The tectofilosids are a group of filose amoebae with shells. These are composed of organic materials and sometimes collected debris, in contrast to the euglyphids, which produce shells from siliceous scales. The shell usually has a single opening, but in Amphitrema and a few other genera it has two on opposite ends. The cell itself occupies most of the shell. They are most often found on marsh plants such as Sphagnum. This group was previously classified as the Gromiida or Gromiina. However, molecular studies separate Gromia from the others, which must therefore be renamed. They are placed among the Cercozoa, and presumably developed from flagellates like Cryothecomonas, which has a similar test. However, only a few have been studied in detail, so their relationships and monophyly are not yet certain. In a recent classification, the group Tectofilosida was not used: Chlamydophryidae, Psammonobiotidae, Pseudodifflugiidae and Volutellidae were dispersally placed in Thecofilosea, while Amphitremidae was included in Labyrinthulomycetes. Taxonomy Order Tectofilosida Cavalier-Smith & Chao 2003 (paraphyletic) Suborder Lithocollina Cavalier-Smith 2012 Family Lithocollidae Schulze 1874 Suborder Unitremina Cavalier-Smith 2012 Family Rhizaspididae Howe et al. 2011 [Rhizaspidaceae Skuja 1948] Family Fiscullidae Dumack et al. 2017 Family Pseudodifflugiidae De Saedeleer 1934 Family Psammonobiotidae Golemansky 1974 emend Meisterfeld 2002 Family Chlamydophryidae de Saedeleer 1934 emend. Meisterfeld 2002 Family Volutellidae Sudzuki 1979 References Filosa Amoeboids