Adventures in Spider Misidentification: Endemic in Edmonton?

Tiny (5-6 mm), but colourful Sergiolus columbianus (Emerton, 1917)

The genus Sergiolus Simon, 1891, contains about 26 species of spiders in the family Gnaphosidae (Ground Spiders), many of which are rather colourful and all of which are endemic to the New World. 'Endemic' is one of those funny words that often implies more than it means. Endemic comes from endemos, Greek for 'in people' and when used for a disease where humans are the reservoir, it can more or less mean that. So, malaria is endemic to North America. Or rather it was endemic to North America, because before modern sanitation and insecticides, the malaria protozoans lived in people who lived in North America. It was only after World War II, the spraying of almost 5 million houses with DDT, and the draining and treatment of mosquito breeding areas that malaria was 'eradicated' from the United Sates. Well, not quite eradicated, but transmission became rare and mostly associated with new 'epidemics' around airports and other ports of entry.

One of last summer's many mosquitoes, but not a malaria vector

Before malaria was known to be a disease, caused by protozoans that live in people, and moved from person to person by mosquitoes in the genus Anopheles it was found from Southern Canada and Montana to Massachusetts south (except for the Appalachian region) and in the Central Valley of California. And where it was found was where it was endemic. Malaria is still endemic to many areas of the world. But things change and sometimes for the better.

Today's spider appears to be Sergiolus columbianus (Emerton, 1917). According to Platnick & Dondale (1992), a similar species, Sergiolus montanus (Emerton, 1890) is found from "Southernmost Alaska to New Brunswick, south to South Carolina and to Baja California (Norte), Mexico"  and has been collected in Edmonton. Although not 'in people', in another commonly used sense, that does mean that S. montanus is endemic to an area that includes Edmonton and finding it in our house would be no great surprise. However, the specialists tell us that this is a male of S. columbianus, a more southern spider not known to be endemic to Edmonton. Therefore, we seem to have a new record, but whether we have a transient or a new endemic, only time will tell.


Sources:

Centers For Disease Control and Prevention.  Elimination of Malaria in the United States (1947 — 1951) http://www.cdc.gov/malaria/about/history/elimination_us.html (Accessed 2 December 2012)

Norman Platnick & Charles Dondale. 1992. Insects and Arachnids of Canada Part 19: The ground spiders of Canada and Alaska : Araneae: Gnaphosidae. http://esc-sec.ca/aafcmonographs/insects_and_arachnids_part_19.pdf