Fleischer (1923) established the monogeneric Symphyodontaceae and positioned them between the Hookeriaceae and Leucomiaceae. He considered Symphyodon closely related to Chaetomitrium; their leaves are similarly shaped, with short double costae, typically serrate margins, linear, variably prorate cells, and weakly but clearly differentiated, firm-walled alar cells. The presence in Symphyo-don of spinose capsules is its most distinctive feature, and this attribute also occurs in Chaetomitrium. Although Symphyodon has a neckeraceous exostome and that of Chaetomitrium is more typically hypnaceous, in both genera the endostomial cilia are absent or rudimentary. The family was syn-onymized with the Daltoniaceae (Crosby 1974b; Walther 1983; Vitt 1984) based on the erroneous in-terpretation of its peristome as daltoniaceous. It was subsequently recognized again as a monogeneric family and placed in the Leucodontales suborder Neckerineae (Buck & Vitt 1986; He & Snider 2000), Hookeriales (Buck & Ireland 1994), or Hypnales (Buck 1998). The most recent moss ordinal classi-fications (Buck & Goffinet 2000; Goffinet & Buck 2004) have dispensed with the Leucodontales and positioned the Symphyodontaceae in the Hypnales. Buck and Goffinet (2000) placed four genera in the Symphyodontaceae (Chaetomitriopsis, Chaetomitrium, Dimorphocladon, and Symphyodon) and put the family between the Catagoniaceae and Sematophyllaceae. Goffinet and Buck (2004), as well as Goffinet et al. (2009), placed six genera in the family (Chaetomitriopsis, Chaetomitrium, Dimor-phocladon, Symphyodon, Trachythecium, and Unclejackia) and put the Symphyodontaceae between the Rhytidiaceae and Plagiotheciaceae.