The Protargol staining technique (Zagon and Small, 1970) was run following the procedure described in Utz and Coats (2005), and diagnostic characteristics of Z.
Live observations and Protargol staining revealed that four species in the genus Zoothamnium (two of them tentatively identified as Z.
Zoothamnium intermedium found as epibiont on Chesapeake Bay copepods is an example of obligate epibiont, since it failed to attach to glass surfaces in the laboratory (Utz, 2003) and to glass cover-slips in the field, as was demonstrated by live and Protargol staining observations of peritrichs attached to cover-slips sampled from nature.
Gross (1986), in a study characterizing species of Zoothamnium from the Patuxent River, a subestuary of the Chesapeake Bay using the morphological characters revealed by the Protargol staining technique, also found four species of this genus colonizing slides, but none of them with Z.
Protargol silver staining as a method for the comparative study of five species in the genus Zoothamnium Boryde St.