The role of voucher specimens in validating faunistic and ecological research

Deposition of vouchers permits long term studies

McCorquodale (2001) used old voucher specimens deposited in a variety of regional insect collections to re-assess the presence of several species of Cerambycidae (Coleoptera) in Ontario. Because voucher specimens from studies by early authors were available for identification, McCorquodale was able to record several new species for Ontario.

In a similar, but larger scale study, Favret and DeWalt (2002) used newly assembled electronic databases of holdings of Ephemeroptera and Plecoptera in the Illinois Natural History Survey collection to assess faunal changes (range expansions, range reductions, changes in abundance) in those orders over the course of the 20th Century in Illinois.

Resh (1976) used old collection data to confirm (and correct) species identifications of caddisflies (Trichoptera) collected in Ohio and Illinois several years previously as well as documenting changes in the fauna resulting from habitat degradation over a 50-year period (see also Resh and Unzicker (1975)).

Leibherr and Song (2002) assessed carabid beetle (Coleoptera) diversity in bogs and marshes in New York, comparing their field data to specimens collected at least 75 years earlier in order to assess change in the community over time.

In addition to these specific examples other authors (e.g., Shaffer et al. 1998, Ponder et al. 2001) have recognized the general value of specimens housed in natural history collections in assessing changes in species distributions and abundance over time.

Unpublished data on selected groups of Canadian grassland arthropods provide the potential for assessing long-term change in those habitats. Manitoba entomologist Norman Criddle collected large numbers of ground beetles (Coleoptera: Carabidae) in grassland habitats in Aweme, Manitoba in the early part of the 20th Century. Criddle kept extensive and exhaustive field notes which survive largely intact, and he deposited specimens from his field studies in a number of insect collections, notably those at the University of Manitoba and the Canadian National Collection of Insects, although Criddle’s Coleoptera are found almost worldwide in collections as a result of exchanges (R.E. Roughley, D. Pollock pers. comm.). Examination of those specimens in museums allows current workers to confirm the identity of Criddle’s material against current species limits and facilitates follow-up inventory studies of carabid diversity at the Aweme site almost 100 years later.

Criddle also collected large numbers of acalyptrate Diptera (especially Chloropidae and Agromyzidae) in southern Manitoba grasslands during the summers of 1915-1916 and sent the samples to the dipterist J.M. Aldrich in Washington DC, who identified the specimens and deposited them in the Smithsonian Institution collection. Because both Criddle and Aldrich made copious notes on these specimens, because later workers retained these notes (now housed in the University of Manitoba and the Lyman Entomological Museum), and because Aldrich deposited voucher specimens, cross-referenced to the field notes, it would be a relatively simple matter today to confirm Aldrich’s species concepts, generate an updated species list and replicate Criddle’s survey after a century of change in the habitat.

Page updated on Feb 23, 2014