This is another species in the complex formerly recognized as just a single species, Dictyonema sericeum (Parmasto 1978). It differs from superficially similar species such as D. phyllophilum and D. schenckianum (Müll. Arg.) Zahlbr. (Zahlbruckner 1931: 748) in the very dark color of the thallus and the very broad, dark green rather than bluish green, irregularly arranged fibrils in which the photobiont cells of the cyanobacterial filaments tend to divide longitudinally, giving them partially a 'muriform' appearance. This feature is reminiscent of D. moorei (Nyl.) Henssen (Henssen 1963: 109; Parmasto 1978), in which the hyphal sheath usually contains two filaments, but in D. obscuratum no distinct separate filaments are formed within a single sheath. Also, the surface of the filaments in D. moorei is different and more similar to the genus Acantholichen.
[Lücking et al. 2013].