Identification
Females
N. arabesca - Small and brightly colored and the pairs of slanting black commas down the dorsum are diagnostic. Body oval shaped.
N. crucifera (formerly hentzii) - Seems to be the one with the least well defined pattern.
N. domiciliorum - “bright white or yellow on the anterior dorsal” - “almost transverse bars on each side of the posterior”
also note Lynette's Forum
here
N. nautica - “Sides are black with lobed edge toward lighter dorsum”
N. oaxacensis - body elongate, large southwestern species, relatively unique pattern, but variable. May be confused with Aculepeira!
N. orizabensis - looks like a very dark N. oaxacensis or a very dark N. crucifera with bright yellow mottling.
N. pratensis - unique dorsal pattern, eastern wetlands
N. utahana - relatively small, “brown carapace, brown legs, dark brown triangular abdomen, darker on sides; dorsal folium sharply delimited by lighter line
Males
N. arabesca - Small and brightly colored. Northern variation: Tibia II curved with long macrosetae. Southern variation: tibia II nearly straight. The conspicuous presence of a large number of macrosetae on the ventral surface of tibia II is characteristic. Most can be ID'd by small size and dorsal marks.(Levi, pg. 474)
N. crucifera (formerly hentzii) - 4.5 to 15 mm, tibia II has two rows of clasping spines with run the entire length of the prolateral edge, a proximal bulge. (Levi, pg. 482)
N. domiciliorum - 8 to 9 mm, male may not be brightly colored, second tibia nearly straight and has three rows of clasping spines, and also has a proximal bulge. (Levi, pg. 477)
N. nautica - “Sides are black with lobed edge toward lighter dorsum” The male has a large median ventral macrosetae (one long hair growing off a bumb in the center of the tibia) that is diagnostic.
N. oaxacensis - body elongate, large southwestern species, relatively unique pattern, but variable. May be confused with Aculepeira!
N. orizabensis - looks like a very dark N. oaxacensis.
N. pratensis - unique dorsal pattern, eastern wetlands
N. utahana - Same shape and pattern of female, which should separate it from all other males in the genus, relatively small, “brown carapace, brown legs, dark brown triangular abdomen, darker on sides; dorsal folium sharply delimited by lighter line
Range
N. arabesca - Walckenaer, 1842 - AB, AL, AR, AZ, BC, CA, CO, CT, FL, GA, IA, ID, IL, IN, KS, LA, MA, MB, MD, ME, MI, MN, MO, MS, MT, NB, NC, ND, NH, NJ, NM, NS, NY, OH, OK, ON, OR, PA, PQ, RI, SC, SD, SK, TN, TX, UT, VA, VT, WA, WI, WV, WY
N. crucifera - Lucas, 1838 - AL, AR, AZ, CT, FL, GA, IA, IL, IN, KS, KY, LA, MA, MD, MI, MN, MO, MS, NC, NE, NJ, NM, NY, OH, OK, PA, SC, SD, TN, TX, VA, WI, WV
N. domiciliorum - Hentz, 1847 - AL, CT, FL, GA, IN, KY, LA, MA, MD, MS, NC, NJ, NY, OH, PA, RI, TN, TX, VA, WV
N. nautica - Cosmotropical
N. oaxacensis - Keyserling, 1864 - AZ, CA, IN, KS, NM, NV, RI, TX, UT, WA
N. orizabensis - Pickard-Cambridge - NM - Otero County (found in Mountain meadow)
N. pratensis - Hentz, 1847 - CT, FL, IL, KS, LA, MA, MI, MN, NC, ND, NY, ON, WI
N. utahana - Chamberlin, 1919 - CO, KS, LA, NM, OK, TX, UT
Remarks
Some species (usually collectively referred to as "barn spiders", i.e. Neoscona crucifera) are nearly impossible to distinguish from Araneus and can only be separated by examination of carapace to view the carapace groove (fovea). Neoscona have a longitudinal groove on the carapace (parallel with the long axis of the body), whereas Araneus have angular (transverse) grooves. However, an apparent problem is that in Araneus the groove may appear as little more than a dimple, making it tough to tell.
Neoscona
Araneus
Wasps like those in the subfamily Pimplinae can prey on spiders from this genus.