lined orbweaver

not listed

NNR - Unranked

not listed

There are 186 species of spiders in the genus Mangora, all in the Western Hemisphere. Only seven occur in North America north of Mexico. In the United States, only four occur north of Florida. Of these, lined orbweaver (Mangora gibberosa) is the most common.

Lined orbweaver is a small, well known, typical orbweaver. It occurs in the United States from Maine to Minnesota south to Florida and Texas, and in southern Quebec and Ontario Canada. It is found in grassy areas, including fields, woodland edges, and roadsides.

The female is ⅛″ to 3⁄16″ (3.4 to 4.8 mm) in length with a 3⁄16″ to ⅜″ (5 to 10 mm) legspan. The male is a little smaller, ⅛″ (2.6 to 3.2 mm) long.

The front part of the body (cephalothorax) and the legs are grayish-green, brownish-yellow, or yellow. The cephalothorax is much smaller than the abdomen, more or less rounded at the rear when viewed from above, and moderately convex when viewed from the side. There are no horny outgrowths. There is a deep longitudinal furrow in the middle. A narrow black stripe extends from just behind the eyes into the furrow. The cephalothorax appears swollen on each side of the furrow. This feature is thought to be the source of the species epithet gibberosa, which means “extremely hump-backed” in Latin.

There are eight eyes arranged in two parallel rows of four eyes each. The rear row is curved forward, the front row is straight or slightly curved backward. All of the eyes are small, but the median eyes are larger than the lateral eyes, and the posterior median eyes (PME) are larger than the anterior median eyes (AME). On each side the lateral eyes are widely separated from the middle (median) eyes and are almost touching each other. The median ocular area (MOA), the area defined by the middle four eyes, is longer than wide and narrower in front than behind.

The abdomen is large and rounded. The front of the abdomen extends forward in a round point over the cephalothorax. There are no low rounded humps (tubercles) in the shoulder (humeral) area. The upper surface is white with yellow or grayish-green leaf-like markings (folium) and black lines and spots. It is sometimes also mottled with a network of brown or reddish-brown lines. There are three elongated spots on the front quarter of the abdomen, a black longitudinal line in the middle of the second quarter, and two longitudinal rows of spots on the rear half that often merge into solid lines. There are also three black oblique lines on each side of the abdomen. The underside is mostly brown with white spots and lines.

The legs are armed with long black spine-like hairs. The third segment (femur) of the first three pairs of legs is the same color as the cephalothorax. The remaining segments of all legs are mostly pale with dark areas at the end of each segment. There is a row of spines on the underside of the femur of the second two pairs of legs but not on the first two pairs. On the female there is a thin black line on the underside of the femur of the first and second pairs of legs. On the fifth segment (tibia) of the third pair of legs there are two oblique rows of 5 or 6 long slender hairs on the underside near the base. This feature distinguishes the genus Mangora from all other orbweavers.

Female Body Length: ⅛″ to 3⁄16″ (3.4 to 4.8 mm)

Male Body Length: ⅛″ (2.6 to 3.2 mm)

Legspan: 3⁄16″ to ⅜″ (5 to 10 mm)

A tightly woven hunting web is constructed in grass or on a low bush. It is called an “orb”, which gives this family of spiders its common name. The orb may be horizontal or slightly inclined. It is 6″ to 12″ (15 to 30 cm) in diameter, very large for such a small spider. It has 50 to 60 radii and numerous, usually closely spaced, sticky (viscid) spirals. There is sometimes a circular, bullseye-like decoration (stabilimentum) in the center made of numerous overlapping strands of silk.

Tuftlegged orbweaver (Mangora placida) abdomen has a single black stripe in the middle. The dark line on the carapace extends from behind the eyes to the base. There is no black line on the underside of the femur of the first and second pairs of legs. The web does not have a bullseye-like decoration in the center.

Fields, woodland edges, and roadsides

The female creates a cocoon for her eggs in a small leaf folded and reinforced by strands of silk. The eggs hatch in the fall. The spiderlings overwinter in the cocoon.

Sources

24, 29, 30, 82.

Very common

Location: Woodbury, MN

Location: Woodbury, MN