A new species of the lycopsid Gilboaphyton Arnold from the Devonian of Venezuela and New York State, with a revision of the closely related genus Archaeosigillaria Kidston

A new species of the small, probably herbaceous lycopsid Gilboaphyton Arnold is based on new material from the Devonian of western Venezuela. The excellently preserved compressions allow the following characteristics to be established: (1) the presence below the leaf bases of large oval areas of parenchymatous tissue within a toughened outer stem tissue (outer cortex) which could be infilled with sediment via the leaf traces of a partially decorticated stem to give an apparent elongate-hexagonal stem pattern in certain preservational states; (2) a pattern of elongate-hexagonal grooves delimiting the swollen leaf bases on the stem surface; (3) a characteristic leaf morphology, namely a broad lamina with two opposite distally pointing lateral teeth. Other specimens from New York State previously reported in the literature are assigned to the genus, some to the species Gilboaphyton griersonii Berry et Edwards, sp. nov., and others to the type species G. goldringiae Arnold. Understanding the details of the stem anatomy, particularly the presence of oval areas of parenchymous tissues within the outer cortex, allows the reinterpretation of the type specimen of the well known Devonian lycopsid Archaeosigillaria Kidston which also has similar cortical features, but lacks leaves. Rather than extending the already confused concept of Archaeosigillaria we have chosen to place the new Venezuelan and other leafy material within a genus for which both leaf morphology and stem surface pattern are now known (Gilboaphyton). A comprehensive review of the genus Archaeosigillaria ia demonstrates that the majority of recorded specimens do not share diagnostic characters with the type specimen, and are therefore excluded from the genus.