EUCOMMIITHECA-HIRSUTA, A NEW POLLEN ORGAN WITH EUCOMMIIDITES POLLEN FROM THE EARLY CRETACEOUS OF PORTUGAL

A new pollen organ, Eucommiitheca hirsuta containing Eucommiidites pol len grains is described from the Early Cretaceous of Portugal. The mat erial comprises dispersed microsporangiate units and fragments of axes bearing microsporangiate units in an opposite and decussate arrangeme nt. Each microsporangiate unit consists of a slightly angular to round ed peltate scale attached centrally to a short stalk, and with whorls of sporangia around the distal part of the stalk. Sporangia are stalke d and free, with longitudinal dehiscence, and contain pollen grains si milar to the characteristic dispersed pollen genus Eucommiidites. Euco mmiitheca is comparable to Erdtmanitheca another Cretaceous pollen org an containing Eucommiidites pollen, in the peltate nature of the micro sporangiate units, but microsporangiate units in Erdtmanitheca are arr anged in dense heads and sporangia are elongate. The opposite and decu ssate arrangement of the microsporangiate units in Eucommiitheca is in accordance with the possible affinity to the Gnetales suggested earli er far Eucommiidites-producing plants based on structure of their poll en grains and seeds, but peltate microsporophylls similar to those of Eucommiitheca do not occur in the Gnetales. Eucommiitheca is compared to ether fossil reproductive organs, and the bennettitalean affinity o f the fossil Sturiella langeri is questioned in light of our new findi ngs. A new family Erdtmanithecaceae is established to accomodate Eucom miidites and the Eucommiidites-producing plants Eucommiitheca, Erdtman itheca, Erdtmanispermum, Spermatites pettensis, S. patuxensis, and All icospermum retemirum. This family is based on a unique suite of reprod uctive characters, including peltate microsporangiate units aggregated in heads or spikes, each bearing numerous sporangia in a radial arran gement; pollen grains with two lateral colpi or a ring colpus flanking a distal main colpus; and seeds with a distinct megaspore membrane se veral envelopes surrounding the nucellus, and a long, narrow micropyla r tube.