Tenuisa frasnianagen. et sp. nov., a Plant of Euphyllophyte Affinity from the Late Devonian of China

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The University of Chicago Press is collaborating with JSTOR to digitize, preserve and extend access to International Journal of Plant Sciences.Tenuisa frasniana gen. et sp. nov. is reported from the Late Devonian (Frasnian) Hunan Province of South China. Its axes are naked and narrow. Fertile stem is pseudomonopodial in branching and bears distichous lateral units. Fertile lateral units are subopposite and pseudomonopodial in the proximal part of stem, while they are alternate and isotomous two to four times in the distal part. They have tiny terminal sporangia that are paired and fusiform and that possess pedicels. Sterile ultimate units are dichotomous and terminate in tips recurving oppositely. Tenuisa resembles Psilophyton in pseudomonopodial fertile stem with alternate and dichotomous lateral units terminated by paired and vertically elongate sporangia. However, fertile lateral units are subopposite and pseudomonopodial on the basal part of stem, sporangial pedicels are present, and neither sporangial pairs nor sporangia themselves are twisted. This new plant differs from iridopteridalean cladoxylopsids mainly in the absence of whorled laterals and axial spines, and it differs from pseudosporochnalean cladoxylopsids in the absence of digitate lateral branches and the presence of sterile ultimate units with recurved tips. Because of these morphological differences and a lack of anatomical information, Tenuisa frasniana is currently left as incertae sedis within Euphyllophytina (sensu Kenrick and Crane).

Denglongia hubeiensis gen. et sp. nov., a New Plant Attributed to Cladoxylopsida from the Upper Devonian (Frasnian) of South China

“…Wang (2008) emphasizes the similarities between the iridopteridaleans and pseudosporochnalean cladoxylosids on the basis of their paired terminal sporangia and similar morphology of fertile/sterile ultimate appendages. The disagreements lie in the recognition of potential synapomorphies, the delimitation and monophyly of Cladoxylopsida, homology evaluation of certain characters, and phylogenetic relationships among the iridopterid-cladoxylopsid plants (Berry and Stein 2000;Cordi and Stein 2005;Meyer-Berthaud et al 2007;Wang 2008). Fertile characters are conspicuously lacking in these discussions, except in Wang (2008).…”

“…The disagreements lie in the recognition of potential synapomorphies, the delimitation and monophyly of Cladoxylopsida, homology evaluation of certain characters, and phylogenetic relationships among the iridopterid-cladoxylopsid plants (Berry and Stein 2000;Cordi and Stein 2005;Meyer-Berthaud et al 2007;Wang 2008). Fertile characters are conspicuously lacking in these discussions, except in Wang (2008).…”

“…This pattern is unlike that in the known iridopterid-cladoxylopsid plants. Among the known cladoxylopsids, Calamophyton, Panxia, and Rhipidophyton also have complex fertile appendages departing from the simple type seen in iridopteridaleans (Anapaulia, Compsocradus, and Ibyka) and Pseudosporochnus (Schweitzer 1973;Berry and Wang 2006b;Wang and Berry 2006); in the latter two groups, the fertile appendages show a branching pattern similar to that in sterile appendages but with the sterile tips partially or entirely replaced by sporangia (Leclercq and Banks 1962;Berry and Stein 2000;Wang 2008). The fertile appendage of Calamophyton has two sporangiophores, and each bears two sterile extensions and three lateral recurved stalks with paired fusiform sporangia (Leclercq 1969;Schweitzer 1973).…”

“…Moniliformopses, the sphenopsid-fern clade, is characterized by the presence of ''peripheral permanent protoxylem,'' and Radiatopses is united in part by the presence of ''radiate protoxylem'' (Beck and Stein 1993). The Iridopteridales and Cladoxylopsida are two basal groups of Moniliformopses attracting much more recent attention (Berry and Stein 2000;Cordi and Stein 2005;MeyerBerthaud et al 2007;Stein et al 2007;Wang 2007;Wang and Lin 2007;Wang 2008) and are significant for investigations of the origin, early diversification, and evolution of ferns or sphenopsids (Stewart and Rothwell 1993;Taylor and Taylor 1993).…”

A new euphyllophyte Kunia venusta gen. et sp. nov. from the Middle Devonian of Yunnan, South China

“…However, Tsaia is characterized by spiny axes chiefly in anisotomous branching and spine‐like tips of sporangia. Similar to Kunia , Tenuisa (Wang, 2007) has pseudomonopodial first‐order fertile axes, terminal fusiform sporangia in pairs, and sterile appendages with recurved tips. In contrast, the first‐order axes of Tenuisa bear organs in a distichous arrangement (subopposite or alternate), and the sporangia possess distinct pedicels.…”