Ascocarps in vertical section subepidermal, developing above fibre bundles in host leaf. Upper wall of dark brown, thick-walled cells, 10-15 µm wide, not varying in width across ascocarp. Hyaline, cylindric cells developing across broken face of upper wall after ascocarp opens, tips of these cells becoming dark brown. Lower wall of dark brown, thick-walled cells, variable in width, more or less obsolete above fibre bundles of host, up to 15 µm wide between fibre bundles.

Paraphyses 2-2.5 µm diam., slightly wider near apex, extending 10-15 µm beyond asci. Asci 100-125 x 4.5-6.5 µm, cylindric or subclavate, tapering to small, rounded apex, wall thickened at apex with broad, central pore, 8-spored. Ascospores 70-85 x 1-1.5 µm. Pycnidia in vertical section mostly subepidermal, lenticular in outline, 25-30 µm high, upper wall of 1-2 layers of thin-walled, pale brown to hyaline cells. Lower wall up to 10 µm wide, of thick-walled, dark brown cells. Conidiogenous cells lining lower wall, 7-10 x 2-3 µm, solitary, flask-shaped, wall thickened and flaring at conidiogenous locus. Conidia cylindric, 0-septate, hyaline, 3-4 x 1 µm.

ETYMOLOGY: hauturuanum; refers to type locality, Hauturu, Maori name for Little Barrier I.

NOTES: L. hauturuanum is easily confused with L. inclusum, the two species often being found together on the, same leaves. L. hauturuanum is distinguished by its narrower, cylindric ascocarps which have a different appearance in vertical section, and by its asci which have a central pore at the apex. L. hauturuanum is similar to L. unciniae but is distinguished by its longer and narrower ascocarps, larger pycnidia, and shorter asci and ascospores.