Cell Division Patterns in the Peristomial Layers of the Moss Genus Two Hypotheses and a Third Solution.

The Chilean endemic genus belongs to the Gigaspermaceae, one of the most basal groups of arthrodontous mosses. While none of the species in this family has a peristome, earlier stages of sporophyte development often disclose its basic structure. The study of sporophytes at the early stages of development was conducted to identify possible similarities with , the genus sister to Gigaspermaceae plus all other arthrodontous mosses in the moss phylogenetic tree. shares a strongly unequal cell division pattern with the Dicranidae. In groups more closely related to , as it is the case of , this pattern is not known. Our study of found only irregular presence of slightly unequal cell divisions that may then be considered as a plesiomorphic state in peristomate mosses. The most frequently present pattern revealed in is common with the Polytrichaceae, a more basal moss group with nematodontous peristomes.