Leptorhaphis confertior (All Fungi)
Thallus: smooth, continuous, not well delimited; immersed in the substratum, composed of colourless to pale brown smooth thin-walled hyphae ca 4 µm diam, associated with trentepohlioid algae with filaments 8.5-15.5 µm diam.
Anamorph: reported in the literature, but not seen in GB&I material.
Teleomorph: ascomata 140-200 µm diam, blackish, shiny, smooth, usually confluent in groups of 3-5, circular, not surrounded by a basal fringe; at first immersed in the substratum, becoming half immersed to superficial, hemispherical, ca 85 µm high, dimidiate; the ostiole centrally located in a small depression. Involucrellum reddish-brown to black, ca 20-30 µm thick, not extending beyond the ascomata, consisting of bark cells intermixed with reddish to dark brown, nearly black, thin-walled smooth isodiametric cells 3-4.5 µm diam. Exciple intergrading with the involucrellum, colourless to pale brown, 7.5-12 µm thick, consisting of smooth thin-walled isodiametric cells, forming a textura globulosa-angularis. Interascal tissue of pseudoparaphyses 1.5-2 µm diam, staining bluish-green in iodine. Asci 50-60 x 9-14 µm, cylindric-clavate, short-stalked, fissitunicate, the apex of the inner wall truncate to slightly pointed, 8-spored. Ascospores fasciculate in the ascus, 15-20 (-25) x 1.5-2 µm, colourless, 0- or 1-septate, fusiform, attenuated at the apices, without a gelatinous sheath or appendages.
Not formally assessed, but potentially Critically Endangered. The species has been recorded once recently from Skye, the first time that it has been collected since the original description which was based on a collection from Norway in the late nineteenth century. Its habitat in Atlantic hazel woodland has been extensively surveyed in recent years, suggesting that the species is rare rather than overlooked, although it could be mistaken for an Arthonia-like lichen based on external examination only. The land on which it was discovered has statutory protection, and steps are being taken to rehabilitate the habitat which could improve its prospects for survival. It was found only on one mature tree, and not re-found during a short second survey. This could possibly be for reasons of seasonality, as its ascomata may be ephemeral in appearance.
Leptorhaphis confertior was considered to be a synonym of L. deformis by Aguirre-Hudson (1991), but until now both taxa were known only from single collections, and the lack of an evident external thallus and the ascomata developing in groups, combined with development on Ilex rather than Salix, suggests that they may be distinct.
Possibly lichenized with trentepohlioid lichens, on/in bark of Ilex aquifolium.
In GB&I, only reported from Skye (Scotland).