Phylum: Charophyta   Family: Desmidiaceae

Staurastrum hibernicum West

Since West senior named this species in 1892 the Wests (1912) subsequently regarded it as a variety of Staurastrum orbiculare and note: "This is the largest form of St. orbiculare and is principally characterized by the more pronounced basal angles of the semicells and the flattened apices." It has since been returned to its original designation. Status for the Outer Hebrides is uncertain but is thought to be rare

References: 
West, W. & West, G.S. (1912) A Monograph of the British Desmidiaceae, Volume 4
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus