Host records and spore morphometrics of Pasteuria penetrans group parasites of nematodes.

Pasteuria penetrans group members were found within or adhering to 52 species of plant parasitic or free living nematodes deposited in collections or resulting from nematological surveyes. A host list is presented which adds four genera and 31 species records not previously reported in association with P. penetrans, as well as eleven new geographic records. The mean spore and central core diameters of the P. penetrans members measured with light microscpy varied continuously from 2.7 to 8 microns and 0.9 to 2.8 microns, respectively. Hierarchical cluster analysis of P. penetrans spore and central core diameters showed four main groups composed of pathotypes parasitic in nematode species from different taxa. The relationship between host taxa and spore morphometrics is discussed.