Euepixylon is an old name resurrected by Laessøe and Spooner (1994) for a xylariaceous fungus formerly considered to belong to Hypoxylon (Section Papillata, subsection Primo-cinerea) by Miller (1961) and Petrini and Müller (1986), while it was placed in Anthostomella Sacc. by Martin (1976).

 Euepixylon udum shares with Nemania confluens (Tode: Fr.) Laessøe & Spooner, previously a member of the Miller's subsection Primo-cinerea of Hypoxylon and members of Anthostomella a similar stromatal configuration featuring more or less immersed perithecia under a black effused superficial layer (clypeus). In addition, like in most members of Nemania Pouzar and Anthostomella, ascospores of E. udum bear, before being mature, a cellular appendage. Laessøe and Spooner (1994) discussed the affinities of  Euepixylon with these genera. They consider  Euepixylon different from Nemania and Anthostomella in having ascospores with a poroid germ site, different from Nemania in having asci with short stipes and broader than high apical apparatus, and different from Anthostomella in that the clypeoid stromatal layer is not only superficial but extends deeply into the substrate. In addition, Euepixylon is known to have a Geniculosporium-like anamorph (Whalley, 1976) while in Anthostomella anamorphs are refered to Nodulisporium or Virgariella (Martin, 1967; Francis et al., 1980).

The very distinctive poroid germ site of ascospores of E. udum may be encountered in some other taxa: Hypoxylon sphaeriostomum (Schwein.) Sacc., known from U. S. A. (Miller, 1961), has similar stromata and its ascospores, larger than those of E. udum, have a poroid germ site. Thus it was recently accomodated in Euepixylon by Ju and Rogers (2002), under the new combination Euepixylon sphaeriostomum (Schwein.) Ju and Rogers. Laessøe and Spooner (1994) discussed the position of two additional  species which are very closely related and feature ascospores with a poroid germ site: Fuckelia amoena Nitschke and Anthostoma amoenum (Nitschke) Sacc. sensu Hawley. They both differ from E. udum in having a very reduced black outer stromatal layer, replaced by a loose white stroma, and persistent cellular appendages. The position of these both latter taxa remains unclear as they are represented by poor and scanty material.

A description of E. udum and an account of its ecology and distribution in Northern Europe were recently given by Granmo et al. (1999) and Laessøe et al., 2000.