3 species in the US/Canada.
Zygiella webs usually have the viscid spiral threads missing from a definite sector between two radii in the upper part of the web, and in this open area a strong signal line extends from the hub to the spider's retreat. (1)
Z. atrica - a European species introduced apparently on the northern ocean coasts and around Lake Erie. Levi gives: In America from Nova Scotia to Long Island; Port Credit, Ontario and British Columbia coast & northern WA coast.
Z. nearctica – along the extreme northern pacific coast, across Canada (into Alaska), the northern states, south in the western states and in the Appalachians.
x-notata – introduced in America, down the atlantic coast from Maine to Virginia. The pacific coast from southern BC to southern Cal.
According to Kaston, the orb webs constructed by members of this genus usually have the spiral threads missing from a sector between two radii in the upper part of the web. In this open area, a strong signal line extends from the hub to the spider's retreat.(1)
For the northwest: "Which species can't be told from color alone. Z. x-notata and Z. atrica occur in urbanized habitats, the former on buildings and the latter on trees. Z. dispar is found in natural forest."
…Rod Crawford, 15 June, 2008
A few of the ones we've placed in Zygiella strongly resemble Nerine digna. However, It's a male Zygiella that resembles a female Neriene. See Zygiella then Neriene: