gel with Lugol’s iodine solution (in water rusty reddish brown, but blue in 10% KOH). Asci cylindrical, c. 60–70 × 4–5 µm, I– (in both water and KOH). Spores 8 per ascus, uniseriate, colourless, ellipsoid, 1-septate (but often with pseudoseptae and appearing 3-septate), (6–)7–10(–11) × 2–3 µm. Paraphyses unbranched, colourless, 1–1.5 µm diam.; apex swollen 3–5 µm diam., apex separated by a septum and a few more septa along cylindrical portion of paraphyses. Subhymenium yellowish. Hypothecium colourless. Pycnidia not seen.
Chemistry: Thallus and apothecia K–, C–, KC–, P–, UV–.
Similar taxa
Separated from other New Zealand Coenogonium species by the isidia.
Substrate
Corticolous, muscicolous, graminicolous
Etymology
fruticulosum: the epithet is a diminutive of Latin fruticosus meaning shrubby or bushy, in reference to the often branched coralloid isidia
Attribution
Fact sheet prepared by Marley Ford (8 August 2022). Information in the Brief description, Distribution, Habitat, Features, and Similar taxa sections copied from Ludwig (2014).
References and further reading
Ludwig L.R. 2014: Coenogonium fruticulosum, a new isidiate species from New Zealand. Australasian Lichenology 75: 18-27.