Parasporotheca, Gen. Nov., and Its Bearing on the Interpretation of the Morphology of Permineralized Medullosan Pollen Organs

Abstract

PARASPOROTHECA [P. leismanii sp. nov. is a large mass of synangiate microsporangiate organs attached to frond axes demonstrating medullosan anatomy. The specimen, of Late Pennsylvanian age, consists of several orders of frond axes, terminating within the fertile region. The frond axes share features with Sutcliffia- and Myeloxylon-type fronds but are not identical with either of these types. Several orders of lateral branching occur which terminate in dichotomized ultimate axes. These axes contain a single vascular bundle and serve as the stalks of terminally borne synangia. The fertile region is considered to be a type of compound synangium consisting of concentrically arranged synangia that are tightly appressed by interlocking epidermal projections. The individual synangia are ventrally concave laminate structures with a single row of 14-20 radiating, elongate, tubular sporandia that contain numerous prepollen grains of the Parasporites type. Features of Parasporotheca are compared with those of other permineralized medullosan pollen organs, and the internal structure of Dolerotheca is reinterpreted.