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Genus Micaria

Araneae 5-12-10 01a - Micaria Small Spider - Micaria Ant Mimic Spider - Micaria Micaria - Micaria pulicaria - male Micaria - Micaria pulicaria - female spider - Micaria Utah Spider - Micaria ant-spider - Micaria
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Chelicerata (Chelicerates)
Class Arachnida (Arachnids)
Order Araneae (Spiders)
Infraorder Araneomorphae (True Spiders)
No Taxon (Entelegynes )
Family Gnaphosidae (Ground Spiders)
Genus Micaria
Numbers
41 species in BugGuide's range (North America north of Mexico).
Size
1.3-6.5mm(1)
Identification
"Small active hunters often found in hot dry habitats in full sunlight. Most possess the slender bodies and thin transverse bands of contrasting setae that mimic the ant's segmentation, and shine produced by flattened scale-like iridescent setae. In addition, the spider's front legs may be held in front like antennae, and its nervous walk is clearly reminiscent of an ant's."(2)

Gertsch 1942
M. alberta
- Carapace golden brown with golden hairs, midline with a row of black setae.
- Legs dark with pale stripe.
- Abdomen gray with a pair of white transverse bars above the pedicel and a larger pair at the middle of the dorsum
- irridescent scales some golden but most silvery
M. gosiuta - UT (similar to alberta but has more widely separated posterior eyes)
- Abdomen with basal pair of white patches above the pedicel, and a larger pair at the middle of the dorsum
- iridescent scales evenly golden
M. riggsi - CT, TN
- Carapace dark reddish brown
- Legs orange
- Abdomen black with black iridescent scales
- sides with golden iridescent scales
M. apacheana - AZ & ?
- Carapace yellow brown dusky radiating lines & scattered yellow scales
- Legs yellowish brown, front femora dusky on sides last two with distinct black side bands (creating pale stripes)
- Dorsum of the abdomen with basal and larger median paired white spots
Range
Canadian Micaria - Platnick & Dondale, 1992

More specific range information to be added when resources/time allows.

M. aenea - Holarctic; in America from Alaska to Newfoundland, south into the Rocky Mountains(1)
M. alpina - Holarctic; in America from AK east to Ontario(1)
M. browni - USA; Southeastern US(1)
M. capistrano - USA, Mexico; Known only from southern California and Baja California Norte(1)
M. cimarron - USA; Known only from the type locality in New Mexico(1)
M. coloradensis - USA, Canada; Western North America, from Alaska to Arizona(1)
M. constricta - Holarctic; in America, from Yukon and Northwest Territories south to Arizona, east to Maine and Newfoundland(1)
M. delicatula - USA; Known only from the Eastern Seaboard of the United States(1)
M. deserticola - USA, Mexico; California to Texas, south to Oaxaca, Mexico(1)
M. elizabethae - USA, Candada; Eastern United States and Canada(1)
M. emertoni - North America; Southern Canada to Mexico(1)
M. foxi - USA, Canada; Western North America from Alberta south to New Mexico(1)
M. gertschi - Alberta south to Arizona, east to Nova Scotia and Maine(1)
M. gosiuta - USA, Canada; Oregon and Idaho south to Baja California Sur and Sonora(1)
M. icenoglei - USA; Known only from Riverside Co., California(1)
M. idana - USA, Canada; British Columbia south to California(1)
M. imperiosa - USA, Mexico; Southwestern United States and northern Mexico(1)
M. jeanae - USA, Mexico; Southwestern United States and western Mexico(1)
M. langtry - USA; Known only from type locality in Val Verde Co., Texas(1)
M. lassena - USA; Western United States(1)
M. laticeps - USA, Canada; Alberta to Ontario, south to Utah and Arkansas(1)
M. longipes - USA, Canada; British Columbia to New Brunswick, south to Arizona & Mexico - evidently replaced in the far west of the United States and Mexico by M. gosiuta(1)
M. longispina - USA, Canada; Alberta to Nova Scotia, south to Florida(1)
M. medica - USA, Canada; Known only from Alberta, North Dakota, and Colorado(1)
M. mormon - North America; Alberta and Saskatchewan south to Chihuahua(1)
M. nanella - USA, Mexico; Utah to northeastern Mexico(1)
M. nye - USA, Mexico; Western United States and Mexico(1)
M. otero - USA; Southern California to New Mexico(1)
M. palliditarsa - USA, Mexico; (Spelled "palliditarsus" in Platnick & Shadab 1988, and "palliditarsa" in the World Spider Catalog(3) - no explanation for inconsistency, maybe a typo on WSC?) Southwestern United States and Baja California, Mexico(1)
M. palma - USA; Known only from Florida(1)
M. pasadena - USA, Mexico; Southwestern United States and Northwestern Mexico(1)
M. porta - USA, Mexico; Western United States and northern Mexico(1)
M. pulicaria - Alaska to Newfoundland, south to CA & TX; Widespread in the United States and Canada(1)
M. punctata - USA; Southeastern United States(1)
M. riggsi - South BC to Mass. south to AZ & TN(1)
M. rossica - Holarctic; Western North America, from Alaska south to New Mexico(1)
M. seminola - USA; Southern United States(1)
M. triangulosa - USA; Known only from Texas(1)
M. tripunctata - Alaska to Manitoba(1)
M. utahna - USA; Western United States(1)
M. vinnula - USA; Known only from central and southern Texas(1)
Habitat
Often found in hot dry habitats in full sunlight.(2)
Remarks
In Micaria PER is rarely procurved... usually straight. (Castianeira the PER are slightly to moderately procurved.)

Notes on separating Micaria from Castianeira from Rod Crawford:

Micaria is a gnaphosid although very atypical of the family. It has endites that are crossed by a depression or "valley" between the front and back end of each endite

Micaria has the spinnerets cylindrical (although they are not wide apart like other gnaphosids) while in [members of Corinnidae] the spinnerets would be tapered toward the ends

Micaria: carapace standard pear-shape as in


abdomen covered (or partly so) with translucent iridescent scales color pattern often, though not always, includes chevron-shapes somewhat smaller than Castianeira spinnerets cylindrical and endites with depression (= Gnaphosidae)

Castianeira:
narrowing in front of carapace reduced; narrowing in rear increased

No iridescent scales
Color pattern either strictly transverse or with longitudinal parts, nothing chevron-like somewhat larger than Micaria without gnaphosid family characteristics

Notes from Resources

According to SONA
- all gnaphosids (Micaria) have irregularly shaped PMEs, Castianeira are round
- Castianeira as not having a constricted abdomen

Kaston's how to know the spiders tells the difference between Castianeira and Micaria as
- The well marked thoracic groove in Castianeira.
- Tibiae I & II have two or three pairs of ventral spines in Castianeira

Also, Reiskind (1969), page 164, says the posterior median eyes in Micaria are oval or oblong, which will help to distinguish it from Castianeira (Corinnidae), whose PME are circular.
Print References
Platnick & Shadab 1988. A revision of the American spiders of the genus Micaria (Araneae, Gnaphosidae). American Museum Novitates; no. 2916. http://hdl.handle.net/2246/5164
Works Cited
1.A Revision of the American Spiders of the Genus Micaria (Araneae, Gnaphosidae)
Platnick, Norman I. & Mohammad U. Shadab. 1988. American Museum Novitates, 2916: 1-64.
2.Insects and Arachnids of Canada Part 19: The ground spiders of Canada and Alaska : Araneae: Gnaphosidae
Norman Platnick & Charles Dondale. 1992. Research Branch, Agriculture Canada, Publ. 1875: 1-297.
3.World Spider Catalog