A taxonomic revision of the late Paleozoic lyginopterid Sphenopteridium germanicum and description of its globose-stem growth habit

A specimen of the lyginopterid pteridosperm Sphenopteridium germanicum (Weiss) Kerp et DiMichele comb. nov. was discovered at Late Pennsylvanian (Missourian/Kasimovian) Kinney Quarry, New Mexico, complete from roots to crown attached leaves. Taxonomic review, based on vegetative and associated reproductive organs, supports Mamay's assignment Schimper. However, species, manzanitanum Mamay is vegetatively identical Sphenopteris germanica Weiss. We review germanica, concluding that it should be assigned Sphenopteridium, S. considered a later homonym, placed in synonymy germanicum. Arnophyton kuesii obviously juvenile version same species. The principal study has growth habit consisting short, subterranean or surficial, mound-like stem bearing tuft ascendant leaves vertically disposed taproot, so low-growing, upright form. sufficient size suggest this mature configuration, but does not represent maximum species could attain, excavated much larger than those found attachment. Inferred its sedimentary context, likely growing along river estuary bank incorporated whole as eroded collapsed, resulting transport into embayment which flora fauna were preserved. plants were, thus, relatively small low growing; there no evidence laterally initiated stems plantlets indicative clonal reported here new, enlarging range architectures known late Paleozoic plants, thus spotlighting morphological richness had evolved by time, despite significantly lower diversity modern world.