Dendrographa

Abstract: The genus Dendrographa (Roccellaceae) is monographed. These fruticose lichenized ascomycetes are endemic to the Pacific coast of Baja California, Mexico and California, U.S.A. Two sexual species are recognized, both including anamorphic states here recognized as forms. These forms are dispersed by fragmentation. A new species. Dendrographa alectoroides and a new form, D. alectoroidesf parva are described. A new combination, Dendrographa leucophaeaf minor is made. Key, descriptions, distribution maps, and notes on chemistry and habitat are supplied. The genus Dendrographa was described by Dar- bishire (1895) and included the one species D. leu- cophaea originally described as Roccella leucophaea by Tuckerman (1858). Roccella is habitually and ecologically similar to Dendrographa. A few years later, Darbishire (1898) added a species to Dendro- grapha when he described the constantly sterile tax- on Dendrographa minor. Darbishire (1898) refered to Hasse (in litt.) who wrote that Farlow in various herbaria had regarded Dendrographa minor only as a "reduced form on rocks" of D. leucophaea. Hasse also mentioned that Farlow, obviously in agreement with Tuckerman, labelled one collection "Roccella leucophaea v. mi- nor Tuck." Thus, the question whether this taxon was to be regarded as a distinct species or not was raised already by Farlow and Tuckerman on the one hand and Darbishire on the other. That was also our original question-to investi- gate the status of the sterile Dendrographa minor versus the fertile Dendrographa leucophaea. Was Dendrographa minor to be considered as clonal pop- ulations of Dendrographa leucophaea developed by means of vegetative rejuvenation through fragmen- tation and dispersal of the outermost, ecorticate branchlets? In that case it would be parallel to the formation of clones developed from soredia as hy- pothesized by Tehler (1982). Using the terminology of Poelt (1970), this would be a "species pair" formed