Redescription of the frog bladder fluke Gorgoderina attenuata from the northern leopard frog, Rana pipiens.

Morphological characters used to differentiate North American bladder flukes, Gorgoderina spp., are problematic and different authors use different morphological characteristics for distinguishing species. More importantly, no type specimens exist for 4 of the 12 North American species infecting anuran and caudatan hosts. A redescription of Gorgoderina attenuata (Stafford, 1902) Stafford, 1905 is based on new collections from 6 species of anurans from Arkansas, Nebraska, New York, and Wisconsin. Morphological comparisons between gravid G. attenuata recovered from bullfrogs and northern leopard frogs indicated statistically significant differences in 11 of 28 morphological characters examined. However, there was overlap among all of these characters, and it is unclear whether these morphological types represent host-induced morphological changes in worm morphology or cryptic species. Based on our findings, we suggest that morphological and molecular data from G. attenuata-like worms recovered from the other 23 definitive hosts reported for G. attenuata need to be collected to resolve this issue.