Mecaphesa asperata (Northern Crab Spider) – quick notes on geographic range and identification
For reasons unknown to me, the crab spider species Mecaphesa asperata (formerly known as Misumenops asperatus, common name Northern Crab Spider) has become the AI/automated suggestion of choice for crab spider images in the western US, the area where I normally review spider observations. Although this species is known to be widespread in North America, to my knowledge it has not been accurately documented from California and it's unclear to me if it is known from Arizona, Oregon or Washington state. In addition, with only one exception I am aware of, crab spiders in the genus Mecaphesa are difficult or impossible to ID to species without examining the genitalia of an adult spider, usually a collected specimen.
This is all to say that I encourage everyone NOT to accept the automated suggestion of M. asperata for crab spiders photographed in California and neighboring states and, if folks feel comfortable, to disagree with IDs of this spider in that area. I've included more information below.
From Dondale and Redner 1978 - Crab Spiders of Canada and Alaska:
Range: “New Mexico to Florida, northward to British Columbia, Quebec, and Massachusetts".
ID: Discuss genitalia, no comments on coloration being diagnostic. Collected from foliage and blossoms.
From Gertsch 1939:
Range: “United States and Canada. The species become increasingly rarer toward the south and- at the present time there seem to be no authentic records from Mexico or the West Indies”. Gertsch 1939 does indicate a single record of a male collected from Claremont, California – BUT see below.
From Schick 1965:
“Asperatus group: At least three species of this group occur in the United States, M. asperatus (Hentz), M. verityi, new species, and M. devius Gertsch, the last two from California. Asperatus is cited from California from a single record in the 1939 revision of Gertsch (Claremont, Los Angeles County), but this is a doubtful record". (note: Schick produced a detailed monograph on the crab spiders of California in 1965 and probably understood the ID and ranges of these spiders in CA better than anyone before or since that time).
M. asperata/asperatus not listed in the Johnson/Lew checklist found here:
https://www.ocf.berkeley.edu/~stevelew/soc.html
M. asperata/asperatus is not listed in Rod Crawford’s 1988 Annotated Checklist of the Spiders of Washington
