Anamorph: conidiomatal locules 0.75-1 x 1-1.5 mm, formed within the stromata, often multilocular, convoluted and radiating from the centre, probably preceeding perithecial formation. Conidiophores 8-15 (-32) µm long, hyaline, septate, branched irregularly at the base and above, formed from the inner cells of the locule walls. Conidiogenous cells not clearly distinct morphologically from the conidiophores, usually formed as long distinct branches, straight, hyaline, smooth, proliferating percurrently, collarette and periclinal thickening inconspicuous. Conidia (2-) 3-5 (-8) x 1 (-2) µm, cylindrical to allantoid, hyaline, thin-walled, aseptate, without guttules, often extruded as globose droplets or tendrils.
Teleomorph: stromata 1-2 mm diam., the exposed part flat to conical, prominent, often erumpent through a stellate fissure, containing (3-) 5-8 (-15) ascomata. Ectostromatic disc 500-700 µm diam., white to pale brownish, sometimes obliterated by the emerging perithecial necks. Entostroma white to greyish, composed of interwoven hyphae with some host cells intermixed in the lower part, well-developed, delimited by a conspicuous black stromatic zone line 20-90 µm thick that is conspicuous ventrally. Ascomata perithecia, 300-500 µm diam., ± globose with necks 300-420 µm long, apically rounded and sometimes very broad; black, upright to oblique, necks converging, emergent through the disc but only just exceeding the upper surface. Peridium 30-50 µm thick, composed of dark, thick-walled angular cells. Interascal tissue composed of paraphyses, 6-9 µm diam., elongate, thin-walled, septate, quite numerous, the neck periphysate. Asci (47-) 58-62 (-84) x (6-) 7-8 (-10) µm, cylindrical-clavate with a tapering base, apically thickened, with a refractive I- apical ring, becoming detached within the perithecial cavity, probably mostly 8-spored. Ascospores (7-) 12-14 (-21) x (1.5-) 2.5-3 (-4) µm, allantoid to cylindrical, hyaline, aseptate, smooth- and thin-walled, without a gelatinous sheath or appendages.
Not formally evaluated. The species is widespread and may well be under-recorded. It was suggested that the species is non-native (Roy et al. 2012), but the evidence for this position was not made clear; presumably that judgement was based on the status of its principal host.
This appears to be the only species of Leucostoma to possess interascal tissues, which could support the phylogenetic hypothesis that this is a basal member of the genus. However, paraphyses are greatly under-recorded within the Diaporthales as they are usually very thin-walled and evanescent prior to maturity of the asci, and they may have been missed in other species.
Leucostoma kunzei is also found on Larix, but that species has substantially smaller ascospores compared with those of L. curreyi.
This species may occupy a basal clade within Leucostoma, but bootstrap values in the research to date were low. More samples and a multigene approach would be useful.
Associated with conifers; most reports are on Larix decidua, but there are a few records on Cedrus, Picea and Pinus.
Scattered throughout England and Scotland, with a distribution extending from Cornwall to Moray.
Considered to cause canker of twigs and branches, possibly establishing as a wound parasite or an invader of stressed trees.