Development of the enigmatic peristome of Timmia megapolitana (Timmiaceae; Bryophyta)

• DOI: 10.3732/ajb.94.3.460
• Publication Date: 2008-02-29T22:42:44Z
• Authors: Jessica M. Budke; Cynthia S. Jones; Bernard Goffinet
• Keywords: Bryopsida; Lineage (genetic); Sporophyte; Character evolution

The Timmiaceae (Bryophyta) have been traditionally classified within the Bryales based on peristome architecture. Phylogenetic analyses of nucleotide sequences revealed relationships that are incongruent with this hypothesis and implicated an origin for lineage early in radiation arthrodontous mosses (Bryopsida). This unexpected phylogenetic placement raises important questions about evolutionary significance Timmia peristome, which differs from all other by 64 isomorphic filaments topping endostomial membrane. A developmental study megapolitana was undertaken to examine alignments anticlinal cell walls inner peristomial layer (IPL) those primary (PPL), a character has used define major lineages. Criteria were established assessing longitudinally homologous regions contribute peristome-forming region. Young sporophytes examined using histological techniques, alignment wall divisions quantified. Critical IPL T. determined be symmetrical, similar patterns Funariales. research provides novel observations putative ancestral mosses, reevaluates criteria compare studies different lineages discusses implications these observations.