New thermophilic Naegleria species (Heterolobosea: Vahlkampfiidae) from Australia and Asia: Allozyme, morphometric and physiological characterisation

Four new thermophilic Naegleria species, capable of growing at 44 degree C, have been recognised in field studies in Australia, southern Asia and the Pacific. Analysis of allozymes at 32 loci and SSUrDNA sequence data show that they are not closely related to N. fowleri or N. lovaniensis, from which they can be differentiated using zymograms for esterase, fructose di-phosphatase, glucose-phosphate isomerase and leucine aminopeptidase. The level of allozyme polymorphism within, and the genetic distance between, the new species is consistent with previously described species in this genus. The new species are non-pathogenic to laboratory mice and have not colonised artificial environments as have N. fowleri and N. lovaniensis. Naegleria carteri sp. n. occurs in tropical Australia, in northern tributaries of the Murray-Darling Basin and in Sri Lanka. N. morganensis sp. n. has been detected only in the Murray-Darling Basin, while N. sturti sp. n. is known from the Murray-Darling Basin and from Bangladesh, Bali and Sri Lanka. N. niuginiensis sp. n. is known from a single isolate from Niugini (New Guinea).