This paper reports on the April-May 1983 Projeto Flora expedition to Serra do cachimbo in northcentral Brazil, a phytogeographically poorly known area near the transition between the Amazon forest and the central Brazilian planalto. The objective of this expedition was to collect botanical specimens with special emphasis on lichens. Rock outcrops are common in this area and several soil types combined with varied topography give rise to a diversity of vegetation types including Amazon caatinga, campo rupestre, gallery forest and Amazon forest. A preliminary checklist of 91 macrolichens is provided with a discussion of ecological distribution of lichens in each habitat.

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Among some Tanzanian lichens sent to us for determination by Mr J. Lovett, a sorediate specimen of Parmelia subgenus Amphigymnia (or genus Parmotrema) proved to have rather unusual chemical properties. Most of its medulla was white on exposure, but the medullary tissue immediately below the soralia was tinged yellow to orange, giving a purple colour reaction with potassium hydroxide (K). An acetone extract was coloured bright yellow. By standard t.l.c. methods the specimen was found to contain alectoronic acid, protocetraric acid, and atranorin as well as a yellow pigment in /?p classes 7 : 6-7 : 7 giving a yellow fluorescence under longwave UV light. Co-chromatography with Xanthoria parietina showed that the pigment was identical with the anthraquinone parietin. The specimen agreed morphologically with Parmelia subarnoldii des Abb., known to occur in Tanzania (Krog & Swinscow 1981), and except for the presence of the pigment it had the same chemical properties as one of the chemical races of that species. We are uncertain whether the parietin in this specimen is of environmental or genetic origin. Its appearance in the soralia, and in a small spot on one exposed area in the medulla, did not seem to be consonant with external contamination. Its genetic origin seems more likely, and in that connection it is noteworthy that the structure of the parietin molecule (Culberson 1969: 186) is close to that of the molecules constituting the dimeric anthraquinone skyrin (Culberson 1969: 188), which occurs as an accessory substance in P. subarnoldii. The specimen at our disposal was collected in Tanga Province, Lushoto District, Shume natural forest, in the Usambara Mountains (Lovett 39). It was sterile and had no pycnidia. THE LICHENOLOGIST Vol. 14 Cryptolechia nana (Tuck.) D. Hawksw. & Dibben comb. nov.

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