MORPHO-TAXONOMY OF THE FAMILY MERISMOPEDIACEAE, CHROOCOCCALES, CYANOPROCARYOTE

Among unicellular and colonial Cyanobacteria the family Merismopediaceae is characterized by having solitary cells or one layered flat or spherical or irregular colonies with or without central mucilaginous stands or stalks. Cells characteristically, divide in two planes and they are at right angle to each other. Further, daughter cells reach to original size and shape before next division takes place. At the global level, there are about 15 genera and 190 species in the family. The well established genera of the family are Synechocystis, Aphanocapsa, Merismopedia, Coelosphaerium and Gomphosphaeria. The genus Microcrocis appears to be quite distinct in having elongated cells, and longer axis perpendicular to the plane of the colony but is of rare occurrence. Validity of certain other genera remains doubtful and need critical culture studies. The genera like Pannus, Mantellum, Cyanotetras, Coccopedia of sub-family Merismopedioideae appear to be the stages of Merismopedia or Coelosphaerium. Certain other genera like Coelomoron, Coelosphaeriopsis, Snowella, Woronichinia and Siphonosphaera of sub-family Gomphosphaerioideae may also be the growth stages of Coelosphaerium or Gomphosphaeria.