Affinities of freshwater putative chantransia stages (Rhodophyta) from molecular and morphological data

Abstract

W.B. Chiasson, N.J. Sabo and M.L. Vis. 2005. Affinities of freshwater putative chantransia stages (Rhodophyta) from molecular and morphological data. Phycologia 44: 163–168.Fourteen putative bluish chantransia isolates were collected from locations in French Guiana (9), Brazil (1), Bolivia (1) from South America, and Mississippi, USA (3) in North America. Morphometric analyses were conducted on all isolates and partial (1282 bp) rbcL gene sequence data were obtained from 11 specimens. One isolate fit the morphological description of Audouinella pygmaea or ‘Chantransia pygmaea’ and had smaller cell dimensions and monosporangium diameter than the other isolates. The other 10 specimens varied in morphology, but were within the circumscription of A. macrospora or ‘C. macrospora’. Sequence data confirmed that the ‘pygmaea’ isolate was the chantransia of Batrachospermum ambiguum and the ‘macrospora’ isolates were chantransia of B. macrosporum. The results of this study strongly support that ‘C. macrospora’ represents a single species, B. macrosporum, but only a small number of freshwater red algal taxa have been analysed using either culture or genetic data, and more taxa with this chantransia morphology may be found. With only the present gene sequence data, it is difficult to ascertain whether the ‘pygmaea’ morphology represents only the chantransia of B. ambiguum or, more likely, numerous species. The B. macrosporum chantransia was in numerous streams in which no gametophytes of this taxon were collected, but gametophytes of other Batrachospermum species were present. Therefore, caution should be used in assuming that the macroscopic chantransia in a stream is the alternate life history phase of the gametophytes present. There was sequence variation among the B. macrosporum chantransia isolates and even between a chantransia isolate and gametophyte from the same stream segment, possibly suggesting that the diploid chantransia may serve as a repository for genetic variation.