broad-faced sac spider

(Trachelas tranquillus)

Conservation Status
IUCN Red List

not listed

NatureServe

NNR - Unranked

Minnesota

not listed

 
broad-faced sac spider
Photo by Brian Montgomery
 
Description

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 516 to (7.5 to 10 mm) in length and have a 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.

 

Size

Female Body Length: 516 to (7.5 to 10 mm)

Male Body Length: 316 to ¼ (5 to 6 mm)

Legspan: to ¾ (10 to 20 mm)

 

Web

None

 

Similar Species

 
Habitat

Mixed deciduous and coniferous forests, human houses.

Biology

Season

Mid-June to early November

 

Behavior

 

 

Life Cycle

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

 

Food

 

Distribution

Distribution Map

 

Sources

7, 24, 29, 30, 82, 83.

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.

10/2/2024    
     

Occurrence

Common

Taxonomy

Class

Arachnida (arachnids)

Order

Araneae (spiders)

Suborder

Araneomorphae (typical spiders)

Infraorder

Entelegynae

Zoosection

RTA clade

Zoosubsection

Dionycha

Family

Trachelidae (broad-faced sac spiders)

Genus

Trachelas

   

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.

   

Subordinate Taxa

 

   

Synonyms

Clubiona tranquilla

Trachelas ruber

   

Common Names

broad-faced sac spider

bullheaded sac spider

large contrasting corinne spider

 

 

 

 

 

 

 

Glossary

Carapace

The hard, upper (dorsal), shell-like covering (exoskeleton) of the body or at least the thorax of many arthropods and of turtles and tortoises. On crustaceans, it covers the cephalothorax. On spiders, the top of the cephalothorax made from a series of fused sclerites.

 

Cephalothorax

The front part of the body of various arthropods, composed of the head region and the thoracic area fused together. Eyes, legs, and antennae are attached to this part.

 

Chelicerae

The pair of stout mouthparts, corresponding to jaws, in arachnids and other arthropods in the subphylum Chelicerata.

 

 

 

 

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Alfredo Colon

broad-faced sac spider  

broad-faced sac spider

Shirlie Sharpe

broad-faced sac spider
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.

Babette Kis

broad-faced sac spider

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.

Brian Montgomery

broad-faced sac spider  

broad-faced sac spider

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.

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Other Videos

Bashful Bullheaded Sac Spider
Bob TheSpiderHunter

About

Oct 29, 2017

This video is a teaching video on the Bullheaded Sac spider, Trachelas tranquillus, an easy-going ground hunter that I chose to highlight! Some fear this spider, but it is not in this species to be aggressive, but rather laid back. Join with me, listen to some relaxing music, less narration, but plenty of good teaching on this rather "bashful" spider and little know spider.

Trachelas Tranquillus Also Know as The Broad Faced Sac Spider Spotted in Bristol CT on 10/6/22
Kevin's BERGERON Bristol Connecticut storm chaser

About

Oct 5, 2022

 

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Visitor Sightings
 

Report a sighting of this arachnid.

 

This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Be sure to include a location.

Alfredo Colon
6/10/2024

Location: Albany, NY

broad-faced sac spider
Shirlie Sharpe
8/14/2023

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.

broad-faced sac spider
Brian Montgomery
9/28/2022

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.

broad-faced sac spider
Alfredo Colon
8/18/2022

Location: Albany, NY

broad-faced sac spider
Babette Kis
9/16/2017

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.

broad-faced sac spider
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Created: 10/12/2022

Last Updated:

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