Trichinella papuae n.sp (Nematoda), a new non-encapsulated species from domestic and sylvatic swine of Papua New Guinea

Encapsulated and non-encapsulated species Of the genus Trichinella are wide spread in sylvatic animals in almost all zoogeographical regions. In sylvat ic animals from Tasmania (Australian region), only the non-encapsulated spe cies Trichinella pseudospiralis: has been reported. Between 1988 and 1998, non-encapsulated larvae of Trichinella were detected in five domestic pigs and six wild boars from a remote area of Papua New Guinea. Morphological, b iological, and molecular studies carried out on one strain isolated from a wild boar in 1997 suggest that these parasites belong to a new species, whi ch has been named Trichinella papuae n.sp. This species can be identified b y the morphology of muscle larvae, which lack a nurse cell in host muscles, and whose total length is one-third greater than that of the other non-enc apsulated Species, T. pseudospiralis. Adults of T. papuae do not cross with adults of the other species and genotypes. Muscle larvae of T. papuae are unable to infect birds, whereas those of T. pseudospiralis do. The expansio n segment V of the large Subunit of the ribosomal DNA differs from that of the other species and genotypes. All df these features allow for the easy i dentification of T. papuae, even in poorly equipped laboratories. The disco very and identification of a second non-encapsulated species in the Austral ian region strongly supports the existence of two evolutionary lines in the genus Trichinella, which differ in terms of the capacity of larvae to indu ce a modification of the muscle cell into a nurse cell. (C) 1999 Australian Society for parasitology Idc. Published by Elsevier Science Ltd. All right s reserved.