Peniculida (Peniculid) is an order of ciliates. There are 187 species of Peniculid, in 11 genera and 6 families. It includes groups like Urocentridae, Stokesiidae, and Apofrondoniidae.
Definition: A group of species that exploit the same food resources, and/or use the same feeding or foraging methods. http://en.wikipedia.org/wiki/Guild_(ecology)