STUDIES OF PALEOZOIC MARATTIALEANS: THE MORPHOLOGY AND PROBABLE AFFINITIES OF TELANGIUM PYGMAEUM GRAHAM

Telangium pygmaeum Graham is known from Upper Pennsylvanian coal balls from the Calhoun coal mine (Illinois). The species was described as possessing radial synangia consisting of 3-5 sporangia fused laterally for about 1/3 their length. Synangia were believed to be sessile and borne terminally or laterally on a branching rachis without lamina. Examination of new coal ball material of the same age indicates that the synangia are borne abaxially on the pinnules of a compound frond with the anatomy of a Psaronius leaf (Marattiales). Synangia are sessile and borne in two rows, one on either side of the pinnule midrib, under the unbranched lateral veins. Synangia are radial, 0.6 mm in diam, and consist of a ring of thin-walled sporangia fused to near their apices prior to dehiscence, but separating on dehiscence to release spores along their inner midline. Spores are spherical, trilete, 30-48 ,um in diam, with a granulate ornamentation. The new genus Araiangium is proposed for this material based on the organization of the sessile thin-walled synangia. Araiangium is compared with other marattialean genera with sessile synangia (Acaulangium, Acitheca), and with the pedicellate synangia of various species of Scolecopteris. Criteria used in the delimitation of genera in Paleozoic anatomically preserved marattialean fertile foliage are discussed. TELANGIUM PYGMAEUM GRAHAM (1934) is a portion of a fertile coal ball plant from the Upper Pennsylvanian of Illinois. The generic name implies that it is a pollen organ belonging to the lyginopterid seed ferns, and was described as consisting of sessile radial synangia borne on a naked branching system. Specimens of Telangium from the Upper Mississippian have