Acta Parasitologica, Vol. 52, No. 2, 2007, 146–150. DOI: 10.2478/s11686-007-0022-3 José L. Luque1, Liza M. Bannock2, Clément Lagrue2 and Robert Poulin2* –
Larval Hysterothylacium sp. (Nematoda, Anisakidae) and trematode metacercariae from the amphipod Paracorophium excavatum (Corophiidae) in New Zealand
1Departamento de Parasitologia Animal, Universidade Federal Rural do Rio de Janeiro, Caixa Postal 74.508, CEP 23851-970, Seropédica, RJ, Brasil; 2Department of Zoology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
*Corresponding author: obert.poulin@stonebow.otago.ac.nz
ABSTRACT
Previously undescribed fourth-stage larvae of anisakid nematodes were found in the haemocoel of the amphipod
Paracorophium excavatum (Thomson, 1884) (Corophiidae) in New Zealand. Morphological examination by light microscopy
showed that the worms belonged to a species of Hysterothylacium Ward et Magath, 1917, based on several characters including
the presence of interlabia, the location of the excretory pore posterior to the nerve ring, and the characteristics of the intestinal
caecum and ventricular appendix. Interestingly, several male specimens showed precocious sexual development. This is
the first record of fourth larval stage and precocious adult male specimens of Hysterothylacium in an invertebrate host, as well
as the first record of anisakid larvae in New Zealand crustaceans. In addition, metacercariae of two trematode species,
Coitocaecum parvum and Microphallus sp., are recorded for the first time from the amphipod P. excavatum.
KEY WORDS: Anisakid larvae, Hysterothylacium, metacercariae, Coitocaecum, Microphallus, amphipods, Paracorophium, New Zealand