POSTFERTILIZATION DEVELOPMENT AND THE NATURE OF THE CONNECTING CELL IN AGLAOTHAMNION HALLIAE (CALLITHAMNIEAE, CERAMIACEAE)

An investigation of early postfertilization stages in Aglaothamnion ha lliae (Collins) Aponte, Ballantine et J.N. Norris from North Carolina yielded results that were at variance with previously published observ ations for the tribe Callithamnieae. The earliest events were identica l with previously published reports: the fertilized carpogonium divide s longitudinally into two cells, the supporting cell and an opposite p eriaxial cell each cut off auxiliary cells, and each of the two carpog onial derivative cells cuts off a connecting cell. Following fusion of a connecting cell with an auxiliary cell, additional stages were obse rved: the diploid nucleus divides and one of the daughter nuclei enter s the auxiliary cell, while the other is extruded and cut off in an ex ternal cell that resembles the original connecting cell; the auxiliary cell cleaves transversely by an incomplete septum into a foot cell co ntaining one or two haploid nuclei and a gonimoblast initial containin g the diploid nucleus. Gonimoblasts develop in the usual manner. The a dditional postfertilization stages seen here in Aglaothamnion have not been reported previously in the Callithamnieae or elsewhere in the Ce ramiaceae.