Knightiellastrum eucalypti (Kantvilas) L. Ludw. & Kantvilas comb. nov.

MycoBank number: MB 833781; Index Fungorum number: IF 833781; Facesoffungi number: FoF 13855;

Knightiella eucalypti (Kantvilas) Kantvilas, Herzogia 31, 567 (2018).—Icmadophila eucalypti Kantvilas, Phytotaxa 18, 72 (2011); type: Australia, Tasmania, Hartz Road near the entrance to the National Park, 43°12S, 146°47E, 570 m, on moist trunks of old Eucalyptus obliqua in mixed forest, 25 July 2007, G. Kantvilas 285/07 (HO—holotypus!; BM!— isotypus).

Thallus squamulose, whitish to pale grey, erhizinate, in section with a pseudocortex 20–30 μm thick comprising randomly orientated, short-celled hyphae 3–5 μm wide, interspersed with occasional dead algal cells; lower surface white, ecorticate. Photobiont a unicellular green alga with globose cells 5–11 μm diam. Ascomata and pycnidia not seen.

Secondary chemistry. Thamnolic acid.

Etymology. From Knightiella and the Latin suffix ‘-astrum’ indicating incomplete resemblance, because the thallus morphology of the type species is reminiscent of a small and infertile individual of Knightiella splachnirima.

Notes. The new genus comprises a single species that occurs on the soft, rotting wood or bark of mature trees in the wet forests of Tasmania. In the absence of reproductive or molecular characters, the initial placement of this lichen in Icmadophila was based entirely on morphological, anatomical, ecological and chemical evidence (Lumbsch et al. 2011). A further character was the occasional occurrence of pinkish gall-like thickenings of unknown origin that resemble apothecial initials of Icmadophilaceae taxa such as Dibaeis and Siphulella. Subsequently, Kantvilas (2018) transferred it to Knightiella, pending supporting molecular data but recognizing that it displayed closer morphological affinities to Knightiella than to Icmadophila. The new molecular data confirm the original family classification of this species, but also highlight that its differences from the other genera are sufficient to warrant generic status. An image of Knightiella eucalypti was published in Kantvilas (2018).