Potential new species of pseudaliid lung nematode (Metastrongyloidea) from two stranded neonatal orcas (Orcinus orca) characterised by ITS-2 and COI sequences

Knowledge about parasite species of orcas, their prevalence and impact on
the health status is scarce. Only two records of lungworm infections in
orca exist from male neonatal orcas stranded in Germany and Norway. The
nematodes were identified as Halocercus sp. (Pseudaliidae), which have
been described in the respiratory tract of multiple odontocete species,
but morphological identification to species level remained impossible due
to the fragile structure and ambiguous morphological features. Pseudaliid
nematodes (Metastrongyloidea) are specific to the respiratory tract of
toothed whales and are hypothesized to have become almost extinct in
terrestrial mammals. Severe lungworm infections can cause secondary
bacterial infections and bronchopneumonia and are a common cause of
mortality in odontocetes. DNA isolations and subsequent sequencing of the
rDNA ITS-2 and mtDNA COI revealed nucleotide differences between
previously described Halocercus species from common dolphin (H.
delphini) and harbour porpoises (H. invaginatus) that were comparatively
analysed, pointing towards a potentially new species of pseudaliid
lungworm in orcas. New COI sequences of six additional metastrongyloid
lungworms of seals and porpoises were derived to elucidate phylogenetic
relationships and differences between nine species of Metastrongyloidea.