Polyacanthorhynchus
Introduction '''Polyacanthorhynchidae''' is a family of parasitic worms from the (phylum Acanthocephala). It contains a single genus '''''Polyacanthorhynchus'''''.
Taxonomy Phylogenetic analysis has found that polyacanthocephala represents a distinct class of acanthocephalans.
Species There are four species in the genus '''Polyacanthorhynchus'''. * '''''Polyacanthorhynchus caballeroi''''' Diaz-ungria and Rodrigo, 1960The complete genome of the mitochondria has been determined. ''P. caballeroi'' infect South American caimans. * '''''Polyacanthorhynchus echiyensis''''' * '''''Polyacanthorhynchus kenyensis''''' Schmidt and Canaris, 1967''P. kenyensis'' has been found infecting three freshwater teleosts: the Blue spotted tilapia (''Oreochromis leucostictus''), the Redbelly tilapia (''Tilapia zillii''), and the Largemouth bass (''Micropterus salmoidein'') in Lake Naivasha, Kenya. Samples were found in the liver of ''Tilapia'' and ''Orechromis'' and free in the body cavity in ''Micropterus'' It is the newest	 * '''''Polyacanthorhynchus macrorhynchus''''' (Diesing, 1856)''P. macrorhynchus'' infect South American caimans. * '''''Polyacanthorhynchus nigerianus''''' * '''''Polyacanthorhynchus rhopalorhynchus''''' (Diesing, 1851)Pirarucu collected in August 2004 from Araguaia River were found to have high prevalence values of P. rhopalorhynchus in their intestines. Cystacanths of ''P. rhopalorhynchus'' also have been found in the viscera of ''Hoplias malabaricus'' from Moca Vie River, Las Palquitas, Bolivia. Cystacanths were not deeply embedded in liver tissue but in a collagenous connective tissue capsule surrounded and attached to the liver surface. Necrosis of hepatocytes and subsequentinflammatory response were observed near encapsulated ''P. rhopalorhynchus''. ''P. rhopalorhynchus'' infect South American caimans. Cyscanaths had: The number of proboscis hook rows was 16–18 posteriorly gradually decreasing in size. There are 8–10 circles of anterior cuticular trunk spines with about 34–40 minute spines each. Lemnisci not pronounced. Male cystacanths were 1.985–2.978 mm long by 397–662 wide significantly smaller than the size of adult males of 40–55 mm long. Females are larger with female cystacanths were 2.445–2.813 mm long by 430–496 wide significantly smaller than the size of adult males of 50–70 mm long. Male cystacanth proboscis (1.430–1.690 mm long by 169–208 wide) were smaller than female cystacanth proboscis (1.196–1.430 mm long by 169–208 wide). Male cystacanth proboscis receptacle (0.611–1.105 mm long by 130–195 wide) were also smaller than the female cystacanth proboscis receptacle (780–845 long by 156–195 wide).
Hosts ''Polyacanthorhynchus '' species parasitize fish and caimans.File:Oreochromis leucostictus Lake Malimbe.jpg|alt=Blue spotted tilapia held in hands|The Blue spotted tilapia is one of the hosts of ''P. kenyensis''File:St. Peter's Fish.jpg|alt=Redbelly tilapia swimming in an aquarium|The Redbelly tilapia is one of the hosts of ''P. kenyensis''File:1351 largemouth bass (Micropterus salmoides) 300 dpi.jpg|alt=Largemouth bass underwater in a natural habitat|The Largemouth bass is one of the hosts of ''P. kenyensis''File:Hoplias malabaricus1.jpg|alt=''Hoplias malabaricus'' displayed in a box|''Hoplias malabaricus'' is one of the hosts of ''P. rhopalorhynchus''
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