Lr. Smales, HETERAKIS FIELDING N-SP (NEMATODA, HETERAKOIDEA) FROM THE AUSTRALIAN WATER-RAT, WITH A REVIEW OF HETERAKIDS OCCURRING IN MAMMALS, Systematic parasitology, 35(2), 1996, pp. 127-132
Heterakis fielding n. sp. is described from Hydromys chrysogaster. It
can be distinguished from Heterakis spumosa, the species it most close
ly resembles, in that both males and females are much smaller (4.4 and
5.1 mm, versus 9 and 13 mm, respectively for Australian specimens) an
d males have shorter tails (178 versus 345 mu m) with 9 pairs of cauda
l papillae compared with 10 pairs for H. spumosa. Of the species of He
terakis previously described from mammals three, H. spalacis, H. macro
spiculum and H. verrucosa, are presently considered incertae sedis, a
fourth has been referred to the genus Gireterakis and a fifth, H. pand
ei, described almost simultaneously with H. yamaguti, is considered to
be synonymous with it. The remaining species are H. spumosa, H. ingli
si and H. yamaguti. The presence of these four species in mammalian ho
sts, when all other representatives of the genus occur in grain-eating
birds, cannot be explained at present.