First record of larvae of Spiroxys (Nematoda: Gnathostomatidae) parasitizing fishes in stream of the Caatinga domain.

The present study is the first report of Spiroxys larvae parasitizing stomach and intestine of three fish species in stream of Caatinga domain, Northeast, Brazil. A total of 120 fish specimens, 40 of Astyanax bimaculatus, 40 of Hoplias malabaricus, and 40 of Hoplosternum littorale were examined for nematodes. A total of 633 specimens of Spiroxys larvae were recovered for the three fish species: 227 in A. bimaculatus (prevalence (%) = 48; mean abundance = 5.78 ± 1.78 (range = 0-70); and mean intensity = 11.95 ± 2.7 (range = 2-70)), 176 in H. malabaricus (prevalence (%) = 42.5; mean abundance = 4.40 ± 1.55 (range = 0-53); and mean intensity = 10.35 ± 2.38 (range = 2-53)) and 230 in H. littorale (prevalence (%) = 42.5; mean abundance = 5.75 ± 1.98 (range = 0-52); and mean intensity = 13.53 ± 3.04 (range = 1-52)). This study expands the range of the geographic distribution of nematodes of the genus Spiroxys and increase the list of hosts, as well as contributing to the knowledge of fish parasites biodiversity in Caatinga domain.