Rotted wood-alga-fungus:: the history and life of Prototaxites Dawson 1859

The Devonian flora discovered and collected by W.E. Logan in 1843 remained unstudied until 1855 at which time the collections were offered to J.W. Dawson. His attention was immediately drawn to a single large specimen in the collections, which he identified and described as partially rotted wood of a conifer (Dawson, 1857). He proposed the name Prototaxites (Dawson, 1859) thereby expressing his concept of the genus. That concept remained unchallenged until Carruthers (1872) heatedly ridiculed both the name and the author and illegitimately substituted the name Nematophycus. His subjective opinion was that the fossil represented a fragment of a very large alga, like Lessonia. His classification, challenged only once (Church, 1919), persisted in all subsequent reports. Dawson remained adamant in his definition of Prototaxites until he illegitimately substituted the name Nematophyton for Prototaxites (Dawson, 1888) and denied (Dawson, in Penhallow, 1889) that he had ever classed the genus with the conifers. The names Nematophycus and Nematophyton are later synonyms of Prototaxites and, although inappropriate in connotation, Prototaxites is nomenclaturally valid. No undoubted original nor associated specimens are available for choice of a lectotype. This report has a triple purpose: (1) to name, as neotype, a recognizable specimen collected by Dawson for which the locality and stratigraphic data are known, (2) to redescribe the genus as structurally composed of three interactive forms of hyphae, i.e. large thin-walled, septate, branching, generative hyphae; large thick-walled, non-septate, skeletal hyphae; and small thin-walled, septate, branching, binding hyphae, which combine to form a gigantic, phototropic, amphigenous, perennial sporophore with saprobic nutrition, and (3) to classify it in the Kingdom Fungi. Generic synonymy with Prototaxites is proposed for Nematophycus (Carruthers, 1872). (C) 2001 Elsevier Science B.V. All rights reserved.