Morphological and molecular characterisation of Spirinia antipodea Leduc n. sp. (Nematoda: Desmodoridae), a cryptic species related to S. parasitifera, from the coast of New Zealand

Abstract

SummarySpirinia parasitiferais a common nematode species recorded from coastal habitats of the White, North and Barents Seas, the Northwest Atlantic, the Maldives and Australia, and exhibits a high degree of variability in some morphological characters. For these reasons it has been suggested thatS. parasitiferais a species complex comprised of several distinct but potentially cryptic species. However, no study has yet combined molecular and morphological approaches to verify this assertion. Here, we describeS. antipodean. sp., a species morphologically very similar toS. parasitifera, from the coast of New Zealand.Spirinia antipodean. sp. differs from the original description ofS. parasitiferaas well as subsequent descriptions by other authors in at least one body dimension, but no single trait differs consistently between the New Zealand specimens and all descriptions ofS. parasitifera. Phylogenetic analyses showed that the new species is distinct from other species of the genus, includingS. parasitiferaspecimens sampled near the type locality. TheS. antipodean. sp. SSU sequence differed from otherSpiriniasequence by 2.1-5.3%, whilst D2-D3 of LSU sequences differed by 12.5-18.9%. The consensus SSU tree also recovered three distinctS. parasitiferaclades, which provides support for the existence of a species complex. Because it is not possible to determine whether the variability in morphological characters observed among descriptions ofS. parasitiferais intra- or interspecific, and therefore to determine which trait can reliably be used to differentiate betweenS. antipodean. sp. andS. parasitifera, the new species is best differentiated fromS. parasitiferaand other closely related species based on SSU sequences rather than morphological characters.