COMIA, A SEED PLANT POSSIBLY OF PELTASPERMOUS AFFINITY: A BRIEF REVIEW OF THE GENUS AND DESCRIPTION OF TWO NEW SPECIES FROM THE EARLY PERMIAN (ARTINSKIAN) OF TEXAS, C. GREGGII SP. NOV. AND C CRADDOCKU SP. NOV.

摘要

Cotnia is a widespread foliage morphogenus of probable seed plant affinity primarily known from rocks of Late Permian age, in the Angaran and Cathaysian paleobiogeographic regions. It also occurs in the Early Permian of the western Euramerican equatorial paleobiogeographic region. Vegetative features and consistent association with peltaspermous reproductive organs suggest affinity with the Peltaspermales. New material from north-central Texas allows two new species to be attributed to this genus, Comia greggii and Cotnia craddockii. Both species are uncommon elements of the Early Permian (Leonardian-Artinskian) flora. They exhibit a diagnostic form of venation typical of Comia and allied forms, in which the tertiary veins form fascicles and interfascicular groups. Ultimate veins extend from their insertion point to the laminar margin, usually with one dichotomy. They neither anastomose nor terminate in blind endings. In gross architecture, C. craddockii is once pinnate. The morphology of the frond of C. greggii is not known. The much wider, more finely veined laminae of C. greggii are clearly distinguishable from the narrow pinnules with coarser venation of C. craddockii. (Russian and Chinese translations of this abstract are available in the online edition of International journal of Plant Sciences.)