In this paper, we describe and illustrate a new species, Lindgomyces angustiascus, from submerged wood in lotic and lentic habitats from Florida, North Carolina and Wisconsin, USA. The new species is characterized by black, partially immersed, flattened, globose ascomata; fissitunicate, long, slender, obclavate asci; and one-septate, hyaline, fusiform ascospores with bipolar appendages, each covered with a gelatinous cap. Maximum Likelihood and Bayesian analyses of partial 18S nrDNA and 28S nrDNA, as well as the entire nuclear ribosomal internal transcribed spacer (ITS1, 5.8S and ITS2) region support the placement and establishment of this new species in the Lindgomycetaceae, Pleosporales, Dothideomycetes. Chemical analysis of the organic extract of L. angustiascus revealed the presence of 6E,9E-octadecadienoic acid and ergosterol peroxide as major secondary metabolites.