Are All Paraphyllia the Same?

Abstract

Moss paraphyllia, the trichome-like or foliose structures on moss stem surfaces, are usually treated as epidermal outgrowths. However, in some taxa of the moss families Leskeaceae, Neckeraceae, and Amblystegiaceae their distribution along the stem is consistently correlated with parts of the stem surface near branch primordia. In other moss families, Climaciaceae, Hylocomiaceae, and Pseudoleskeaceae the specific paraphyllia-generating epidermal layer produces paraphyllia evenly all along the stem. These results suggest that there are at least two different types of regulation of paraphyllia development; however, both of them may be involved in the morphogenesis of paraphyllia in some families, for example in the Thuidiaceae. Exogenous abscisic acid treatment consistently increases the number of paraphyllia of the Leskea-type, and it also induces the development of proximal branch leaves that normally do not develop a lamina above the stem surface. This fact supports conclusions regarding the homology of the Leskeatype of paraphyllia with leaves.

The moss traits that rule cyanobacterial colonization

“…Hence, focusing on moss leaves as colonization sites could vastly underestimate cyanobacterial colonization along moss shoots. Paraphyllia occur in taxa of only a few moss families, such as Hylocomiaceae, Thuidiaceae and Brachytheciaceae ( Spirina et al ., 2020 ). If those taxa that have paraphyllia host more cyanobacteria than taxa without these structures is an open question.…”

Neckera, Forsstroemia and Alleniella (Neckeraceae, Bryophyta) redefined based on phylogenetic analyses

“…In the latter type the paraphyllia are distributed all over the stems and branches, but in the former paraphyllia occur only near branch primordia. Spirina et al (2020) made close observations on the paraphyllia development in Leptodon smithii, and visually observed their distribution in Metaneckera menziesii and Neckera californica, and in all of those the paraphyllia represented the Leskea-type. While we have not made comprehensive studies on the paraphyllia in the Neckeraceae, observations on numerous species by the author Enroth suggests that in this family they are exclusively of the Leskea-type.…”

“…& Arn., Leptodon, Alleniella, some species of Forsstroemia). Spirina et al (2020) studied the development and location of paraphyllia in various genera of pleurocarpous mosses. Based on where the paraphyllia are located, those authors divided them into two groups they called Leskeatype and Climacium-type.…”

A further range extension of Redfearnia (Bryophyta, Amblystegiaceae), with new data on its phylogenic position

“…We refer Redfearnia to the Amblystegiaceae, because: (1) it belongs to this family in all but one of the singlemarker trees (Figs. 3-7); (2) it has proximal branch leaves occurring around dormant buds, whereas in the Plagiotheciaceae branch primordia remain for a long time leafless or 'naked' [we avoid the term 'pseudoparaphyllia,' which is applied to non-homologous structures (Spirina et al, 2020)]; and (3) costa extending to mid-leaf in perichaetial leaves, whereas in the Plagiotheciaceae costa in perichaetial leaves is absent or thin and indistinct. We failed to find in Redfearnia any morphological features that would suggest its placement in Plagiotheciaceae rather than in Amblystegiaceae.…”