Abstract

A study of modern sediment from the Western Arctic has revealed the pres-ence of a distinctive brown-colored cyst with a spherical central body bearingunbranched processes that are usually solid with a small basal pericoel.Distinctive barbs project from some processes, and process tips are usuallyminutely expanded into conjoined barbs. The archeopyle is apical and saphopy-lic. This cyst corresponds to Islandinium? cezare morphotype 2 of Head et al.(2001, J. Quat. Sci., 16:621). Phylogenetic analyses based on the small andlarge subunit rRNA genes infer close relationship with Islandinium minutum ,the type of which is that of the genus. Re-examination of specimens of I. min-utum reveals the presence of minute barbs on its processes, but differenceswith Islandinium? cezare morphotype 2 remain based on size, process distribu-tion, and barb development. Furthermore, the internal transcribed spacershows I. minutum to be distinct from this morphotype. On the basis of thesesmall but discrete differences, we propose the new subspecies Islandiniumminutum subsp. barbatum subsp. nov. Molecular sequencing of other cystsencountered, namely Echinidinium karaense, an unidentified flattened cyst,and “Polykrikos quadratus”, places them in the Monovela clade, the lattershowing greater morphological variability than previously thought.