Phylogenetic analysis has found that polyacanthocephala represents a distinct class of acanthocephalans.

Samples were found in the liver of Tilapia and Orechromis and free in the body cavity in Micropterus[6] It is the newest P. macrorhynchus infect South American caimans.

[4] Pirarucu collected in August 2004 from Araguaia River were found to have high prevalence values of P. rhopalorhynchus in their intestines.

[7] Cystacanths of P. rhopalorhynchus also have been found in the viscera of Hoplias malabaricus from Moca Vie River, Las Palquitas, Bolivia.

Cyscanaths had: The number of proboscis hook rows was 16–18 posteriorly gradually decreasing in size.