Anapaulia moodyi gen. et sp. nov.: a probable iridopteridalean compression fossil from the Devonian of western Venezuela

Abstract

Compression fossils of a new plant, Anapaulia moodyi Berry et Edwards, gen. et sp. nov., are described from the Middle or Upper Devonian of western Venezuela. The main novel characteristic of this plant is that the monopodial main axis has both large second-order axes as well as smaller dichotomizing branches inserted in a predominantly whorled arrangement, the whorls being separated by long internodes. Third-order axes and small fourth-order axes are borne in compressed helices and helices. Small ultimate branching systems, which dichotomize up to four times, are borne on the third- and fourth-order axes in helices and compressed helices. Elliptical sporangia are borne upon the recurved tips of ultimate branching systems otherwise similar to the sterile examples. The entire plant up to the second or third divisions of the ultimate branching systems is covered with fine spines. The nature of the whorled arrangement of branching in the first-order axes sets the plant apart from the Trimerophytina and other contemporary and earlier land plants. A close comparison can be drawn with permineralized stems from the Middle Devonian of North America belonging to Iridopteridales Stein, which show anatomical traits which may correspond to the branching patterns found in Anapaulia. There are morphological similarities to compression fossils of the iridopteridalean Ibyka Skog et Banks, for which both permineralizations and a limited amount of compression material was described. Anapaulia is thus tentatively assigned to the Iridopteridales.