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Abstract
Surface features of mature sporoderm in Fossombronia caespitiformis, F. wondraczeckii, F. angulosa and F. echinata (Metzgeriales, Codoniaceae) were examined by scanning electron microscopy (SEM). Sporoderm layering of fresh-fixed and acetolyzed spores was studied by trasmission electron microscopy (TEM). Surface ornamentations of spores consist of spine-like and/or ridge-like markings which form species-specific patterns on the distal faces. Sporoderms have similar cross-sectional configurations, which include a fibrillar intine, removable by acetolysis, and two morphologically distinct exine layers, resistant to acetolysis. The inner exine consists of lamellae, parallel to the spore surface, composed of thin, long, parallel, closely spaced laminar units. The outer exine, which produces the spore surface ornamentations, is formed of thick, shorter, parallel, tightly appressed laminar units, impregnated with very dense material and variably oriented with respect to the inner exine lamellae. The internal sporoderms also subject to species variability. Internal sporoderm structure in Fossombronia is quite unlike that of typical Metzgeriales or Jungermanniales and approaches the configurational complexity of the Sphaerocarpales and Marchantiales.