A Reinvestigation of the Cladoxylopsid Pseudosporochnus nodosus Leclercq Et Banks from the Middle Devonian of Goe, Belgium

Abstract

Reinvestigation of the morphology of the cladoxylopsid Pseudosporochnus nodosus Leclercq et Banks 1962 from the Middle Devonian (upper Eifelian) of Goe, Belgium, has established the following novel results: (1) lateral branching systems (fronds of Leclercq and Banks) have diverse morphologies, ranging from being composed of a distally dichotomous central axis bearing four to eight pairs of subopposite to alternate three-dimensionally dichotomous ultimate branching units, to simple three-dimensional dichotomous trusses; (2) these lateral branching systems are arranged three-dimensionally and irregularly on their parent branches; (3) prominent paired dichotomous lateral branching systems (perhaps aphlebia) may occur below the dichotomy of some distal branches. Our investigations therefore emphasize the primitive and variable nature of branching in this plant. An emended diagnosis for the species is proposed. Comparison with the permineralized Pseudosporochnus hueberi Stein et Hueber 1989 suggests a close yet not exclusive match between the morphology of P. nodosus and the morphology predicted from the anatomical model of P. hueberi. The well-known reconstruction of P. nodosus by Leclercq and Banks is reconsidered.