Chromosome Studies of Brazilian Ferns

Abstract Chromosome numbers, habitat and general geographic distributions are reported for a sample of ferns from the vicinity of Manaus. These numbers are compared with those reported for species in other regions. The report of n=ca. 154 for Schizaea incurvata is the first record of the genus in the American tropics and the others are first counts of these species in continental South America. In Lindsaea n=42 and n=ca. 84, are somewhat lower and appear to represent a line distinct from the species of the paleotropics with n=47. In Trichomanes n=32, 64 and 128 appear to be levels of polyploidy based on X=8, while n = 72 is possibly based on X=9 and suggest possible diverse lines in the genus. Pityrogramma calomelanos with n=116 is considered as an octoploid based on X=29. Our sample covering about ten percent of the pteridophytes in the area we collected, yielded numbers ranging between n=32 and n=154, and generally appears to represent high polyploid levels.