Open AccessA new cycad stem from the C retaceous in A rgentina and its phylogenetic relationships with other C ycadales
Author(s) -
Martínez Leandro Carlos Alcides,
Artabe Analía Emilia Eva,
Bodnar Josefina
Publication year - 2012
Publication title -
botanical journal of the linnean society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.872
H-Index - 68
eISSN - 1095-8339
pISSN - 0024-4074
DOI - 10.1111/j.1095-8339.2012.01300.x
Subject(s) - cycad , biology , genus , botany , cretaceous , phylogenetic tree , pith , xylem , evolutionary biology , paleontology , biochemistry , gene
The cycads are an ancient group of seed plants. Fossil stems assigned to the C ycadales are, however, rare and few descriptions of them exist. Here, a new genus of cycad stem, W intucycas gen. nov. , is described on the basis of specimens found in the A llen F ormation ( U pper C retaceous) at the S alitral O jo de A gua locality, R ío N egro P rovince, A rgentina. The most remarkable features of W intucyas are: a columnar stem with persistent leaf bases, absence of cataphylls, a wide pith, medullary vascular bundles, mucilage canals and idioblasts; a polyxylic vascular cylinder; inverted xylem; and manoxylic wood. The new genus was included in a phylogenetic analysis and its relationships with fossil and extant genera of C ycadales were examined. In the resulting phylogenetic hypothesis, W intucycas is circumscribed to subfamily E ncephalartoideae, supporting the existence of a greater diversity of this group in S outh A merica during the C retaceous. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society , 2012, 170 , 436–458.