I'm starting this to help us sort out the male orb-weavers. This is mainly for Araneus & Neoscona at this time.
FOUND BOTH IN WEST & EAST
Swollen Legs
Araneus diadematus - 8 mm, Tibia II strong with strong short spines
- No Dorsal Humps
Araneus diadematus
Araneus marmoreus - 6-8 mm, Tibia II swollen with many short stout macrosetae on the prolateral surface
- No Dorsal Humps
- males have black markings one edge of carapace, dorsal pattern very variable
- abdomen has dark posterior oblique marks
Araneus marmoreus
Araneus nordmanni - 8-10 mm, Tibia II swollen/bent with strong macrosetae
Araneus nordmanni
Araneus saevus - 12-14 mm, Tibia II swollen with macrosetae
Araneus saevus
Neoscona crucifera - 9-12 mm, Tibia II swollen prolatterally near base, with 2 uneven rows of short stout mactrosetae
- No Dorsal Humps
- mostly an eastern species, but found across the US in the south
- males have black bands on sides of carapace
Neoscona crucifera
No Swollen Legs
Araneus gemmoides - 5.5-8 mm, legs not modified
- only in the west are some specimens black
Araneus gemmoides
Araneus trifolium - 5-8 mm
- No Dorsal Humps
- abdomen usually white
Araneus trifolium
Eustala anastera - 4-6 mm, femur II with 3-5 ventral macrosetae
- No Dorsal Humps
- dorsal tubercle
- triangular abdomen
Eustala anastera
Neoscona arabesca - 4-9 mm, Tibia II usually curved in northern specimens
- The conspicuous presence of a large number of macrosetae on
ventral surface of tibia II is characteristic
- No Dorsal Humps
Neoscona arabesca
MAINLY WEST
Swollen Legs
Araneus andrewsi - 11 mm, Tibia II strong and bent with macrosetae
No Swollen Legs
Araneus gemma - 6-8.5 mm, legs not modified
Araneus gemma
Araneus illaudatus - 5-9 mm, legs not modified
- anterior median white line (most confused with male gemma)
Araneus illaudatus
Neoscona oaxacensis
Neoscona oaxacensis
Eriophora edax - 8-12 mm, legs not modified
- very southern species (TX, AZ, CA)
- light brown with white pigment and tiny black spots at base of setae
- carapace with deep longitudinal groove
- distinct posterior hump
MAINLY EAST
Swollen Legs
Araneus bicentenarius
Araneus bicentenarius
Araneus corticarius - 5 mm, Tibia II swollen
- heavy black border, & mid-line on carapace
- eastern US, but wider dist. in Canada, also in Alaska
Araneus corticarius
Araneus washingtoni - 5 mm, Tibia II swollen with strong setae
- limited to the northern tip of eastern US
Eriophora ravilla - 9-13 mm, Tibia II swollen at base, and basitarsus curved
- very southern species, Gulf coast
- legs banded
- capapace with deep longitudinal groove
Eriophora ravilla
No Swollen Legs
Araneus cavaticus - 10-19 mm, no modified legs
- can easily be recognized by their huge size and long legs
Araneus cavaticus
Araneus iviei - 7 mm (resembles male trifolium)
- black border on carapace
- eastern US, but wider dist. in Canada
Eustala emertoni - 4-5 mm, Femur II lacking macrosetae
- No Dorsal Humps
- No posterior tubercle
- triangular abdomen
Eustala cepina - 3-4 mm, Femur II lacking macrosetae, per Kevin Pfeiffer - no ventral macrosetae on femur I.
- No Dorsal Humps
- Posterior tubercle
- triangular abdomen
Eustala cepina
Neoscona domiciliorum - 8-9 mm, Tibia II nearly straight with 3 rows of clasping spines
- No Dorsal Humps
- May not be brightly colored like females
Resources
(1) The Diadematus Group of the Orb-Weaving Genus Araneus North of Mexico, Levi, 1971.
(2) The Orb Weaver Genus Neoscona in North America by Berman & Levi, 1971. -
PDF Here.
(3) The Insects and Arachnids of Canada Part 23, Dondale, Redner, Paquin & Levi, 2003.
(4) The Ravilla Group of the Orbweaver Genus Eriophora in North America by Levi, 1970.
PDF Here
