Revision of Dendraena pinnatilobata Němejc from the Pennsylvanian of the Czech Republic

Abstract

pinnatilobata Němejc is a Pennsylvanian true fern, which is known from the Stradonice locality (Czech Republic) only. All specimens of Dendraena pinnatilobata are preserved as three-dimensionally in volcaniclastic of Whestone Horizon (Radnice Member, Kladno Formation). Revision of this species includes detail study of pinnae and pinnules morphology, sporangia, in situ spores and a rachial anatomy. Combination of several methods was used including camera lucida, maceration of sporangial/spores, SEM observation and cross sections of rachides for precise description of this species. D. pinnatilobata pinnae were borne on the rachides of the Anachoropteris robusta-type anatomy. This real organic connection between pinnae/pinnules (including reproductive organs) and rachial anatomy is rare in fossil record. This knowledge is very important for understanding of a leptosporangiate fern evolution. Sporangia of Dendraena pinnatilobata are annulate with band-lateral-upper type of annulus and in situ spores of the Microreticulatisporites harrisonii type, described for the first time, are unique for D. pinnatilobata. Based on this type of sporangia the species belongs to the leptosporangiate ferns. According to the petrological and sedimentological study of host sediments it is possible to infer that specimens of Dendraena were transported a short distance. Transport was very fast and fossils were deposited in supercritical conditions, which resulted in rapid burial of the plants and their excellent preservation. The plant host rock -Whetstone Horizon -also contains abundant volcaniclastic components. D. pinnatilobata grew in close proximity to the riverside or the peatland margins.•

Maiaspora: a new miospore genus with enigmatic sculpture from the late Visean of European Russia

“…Comparable in situ spores from Dendraena pinnatilobata were described in different states with large microspores with triangular–convex outlines, and smaller ones with triangular–concave outlines (Frojdova et al . 2017). It seems unlikely that these differences were caused by maturation processes, as suggested by the authors.…”

“…Frojdova et al . (2017) reported in situ spores from sporangia of the fern Dendraena pinnatilobata Němejc from the middle Moscovian of Stradonice, southeast of the Kladno‐Rakovnik Basin, Czech Republic. In this material the reticulum has tapered muri and polygonal lumina, 1 μm in diameter.…”

“…1997) and Anachoropteridaceae (Frojdova et al . 2017). Despite this, the sculpture types are very variable, from spinate–granulate, verrucate–rugulate to microreticulate with mamelons.…”

Revision of Pennsylvanian genus Sturia Němejc and its spores (Duckmantian, Czech Republic)

“…Dendraena pinnae were borne on the rachides of the Anachoropteris robusta-type and therefore falls in the family Anachoropteridaceae (Frojdová et al 2017b). The anatomy of Sturia is unknown but the in situ spores are very different, and we can exclude a relationship with Dendraena.…”

Maiaspora: the hallmark of gleichenioid ferns (Gleicheniales) from the early Carboniferous

“…The question remains as to whether the stem group of Gleicheniales emerges as a result of the first radiation in leptosporangiates. This first divergence resulted in several stem groups (families) including the Anachoropteridaceae, Botryopteridaceae, Kaplanopteridaceae, Psalixochlaenaceae, Sermayaceae and Tedeleaceae, and several incertae sedis genera including Discosoropteris, Sturia and Tenchovia (Eggert & Delevoryas 1967;Rothwell & Stockey 2008;Taylor et al 2009;Galtier & Phillips 2014;Frojdova et al 2017aFrojdova et al , 2017bSessa 2018;P seni cka et al 2022). However, none of these groups assembled the morphological characters that are apomorphic for the Gleicheniales.…”