Phylum Porifera Grant, 1836 - sponges Subphylum Hexactinellida Schmidt, 1870 see Class Hexactinellida Schmidt, 1870 Class Hexasterophora F.E. von Schulze see Subclass Hexasterophora Schulze, 1886 Order Lyssacinosida Zittel, 1877 Family Rossellidae Schulze, 1885 Subfamily Acanthascinae Schulze, 1897 Genus Rhabdocalyptus Schulze, 1886 Rhabdocalyptus arcticus Brøndsted, 1916