| Summary: | Henri Van Heurck examined a sample collection of sea ice and underlying sea floor sediment material during the Belgian Antarctic Expedition (1897-1899). He described eight new taxa of the monoraphid diatom genus Cocconeis from this collection including: C. antiqua var. tenuistriata , C. gautierii var. gautierii and var. inornata , C. heydrichii , C. japonica var. antarctica , C. litigiosa , C. schuettii var. schuettii and var. minor . All these Cocconeis taxa share well-silicified sternum valves with wide, apical hyaline areas, more or less lenticular in shape, and narrow hyaline bands at mid-distance between the apical axis and the margin, while the more delicate raphe-sternum valves bear uniseriate striae, a hemistauros associated with the central raphe area, and crescent-shaped terminal hyaline areas. Since their original description in the early 20th century, these Cocconeis taxa have been rarely reported. I studied newly described Cocconeis taxa from Van Heurck's type material by light microscopy. The main valve features of C. gautierii var. gautierii and var. inornata , C. litigiosa , and C. schuettii var. schuettii and var. minor agree well with those of Cocconeis antiqua I propose these five taxa be reduced to synonymy of C. antiqua .
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