Phylogenetic relationships among Hepatozoon species from snakes, frogs andmosquitoes of Ontario, Canada, determined by ITS-1 nucleotide sequences and life-cycle, morphological and developmental characteristics

The molecular biological characteristics of Hepatozoon species infecting Va rious species of snakes, frogs and mosquitoes were investigated by determin ing the nucleotide sequences of the first internal transcribed spacer regio n. A phylogenetic analysis was performed on seven isolates of Hepatozoon in fecting snakes, including Hepatozoon sipedon and four morphologically simil ar but not identical forms, and two isolates of Hepatozoon catesbianae infe cting Green frogs (Rana clamitans melanota). This analysis, which utilised data from first internal transcribed spacer nucleotide sequences, morpholog ical and morphometric features of gamonts, oocysts and sporocysts, and prev iously determined life-cycle and host-specificity characteristics, revealed that H. sipedon is a polymorphic species with a wide host and geographic r ange. Four synapomorphies, including two nucleotide substitutions and two m orphological character state changes, supported a monophyletic group of six isolates of H. sipedon from the central region of Ontario which was the si ster group for an isolate (HW1) from the southern part of the province. Bas ed on the results of this study, an evaluation of which criteria are useful for describing species of Hepatozoon is presented, with the intent of curt ailing the practice of naming species based on morphological features of ga monts or on incomplete life-cycle data. (C) 1999 Australian Society for Par asitology. Published by Elsevier Science Ltd. All rights reserved.