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A Checklist of Manitoba Spiders (Araneae)

with notes on geographic relationships

Introduction


The spider species of Manitoba have never been listed, though various species have been recorded in publications by Criddle (1917) and Aitchison (1978, 1984), or noted incidentally by other authors revising particular genera (Levi, 1973, 1981; Platnick & Shadab, 1975b, 1982; Dondale & Redner, 1978, 1982, 1990; Millidge, 1981a, 1983, 1984, 1987). A checklist, we believe, is a compendium of current biogeographic and related information on all of the known species of a particular taxonomic group within a defined area, demonstrating that group's biodiversity. Such lists may serve to alert researchers to recent range extensions. They may also include taxonomic data such as new synonyms, and give the depositories of the collected specimens which then become known and available to other workers.

Manitoba is regarded as one of the Prairie Provinces, though only the southwestern extremity is occupied by actual prairie (Shay, 1984). Northward, the prairie gives way to aspen parkland, a major transitional zone between prairie and western broad-leafed deciduous forests of Populus, Quercus, Alnus, Acer and Betula (Fig. 1) (Shay, 1984). This is followed by the boreal forest, or circumpolar coniferous forest, characterized by bogs, and which consists of four zones progressing northward: 1) mixed deciduous and coniferous forest; 2) taiga or northern coniferous forest associated with discontinuous or continuous permafrost and with some small stands of aspen and birch along the rivers; 3) taiga-tundra transition, an area with continuous permafrost and poor drainage, typified by scattered black spruce and shrubs; 4) subarctic forest-tundra, a woodland of sparse and stunted trees on continuous permafrost. In the extreme northeast, along the Hudson Bay coast, is an area of arctic tundra, characterized by permafrost and low vegetation (Fig. 1) (Lehmkuhl, 1980; Shay, 1984; Danks & Foottit, 1989).

gif: Map of Vegentation Zones of Manitoba

Figure 1: The vegetation zones of Manitoba (after Shay, 1984).

During the last glaciation, Manitoba was completely covered by an ice sheet; 12,000 years ago the ice began to retreat from the southwest corner of the province, where we now have prairie (Scudder, 1979; Shay, 1984). About 6000 BP the prairie biome extended up to 54°N in the western part of the province, far north of its present northern limit (Scudder, 1979; Shay, 1984), allowing entry of many species from the south. The current ranges of spiders reflect these shifts of biotic communities since that time, with all the flora and fauna being relatively young and spreading from various glacial refugia lying to the east, west, or south, since the last glaciation (Lehmkuhl, 1980).

The following new synonyms are proposed in the list. They are based on our recent research on the Manitoba fauna and are grouped here in brief form for the convenience of cataloguers:

Argenna lorna Chamberlin and Gertsch, 1958
under A.prominula Tullgren, 1948.
Lepthyphantes triramus Chamberlin and Ivie, 1947
under L. duplicatus (Emeton, 1913).
Hilaira algida Hackman, 1954
under Sougambus bostoniensis (Emeton, 1882).
Hilaira aquilonia Hackman, 1954
under Soudinus canaliculatus (Emerton, 1915).
Sciastes ensifer Millidge, 1984
under S. dubius (Hackman, 1954) (new combination).
Tapinocyba exigua Hackman, 1954
under Scirites pectinatus (Emerton, 1911).

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