Resurrection and redescription of Varestrongylus alces (Nematoda; Protostrongylidae), a lungworm of the Eurasian moose (Alces alces), with report on associated pathology
Verocai, Guilherme G.; Hoberg, Eric P.; Vikøren, Turid; Handeland, Kjell; Ytrehus, Bjørnar; Rezansoff, Andrew M.; Davidson, Rebecca K.; Gilleard, John S.; Kutz, Susan J.
Peer reviewed, Journal article
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Date
2014Metadata
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Abstract
Varestrongylus alces, a lungworm in Eurasian moose from Europe has been considered a
junior synonym of Varestrongylus capreoli, in European roe deer, due to a poorly detailed
morphological description and the absence of a type-series.
Methods
Specimens used in the redescription were collected from lesions in the lungs of Eurasian
moose, from Vestby, Norway. Specimens were described based on comparative morphology
and integrated approaches. Molecular identification was based on PCR, cloning and
sequencing of the ITS-2 region of the nuclear ribosomal DNA. Phylogenetic analysis
compared V. alces ITS-2 sequences to these of other Varestrongylus species and other
protostrongylids.
Results
Varestrongylus alces is resurrected for protostrongylid nematodes of Eurasian moose from
Europe. Varestrongylus alces causes firm nodular lesions that are clearly differentiated from
the adjacent lung tissue. Histologically, lesions are restricted to the parenchyma with adult,
egg and larval parasites surrounded by multinucleated giant cells, macrophages, eosinophilic
granulocytes, lymphocytes. The species is valid and distinct from others referred to
Varestrongylus, and should be separated from V. capreoli. Morphologically, V. alces can be
distinguished from other species by characters in the males that include a distally bifurcated
gubernaculum, arched denticulate crura, spicules that are equal in length and relatively short,
and a dorsal ray that is elongate and bifurcated. Females have a well-developed provagina,
and are very similar to those of V. capreoli. Morphometrics of first-stage larvae largely
overlap with those of other Varestrongylus. Sequences of the ITS-2 region strongly support
mutual independence of V. alces, V. cf. capreoli, and the yet undescribed species of
Varestrongylus from North American ungulates. These three taxa form a well-supported
crown-clade as the putative sister of V. alpenae. The association of V. alces and Alces or its
ancestors is discussed in light of host and parasite phylogeny and host historical
biogeography.
Varestrongylus alces is a valid species, and should be considered distinct from V. capreoli.
Phylogenetic relationships among Varestrongylus spp. from Eurasia and North America are
complex and consistent with faunal assembly involving recurrent events of geographic
expansion, host switching and subsequent speciation.
Cervidae, Cryptic species, Historical biogeography, ITS-2, Metastrongyloidea, Parasite
biodiversity, Varestrongylinae, Varestrongylus capreoli, Verminous pneumonia