punctated ground crab spider

not listed

NNR - Unranked

not listed

Punctated ground crab spider is a small crab spider. It occurs in the northern United States and across southern Canada. It is uncommon in Minnesota. It is found from May through August on tree foliage forests and woodlands.

Adults are hard-bodied and bristly. The female is 3⁄16″ to ⅜″ (5.4 to 8.7 mm) in length and has a legspan of ½″ to 11⁄16″ (12 to 18 mm). The male is much smaller, ⅛″ to 3⁄16″ (3.5 to 5.0 mm) in length.

The plate (carapace) covering the front part of the body (cephalothorax) is moderately high, slightly longer than wide, and smoothly rounded on the sides when viewed from above. When viewed from the side it is slightly convex, highest near the front, and it drops down toward the back near the base of the third pair of legs. The sides of the carapace are dark brown. There is a broad pale stripe in the middle that narrows toward the rear, and there is a narrow pale line on each lateral margin. The area around the eyes is pale. The rear of the carapace is overhung by the abdomen.

There are eight eyes arranged in two curved rows of four. The front (anterior) row is curved forward and the rear (posterior) row is curved backward. The lateral eyes are larger than the median eyes and are on low raised projections (tubercles). The anterior median eyes (AME) are closer to the anterior lateral eyes (ALE) than to each other. The posterior median eyes (PME) are closer to each other than to the posterior lateral eyes (PLE). The median ocular area (MOA), the area defined by the middle four eyes is broader than long and slightly narrowed in front. The plate on the face above the mouth (clypeus) is armed with several long spines. The jaws (chelicerae) are small and have no teeth.

The abdomen is large, broadly oval, widest toward the rear, and flattened above. It is mostly brown with a broad, sharply irregular stripe in the middle. It is pale around the outside edges and there are also short black bands on the rear half.

The legs are stout and fairly long. The first and second pairs of legs are long, strong, spiny, and nearly equal in length. They are normally held out and forward, like a crab. This is the feature that gives the family Thomisidae its common name. The third and fourth pairs are shorter and nearly equal in length. On the first pair, the third segment (femur) is slender and about four times longer than wide, and the fifth segment (tibia) has 3 or 4 pairs of stiff hairs on the upper side. The last leg segment (tarsus) on each leg has two claws at the end but these are not visible without magnification. The tarsi on all legs do not have a brush of hairs (scopula) on the underside, and there is no tuft of hairs (claw tuft) at the end on any leg.

Female Body Length: 3⁄16″ to ⅜″ (5.4 to 8.7 mm)

Male Body Length: ⅛″ to 3⁄16″ (3.5 to 5.0 mm)

Legspan: ½″ to 11⁄16″ (12 to 18 mm)

Crab spiders do not make webs.

Forests and woodlands

May through August

When the legs are held out to the side the spider is able to walk forward, backward, or sideways (laterigrade).

The female does not build webs, snares, or retreats. To protect its egg sac it will fold over the edge of a leaf and secure it with silk.

Insects and other spiders

Sources

24, 29, 30, 82.

Uncommon in Minnesota

Location: Woodbury, MN