Another 34++ Diplococcus. Diplococcus pneumoniae (klein 1884) weichselbaum 1886. A diplococcus is a round bacterium that typically occurs in the form of two joined cells. The bacterium diplococcus pneumoniae was first described less than a century ago. From wikipedia, the free encyclopedia. Diplococcus - 40 Diplococcus Illustrations Royalty Free Vector Graphics Clip Art Istock Grapelike clusters of cells, staphylococci; The bacterium diplococcus pneumoniae was first described less than a century ago.