Lilingostrobus chaloneri gen. et sp. nov., a Late Devonian woody lycopsid from Hunan, China

Abstract

Lycopsids are a minor component of current terrestrial herbaceous floras. However, lycopsid fossil diversity shows a great diversity and disparity including heterosporous woody plants, e.g. the giant isoetaleans that populated the extensive Pennsylvanian wetlands. The earliest known isoetaleans come from late Devonian localities from China. Here, we describe Lilingostrobus chaloneri gen. et sp. nov., a new isoetalean lycopsid from the Upper Devonian (Famennian) Xikuangshan Formation of China (Hunan Province, South China), which adds to the already impressive diversity of the Devonian lycopsids from China. Lilingostrobus shows an unusual combination of characters. This new plant is pseudoherbaceous, with a possible tufted habit, and consists of narrow axes with rare isotomies. The stem includes small quantities of secondary xylem. Each fertile axis bears one terminal strobilus comprising sporophylls ending in a very long upturned lamina. Microspores and putative megaspores have been found, but whether the plant has mono- or bisporangiate strobili is unknown. Importantly, our cladistic analysis identifies Lilingostrobus as a direct precursor of Isoetales, which provides new insights into the early evolution of lycopsids.

No phylogenomic support for a Cenozoic origin of the “living fossil” Isoetes

“…Our second calibration, the split between extant Selaginellaceae and Isoetaceae, was constrained using a uniform prior age distribution with a maximum age of 485 Myr (same as our root node) and a minimum age of 358 Myr. The minimum age is based on multiple occurrences of isoetalean arborescent lycopsids in deposits of Late Devonian (Famennian) age (Pigg, 2001 ; Wang and Berry, 2003 ; Cressler and Pfefferkorn, 2005 ; Prestianni and Gess, 2014 ; Gerrienne et al, 2018 ). Morris et al ( 2018 ) treated the fossil taxa considered here less conservatively than we have.…”

“…Leclercqia complexa Banks (Banks et al, 1972 ), a homosporous but ligulate plant, has been documented from the Emsian (late Early Devonian) of Canada (Gensel and Albright, 2006 ; Wellman et al, 2009 ) and indicates a minimum of 392 Myr since the split between the Lycopodiaceae and a ligulate clade comprising Leclercqia and the extant lineages Isoetaceae and Selaginellaceae (Kenrick and Crane, 1997a ; Wellman et al, 2009 ; Morris et al, 2018 ). Isoetalean arborescent fossils, including their “rhizomorph” shoot structure producing stigmarian rootlets, are known at least from the Famennian (late Late Devonian) (Pigg, 2001 ; Wang and Berry, 2003 ; Cressler and Pfefferkorn, 2005 ; Taylor et al, 2009 ; Prestianni and Gess, 2014 ; Hetherington and Dolan, 2017 ; Gerrienne et al, 2018 ; DiMichele et al, 2022 ). The fossils indicate a minimum of 358 Myr since the split between extant Isoetaceae and Selaginellaceae (Bateman, 1992 ; Bateman and DiMichele, 1994 ; DiMichele and Bateman, 1996 ; Kenrick and Crane, 1997a ; Hetherington and Dolan, 2017 ).…”

Reinvestigation of the Late Devonian Lycopsid Sublepidodendron grabaui from Anhui Province, South China

“…Changxingia longifolia is also reported from the Upper Devonian (Famennian) of South China and is interpreted as a small-sized lycopsid with monosporangiate strobili [ 10 , 15 ]. Its rhomboidal leaf cushions and oblanceolate leaf bases are helically arranged on the stems.…”

“…Middle Devonian lycopsids evolved many key characteristics, e.g., the heterospory [ 4 , 5 ] and the tree habit [ 6 , 7 ]. Heterosporous lycopsids blossomed in the Late Devonian (e.g., [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]), which is regarded as a major step in the full colonization of land surfaces by plants [ 17 , 18 ]. In the past 20 years, over ten species of Late Devonian heterosporous lycopsids have been reported or restudied all around the world (e.g., [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 19 , 20 , 21 , 22 ]); especially, the South China Plate held eight species with monosporangiate strobili (e.g., [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]), suggesting a probable origin center and diversity hotspot of this group.…”

A factor analysis approach to modelling the early diversification of terrestrial vegetation

“…Subsequently, plant fossil data were extracted from the Paleobiology Database via Fossilworks (http://fossilworks.org/) which were cross-checked against the primary references and, when possible, more recent literature. Lastly, numerous taxa were added from the primary literature, particularly recently described genera such as Lilingostrobus, Rinistachya, Kossoviella, Guangdedendron, Qianshouia or Keraphyton (Gerrienne et al, 2018;Prestianni and Gess, 2018;Orlova et al 2019;Wang et al, 2019;Huang et al, 2020;Champreux et al, 2020).…”