Genus Micaria
The genus Micaria consists of ant-like species that belongs to the ground spider family (Gnaphosidae). In appearance, they are more likely to be confused with the genus Castianeira in the family Corinnidae than they are with fellow ground spiders (they both belonged to the family Clubionidae at one point). Jumping spiders in the genus Tutelina and Synageles have some superficial similarities, but eye arrangement and behavior can quickly rule them out.
Members of this genus move quickly (bordering on frantic). Just think, "Fast-moving Ant" and you will have a good idea what to expect. Many species seem to prefer upland, dry habitats but I have found M. pulicaria running with Pardosa wolf spiders at the edge of a wetland. One of the characteristics of these spiders is the flat, iridescent scales that cover their abdomen and sometimes the carapace. It can give them a very bright (and sometimes colorful) appearance.
In Minnesota there are 5 species of Micaria that are known to occur in the state and an additional 3 species that are listed as hypothetical. They are poorly represented in collections and very little is known about their distribution in the state.
M. pulicaria has the best known distribution in the state (12 counties). It is known from Freeborn and Blue Earth Counties in the south to Koochiching and Roseau Counties in the north which suggests it may be found statewide. https://www.inaturalist.org/observations/25522283
M. longipes may well occur across the state but is only known from Blue Earth, Wabasha, Ramsey, Itasca and St. Louis Counties. https://www.inaturalist.org/observations/92601891
M. gertschi is known from Blue Earth, Hennepin, Ramsey, Renville, and Rock Counties. I have only found specimens in a rock garden on the campus of Bethany Lutheran College. https://www.inaturalist.org/observations/5219349
M. riggsi is only known from Clay County.
M. rossica is only known from Itasca County.
The three species that are listed as hypothetical are: M. aenea, M. emertoni, and M. longispina.
Keep an eye out for these spiders in the coming summer.
Happy Spidering!
Comments
Very interesting especially for this gal who doesn’t care for bugs — so buggy-observations (especially spiders) is a big step for me!
My question is procedural, perhaps, and that is: it appears from your writings that there’s only one of these spiders in Hennepin. Is that correct? Or are you saying ‘reported via iNaturalist’? If only one of those spiders is reported in Hennepin, what is the explanation that there are some in Ramsey, but not Hennepin — which to this human seems so close to one another? As always, thank you for these! I’m learning!
@jldm The summary of distributions I provided are based on the records in the literature, museum specimens and personal collecting efforts (which goes beyond observations here on iNaturalist). A species that is found in Ramsey County will likely be found in Hennepin County as well due to their proximity (there are just no records from that county at this time). One of the purposes of the Spiders of Minnesota Project is to try and add additional data points to improve our understanding of species distribution in Minnesota.
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