A morphological and genetic review of the Pardosa groenlandica species complex (Araneae: Lycosidae)

Abstract

The Pardosa groenlandica species complex comprises seven recognized species, P. groenlandica (Thorell 1872), P. dromaea (Thorell 1877), P. tristis (Thorell 1877), P. prosaica Chamberlin and Ivie 1947, P. bucklei Kronestedt 1975, P. albomaculata Emerton 1885, and P. lowriei Kronestedt 1975. These species have overlapping distributions, creating sympatric occurrences with at least one other member of the complex. They can be found in Greenland, throughout Canada, and occur in the United States from the Rocky Mountains to the Pacific coast, through Alaska, and as far as eastern Siberia. These species' genitalia, which bear the primary diagnostic characters, are very similar and show large amounts of within-species and within-population variation. Because of this, they have seen various levels of taxonomic splitting and lumping from one species to the presently recognized seven. I evaluated the utility of the existing morphological diagnostic characters which, if geography is ignored, successfully diagnose only four species (P. albomaculata, P. lowriei, and P. bucklei, with the remaining species synonymized under P. groenlandica). Additionally, I sequenced five genes, two mitochondria) (COI & NDI), and three nuclear genes (ITS 1, 5.8S, and ITS2) of 144 specimens, to help clarify the taxonomy of the species complex. All seven species showed some level of polyphyly or paraphyly in their gene trees. A population genetics analysis of P. groenlandica and P. tristis from Colorado populations failed to find molecular divergence between the populations, raising questions about P. groenlandica occurring in Colorado, and/or the validity of P. tristis. These results question the value of using this genetic dataset to test species delineated using traditional taxonomic methods in the groenlandica species complex of the genus Pardosa. Reconciliation is likely only when genetic markers are studied that match the timing and rate of the observed phenotypic changes.