Apothecia scattered, stipitate, up to 1 mm high; disc pure white, up to 1.6 mm in diam when fresh, Greyish Red (7B6) when dry, with elevated, incurving margin; receptacle white when fresh, buff white when dry; stipe stout, shearing 1/2-2/3 of the height, composed of elongate cells, 15-25 x 3.5-5 µm. Ectal excipuium two layered; outer layer "textura prismatica" of thick-walled, agglutinated prismatic cells, 19.5-34 x 4.5-9 µm; inner layer thin-walled, non-agglutinated hyphae of 1.5-2 µm, wide, running parallel to the outside, poorly developed near the margin. Medullary excipulum 'textura intricata', of vertically developing hyphae arising from inner ectal excipulum. Hairs cylindrical, thin-walled, multi-septate, granulate all over, up to 150 µm long, 3-3.5 µm wide. Asci 89-95 x 6-7 µm, uniform in shape, cylindrical clavate, thick-walled, arising from simple septa; apex conical with flattened top, MLZ+ without KOH pretreatment. Ascospores 60-74 x 1.5 µm, filiform, flexuous, borne in one fascicles in the asci, non-septate, very rarely (about one out of 50) septate; septation irregular, 2- to 3-septate near the end. Paraphyses narrowly lanceotate to cylindrical with pointed apex, straight, 2-3 µm wide at the widest point, septate, not exceeding the asci.
Colonies on PDA 1 5-18 mm in diam (23C, 3 wk), low and dense, plane, funiculous, smooth at the margin, slimy, Light Yellow (4A4) to Brownish Orange (5C3); reverse concolorous. Context tough and glutinous. Aerial mycelium little to not developed, forming fascicles. Sectors and zonations absent. Margin distinct, entire, superficial or immersed.
Notes. There is another species of Lachnum on Livistona leaves with filiform ascospores: L. pritzelianum (Henn.) Spooner. Lachnum palmae has agglutinated tissue in the ectal excipulum. This is a remarkable characteristic in the genus Lachnum, which distinguishes L. palmae from L. pritzelianum. Nagao (1996a) collected L. pritzelianum from the same substrate in Bonin Isl.