Class Conjugatophyceae Engl. (1892) see Class Zygnematophyceae Round ex Guiry (2013)
Count: [g†g] 2o;6f;79g; †6g [3 Feb 2020]
   Order Zygnematales - filamentous conjugates and saccoderm desmids
  Count: [g] 2f;26g [3 Feb 2020]
     Family Zygnemataceae (Meneghini) Kützing (1843)
    Count: [g] 16g [3 Feb 2020]
       Genus Trigonum A.K. Mahato & P. Mahato (1994) [monotypic]
      Count: [*] 1s [10 Feb 2020]
         Trigonum indicum A.K. Mahato & P. Mahato
        Count: -