Neomysis americana (Crustacea: Mysidacea) as an Intermediate Host for Sealworm, Pseudoterranova decipiens (Nematoda: Ascaridoidea), and Spirurid Nematodes (Acuarioidea)

Amphipods (Gammarus oceanicus) and mysids (Neomysis americana) were collected from three brackish ponds on Sable Island, 290 km east of Halifax, Nova Scotia. Thirteen nematodes were recovered from 3950 mysids subjected to enzymatic digestion. Four of the nematodes were identified as larval sealworm (Pseudoterranova decipiens). The remaining nematodes belong to two species: Paracuaria adunca and Cosmocephalus obvelatus (Acuarioidea). This is the first record of N. americana as an intermediate host for P. decipiens. It is also the first report of a mysid as intermediate host for either of the acuarioid nematodes and the first evidence of these two nematodes undergoing part of their life cycles in brackish or marine conditions. No nematodes were observed in 2364 amphipods or 1462 mysids examined microscopically, but unidentified metacercariae were found in 1.9% of the amphipods.