The Misumenini
I do not typically worry about taxa between family and genus. But in this instance, I am thankful for the catch-all category of Tribe Misumenini which includes all of Minnesota's flower crab spiders. As the name suggests, these spiders often lie in ambush in flowers (but are not the only crab spiders to do so--Xysticus!). They are predominantly yellow or white but may have pink/red or green on them as well. This enables them to remain camouflaged as they wait patiently for prey to visit the flower.
These species are sexually dimorphic (appearance differs based on sex). Most noticeably, females are larger than their male counterparts. These species mature in early summer and adults can typically be found into September. There are four genera and six species of flower crabs in Minnesota.
Misumena vatia or Goldenrod Crab Spider is the most commonly encountered flower crab in Minnesota. Females can be yellow or white (and can vary that based on the flower they are trying to blend in with) with pink streaks on the sides of the abdomen that sometimes connect at the anterior of the abdomen (though the pink is sometimes not present). Legs of the females are typically yellow or white and lack any banding. Males have dark red-brown coloration on the lateral portions of the carapace. The first two pairs of legs are also generally dark red-brown with sparse, thick yellow bands (the latter pair of legs are pale and unmarked). The abdomen is typically pale with dark red-brown lateral edges and two irregularly-shaped red-brown marks toward the posterior half. All the anterior eyes are about the same size in this species.
Female: https://www.inaturalist.org/observations/53700956
Male: https://www.inaturalist.org/observations/128361558
Misumenoides formosipes or White-banded Crab Spider is most easily identified by the white (sometimes yellow) transverse band below the eyes. Females can be unmarked, weakly marked, or strongly marked with red. The dorsal pattern (if present) is a dark V that becomes more broken up as it passes posteriorly; sometimes there are red longitudinal marks on the sides as well. The legs of females may or may not have bands. The carapace pattern of males is similar to M. vatia and the first two pairs of legs are typically dark as well (but lack the yellow bands of M. vatia) with the rear pairs being pale. The male abdomen is unmarked and ranges in color from yellow to dark orange-red. All the anterior eyes are about the same size in this species and there is a raised ridge between the anterior eye row and the posterior eye row.
The typical white band below the eyes: https://www.inaturalist.org/observations/93999675
Strongly marked female: https://www.inaturalist.org/observations/31195646
Weakly marked female: https://www.inaturalist.org/observations/179894729
Unmarked female: https://www.inaturalist.org/observations/126401133
Male: https://www.inaturalist.org/observations/5434037
Misumessus oblongus or American Green Crab Spider can resemble a more delicate, less robust version of Misumena vatia. Females are often pale yellow to green and can have pink lateral marks on the abdomen like M. vatia, but the abdomen can also be unmarked. The anterior lateral eyes are noticeably larger than the anterior median eyes unlike M. vatia's which has eyes that are all about the same size. Males are easy to distinguish from other Misumenini. They body is typically pale green overall without markings and the first two pairs of legs have five reddish bands of various thickness while the rear pairs are largely unmarked.
Female: https://www.inaturalist.org/observations/224181411
Male: https://www.inaturalist.org/observations/6625249
The genus Mecaphesa is the most problematic of the flower crabs. There are three species known to occur in Minnesota. Like M. vatia, their color ranges from yellow to white but these spiders typically show a hairier body than other Misumenini. The abdomen pattern is variable within species with some individuals showing a bold pattern and others showing a muddled pattern to very little pattern at all. The posterior lateral eyes are on tubercles and point sideways/backwards. Identifying members of this genus to species from a picture should be done with caution and examination of the genitalia is the most reliable way to distinguish between them at this time (easier with the males than females). I am not going to use this space to get into differences in genitalia so I'll just include a few notes on each species below.
Mecaphesa carletonica or Northeastern Flower Crab Spider reaches its western distribution limit in Minnesota. This is likely the rarest member of the genus in Minnesota and is only known from a museum specimen collected in Hennepin County. It is superficially very similar to M. asperata and the largest reason for caution when identifying members of this genus.
Voucher female 1: https://bugguide.net/node/view/937371
Voucher female 2: https://www.inaturalist.org/observations/142318422
Mecaphesa asperata or Northern Crab Spider is found throughout the state. I think this is the most common member of the genus in Minnesota, but proving that statement true would require a lot more collection/dissection on my part. See notes on distinguishing males of this species from males of M. celer below.
Voucher female 1: https://www.inaturalist.org/observations/227815065
Voucher female 2: https://www.inaturalist.org/observations/227815063
Voucher male: https://www.inaturalist.org/observations/226706766
Mecaphesa celer or Swift Crab Spider is also found throughout the state. The males of this species are more readily identified than any other Mecaphesa individual. The carapace is often pale green with two smudgy green longitudinal bands bordering a pale median area. The abdomen is pale green to white with two types of black spotting. The posterior half has two rows of 4 larger black spots equidistant from each other; the anterior half has smaller black spots that are separated by variable distances. The M. asperata males typically have reddish patterns on the abdomen or muddled, indistinct rows of spots on the posterior half.
Voucher female: https://www.inaturalist.org/observations/126403621
Voucher male: https://www.inaturalist.org/observations/5434099
Happy spidering!
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