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Species Sergiolus montanus

black and white ground spider - Sergiolus montanus - male Adult female - Sergiolus montanus - female Sergiolus? - Sergiolus montanus - female Sergiolus montanus - female Mouse Spider? Fantastic abdominal markings. - Sergiolus montanus Gnaphosid - Sergiolus montanus Sergiolus sp. (Ground spider) - Sergiolus montanus Sergiolus sp. (Ground spider) - Sergiolus montanus
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Chelicerata (Chelicerates)
Class Arachnida (Arachnids)
Order Araneae (Spiders)
Infraorder Araneomorphae (True Spiders)
No Taxon (Entelegynae)
Family Gnaphosidae (Ground Spiders)
Genus Sergiolus
Species montanus (Sergiolus montanus)
Synonyms and other taxonomic changes
Males: ~4.9 mm(1)
Females: ~6.9 mm(1)
There appears to be quite a bit of variation in the abdominal patterning of this species. A microscopic exam of the spider's genitalia is typically necessary for accurate identification.

"...specimens of the widespread species S. montanus are usually colored much like those of northern S. bicolor, but individuals with a light cephalothorax and appendages and more extensive light markings on the abdominal dorsum are known from Oregon, Idaho, Utah, Colorado, and California (where they become proportionately more common toward the southern end of the state)." (Platnick & Shadab 1981)

Examples from California (female)/Washington (male/female)/Alaska (female):


Southernmost Alaska to New Brunswick, south to South Carolina and to Baja California (Norte), Mexico.(1)
"Specimens have been collected under rocks, reeds, bark, driftwood on beaches, dry cow patties, in bogs, climax chaparral...and associated with jack pine, ponderosa pine, scrub oak, aspen, and sage, in and around buildings and in stabilized talus at elevations up to 10,200 feet."(1)
Mature males: February to October(1)
Mature females: year-round
See Also
Very similar to other species of Sergiolus; a microscopic exam of genitalia is required for clear identification.
Print References
~ Platnick, N. I. & C. D. Dondale, 1992. The Insects and Arachnids of Canada, Part 19. The ground spiders of Canada and Alaska (Araneae: Gnaphosidae). Research Branch, Agriculture Canada, Publ. 1875: 1-297, PAGE 233. (free download of full monograph from here:

~Platnick, N. I. & M. U. Shadab, 1981e. A revision of the spider genus Sergiolus (Araneae, Gnaphosidae). American Museum Novitates 2717: 1-41, PAGE 28. (full text available here:
Internet References
~ - Image from WA.
Works Cited
1.A Revision of the Spider Genus Sergiolus
Platnick, Norman I.; Shadab, Mohammad U. 1981. Am. Mus. Novit. 2717: 1-48.