Trachelas tranquillus is a common small spider (female length 6.8 to 10 mm, male length 5 to 6.1 mm) in the eastern United States. It has a reddish brown cephalothorax that is covered with tiny punctures above and below. The abdomen is pale white to yellow with a darker stripe extending half way down the midline of the top surface of the abdomen. The anteriormost (forward) two pairs of legs have a reddish brown color similar to that of the cephalothorax while the more posterior (rearward) legs are colored like the abdomen and less stout than the anterior legs. Trachelas tranquillus is found in leaf litter in the summer and fall, but often turns up indoors during these seasons as well. It does not build a web. It occurs from New England and adjacent Canada south to northern Alabama and Georgia and west to Minnesota and Kansas. Within this range, the slightly smaller but very similar T. similis can be distinguished under magnification by examining the spacing of the anterior eyes and the height of the clypeus; T. deceptus (formerly known as Meriola decepta) is much smaller and has the posterior row of eyes straight rather than recurved (a recurved row has the median eyes farther forward than the lateral eyes). Although the genus Trachelas was formerly placed in the subfamily Corinninae within the family Clubionidae, the Corinninae is now widely treated as a family, Corinnidae.
(Comstock and Gertsch 1948; Kaston 1978; Howell and Jenkins 2004; Ubick and Richman 2005)
- Platnick, N.I. and M.U. Shadab. 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.
- Comstock, J.H. (revised and edited by W.J. Gertsch). 1948. The Spider Book, Comstock Publishing Company, Ithaca, New York.
- Howell, W.M. and R.L. Jenkins. 2004. Spiders of the Eastern United States: a Photographic Guide. Pearson Education, Boston.
- Kaston, B.J. 1978. How to Know the Spiders, 3rd edition. Wm. C. Brown Company, Dubuque, Iowa.
- Ubick, D. and D.B. Richman. 2005. Corinnidae. Pp. 79-82 in D. Ubick, P. Paquin, P.E. Cushing, and V. Roth (eds.). Spiders of North America: an Identification Manual. American Arachnological Society.