broad-faced sac spider

not listed

NNR - Unranked

not listed

Broad-faced sac spider is a common, small, ground-dwelling spider. It occurs in the United States from Maine to North Carolina, west to North Dakota and Texas, and in southern Ontario and Quebec Canada. There are just a handful of records in the far south and in the west. The outlying records probably represent introductions into areas outside the species actual range. It is found in mixed deciduous and coniferous forests under loose bark, rolled up in leaves, in leaf litter, and under stones; on fences; and in human houses. It often enters houses in the fall.

Females are 5⁄16″ to ⅜″ (7.5 to 10 mm) in length and have a ⅜″ to ¾″ (10 to 20 mm) legspan. The front part of the body (cephalothorax) is rather high and is rounded when viewed from the front, egg-shaped when viewed from above. The upper part (carapace) is thick, hard, dark reddish-brown, and shiny. It is densely covered with tiny pits (punctures) and is hairless except in the front. A longitudinal depression in the middle (dorsal groove) is shallow but distinct. There are indistinct black lines radiating out from the dorsal groove, but these cannot be seen against the dark background in most photos. The underside of the cephalothorax is reddish.

There are eight eyes in two rows of four each. All of the eyes are about the same size. The front (anterior) row is slightly curved forward. The rear (posterior) row is curved rearward, and the eyes are equally spaced. The jaws (chelicerae) are dark brown, stout, bowed outward, and hairy. The forward-facing margin has three teeth, the rear-facing margin has two teeth.

The abdomen is egg-shaped, pale yellow to light gray, and covered with short, semi-erect hairs. The pale abdomen contrasts strongly with the dark cephalothorax. There is a darker gray longitudinal stripe on the front half in the middle (cardiac region), but the abdomen is otherwise unmarked. There is no cluster of long hairs at the end.

The legs are thin and moderately long. They have no spines. The first pair is thicker than the others and is as long as the fourth pair. The third pair is the shortest. The first pair is medium or dark reddish brown or brownish-red, darker toward the tip. The second pair is lighter in color, the third pair lighter still, and the fourth pair is the lightest.

Female Body Length: 5⁄16″ to ⅜″ (7.5 to 10 mm)

Male Body Length: 3⁄16″ to ¼″ (5 to 6 mm)

Legspan: ⅜″ to ¾″ (10 to 20 mm)

None

Mixed deciduous and coniferous forests, human houses.

Mid-June to early November

Adult females may overwinter, especially if they find refuge in a heated house.

Sources

7, 24, 29, 30, 82.

Platnick, Norman I.; Shadab, Mohammad Umar (1974). "A revision of the tranquillus and speciosus groups of the spider genus Trachelas (Araneae, Clubionidae) in North and Central America. American Museum novitates ; no. 2553". American Museum of Natural History.

Common

The genus Trachelas was originally included in the the subfamily Trachelinae of the family Clubionidae. When that family was split up Trachelas was placed in the family Corinninae. An analysis of wandering spiders that do not use webs (RTA Clade) published in 2001 suggested that the subfamily belonged in its own family, but no reclassification was made at that time. A later analysis published in 2014 showed that the subfamily was not closely related to the other members in the family, and the subfamily was finally raised to family level.

Found in Stewartville Minnesota, Olmsted County on August 14, 2023. Second one found in a week's time. This one we caught live and identified using the Seek application.

Trachelas tranquillus broad-faced sac spider

Trachelas tranquillus, broad-faced sac spider, on Solomon's seal leaf at hedgerow of Barnes Prairie, Racine Co., WI. Photo was taken on September 16, 2017.

Need help identify them

… images were captured on the baseboard of the bedroom. I don't know what kind it is. I am not telling the wife about that one!

If you can help identifying these spiders that would be very helpful.

Location: Stewartville, Minnesota

Found in Stewartville Minnesota, Olmsted County on August 14, 2023. Second one found in a week's time. This one we caught live and identified using the Seek application.

Location: Prior Lake, Scott County

… images were captured on the baseboard of the bedroom. I don't know what kind it is. I am not telling the wife about that one!

If you can help identifying these spiders that would be very helpful.

Location: Albany, NY

Location: Barnes Prairie, Racine Co., WI

Trachelas tranquillus, broad-faced sac spider, on Solomon's seal leaf at hedgerow of Barnes Prairie, Racine Co., WI. Photo was taken on September 16, 2017.