Synonyms and other taxonomic changes
Chiracanthium is considered by the
World Spider Catalog as "an unjustified emendation."
This genus has previously been placed in Clubionidae, Miturgidae, and Eutichuridae.
Explanation of Names
From Greek, meaning "hand spinelet", referring to the backwardly directed process on the cymbium of the male palp.
(1)Numbers
There are 2 species in BugGuide's region.
Identification
"Cheiracanthium are distinguished from the closely related species of Clubiona by lacking a conspicuous dorsal groove in the midline of the carapace, the lack of a cluster of long curved erect setae at the anterior end of the abdomen, by having the first pair of legs the longest, and by having a long, pointed spur extending back from the cymbium over the tibia. Species of Cheiracanthium are also characterized by having relatively thinner legs and more robust bodies than Clubiona." From article by Jørgen Lissner (link?).
The genitalia are the best way to identify the two species, as the two species are similar in appearance. C. inclusum is generally found outdoors while C. mildei is typically found indoors, but that is not 100% reliable.
Epigyna:
C. inclusum 
C. mildei
Palp:
C. inclusum
C. mildei
The dorsal tibial apophysis on the palp of C. mildei will likely be the most helpful feature when looking at typical user-submitted photos.
Range
C. inclusum is indigenous to much of the United States (except the northernmost states), while C. mildei, an introduced species from Europe, was found throughout much of the Northeast as of 1978. It is likely that C. mildei has substantially increased its range since that time. (1)
Remarks
Being Bitten:
Some species are thought to be slightly dangerous. However, this may not be true. See articles:
~
www.ajtmh.org. - VERIFIED BITES BY YELLOW SAC SPIDERS (GENUS CHEIRACANTHIUM) IN THE UNITED STATES AND AUSTRALIA: WHERE IS THE NECROSIS?
~
www.jabfm.org - Spider Myths and a Case of a Bite by a Yellow Sac Spider
Internet References
World Spider Catalog (2014). World Spider Catalog. Natural History Museum Bern, online at http://wsc.nmbe.ch, version 15.5, accessed on 11/11/2014
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