The systematics of the green algal class Ulvophyceae have been difficult to resolve with ultrastructural and molecular phylogenetic analyses. Therefore, we investigated relationships among ulvophycean orders by determining the distribution of two discrete genetic characters previously identified only in the order Dasycladales. First, Acetabularia acetabulum uses the core translation GTPase Elon...

Molecular evolutionary rates within two protistan and three metazoan taxa were estimated using divergence times derived from fossil records. The results indicate that the small-subunit rRNA sequences within Dasycladales (Chlorophyta) and Bacillariophyceae evolved at a rate approximately two to three times faster than that estimated within Echinodermata, Mollusca, and Actinistia-Tetrapoda. It wa...

1 adresse actuelle: PDD/Zakum, ADMA-OPCO, P.O.Box303, Abu Dhabi, UnitedArab Emirates ([email protected]); adresse permanente: Le Clair Côteau, 14-A Rue de la Guaize, 28130 Maintenon, France. 2 Institute of Geology, Sachsova 2, P.O.Box 268, HR-10000 Zagreb, Croatia. Abstract The present work enlists as comprehensively as possible the Permian and Triassic Dasyclad algae. For each species, local...

The Dasycladalian algae produce diverse whorled structures, among which the best-known are the reproductive whorl (cap) and the vegetative whorls (hair whorls) of Acetabularia acetabulum. The origin of these structures is addressed in terms of three pattern forming mechanisms proposed to explain whorl formation. The mechanisms involve either: mechanical buckling of the cell wall, reaction-diffu...

Dasycladales are relatively abundant in the bedded limestones of the Bidestan and Howz-e Khan members of the Late Triassic Nayband Formation in central Iran. In a locality south of the town of Naybandan (northwest of Dig-e Rostam), several Rhaetian dasycladacean algae were found in thin sections. The following taxa are described: Diplopora phanerospora Pia, Naybandoporella rhaetica nov. gen. no...

the larger benthic foraminifera gyroconulina columellifera schroeder & darmoian, 1977 (type-locality: maastrichtian aqra formation of iraq) is described for the first time from two sections of the maastrichtian tarbur formation of the zagros fold-thrust-belt, sw iran. new details on its wall microstructure are provided. the microfacies is represented by bioclastic wacke-/pack-/grainstones with ...

The siphonous green algae are an assemblage of seaweeds that consist of a single giant cell. They comprise two sister orders, the Bryopsidales and Dasycladales. We infer the phylogenetic relationships among the siphonous green algae based on a five-locus data matrix and analyze temporal aspects of their diversification using relaxed molecular clock methods calibrated with the fossil record. The...