Polyssaieviaceae

Name

Polyssaieviaceae

Rank

Family

Authors (Name)

Ignatov M. S.  

Authors (Pub.)

Ignatov M. S. Voronkova T. V. Spirina U. N. Polevova S. V.  

Publication

How to recognize mosses from extant groups among Paleozoic and Mesozoic fossils [2024/10]

Journal

Diversity

Volume

16

Issue

10(622)

Page number

16

Year

2024

Parent Taxon

[Order] Protosphagnales

Type

[Genus] Polyssaievia

Diagnosis

Stems regularly pinnate branched. Leaves erect to spreading, straight or recurved near leaf middle, from the broadly ovate base gradually narrowed into lanceolatetriangular upper part, rounded to base; margin entire, bordered by unistratose, 1–2-seriate limbidium, limbidium cells indistinctly differentiated; laminal cells in distal leaf part elongate to linear, with narrowly acute upper and lower ends, towards the leaf base shorter, rectangular or rhombic, monomorphic throughout the leaf or forming ‘net venation’ by narrow, usually two cell wide veins formed by longer and darker cells; veins spreading from the base and far in the lamina, ending among laminal cells or fused, but never reaching the leaf margin and never extending into the upper part of the leaf, where all cells are narrow; vein expression varies from the most pronounced development when veins occur throughout the broadened basal part of the leaf and are absent only in the most distal part, to the ‘net venation’ characterized by only few veins near the leaf base, or it is totally absent, at least in most leaves. Distinct oblique rows of laminal cells sometimes present, but within the areas with ‘net venation’ the rows are not as long as in leaves where the ‘net venation’ is poorly developed or undeveloped. Sphagnalean areolation pattern rarely expressed; when present, it is seen in a few areas near the leaf base as alternating cells rows where cells in neighboring rows are elongated perpendicularly.