REINVESTIGATION OF THE CLADOXYLOPSID PSEUDOSPOROCHNUS-NODOSUS LECLERCQ ET BANKS FROM THE MIDDLE DEVONIAN OF GOE, BELGIUM

Reinvestigation of the morphology of the cladoxylopsid Pseudosporochnu s nodosus Leclercq ct Banks 1962 from the Middle Devonian (upper Eifel ian) of Goe, Belgium, has established the following novel results: (1) lateral branching systems (''fronds'' of Leclercq and Banks) have div erse morphologies, ranging from being composed of a distally dichotomo us central axis bearing four to eight pairs of subopposite to alternat e three-dimensionally dichotomous ultimate branching units, to simple three-dimensional dichotomous trusses; (2) these lateral branching sys tems 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 branche s. Our investigations therefore emphasize the primitive and variable n ature of branching in this plant. An emended diagnosis for the species is proposed. Comparison with the permineralized Pseudosporochnus hueb eri Stein et Hueber 1989 suggests a close yet not exclusive match betw een the morphology of P. nodosus and the morphology predicted from the anatomical model of P. hueberi. The well-known reconstruction of P. n odosus by Leclercq and Banks is reconsidered.