Under Construction


Emilie Bess and Kevin P. Johnson
Containing group: Troctomorpha


The family Pachytroctidae includes 10 genera and about 90 species distributed worldwide.  Four species in the genera Nanopsocus, Tapinella, and Pachytroctes are found in North America.


How to Know the Family

Discussion of Phylogenetic Relationships

Morphological study of the male genitalia of Troctomorpha supports monophyly of family Pachytroctidae based on the character of absence of the basal apodeme (Yoshizawa & Johnson 2006).  Molecular data from six species of Pachytroctidae divides the family into two groups, Pachytroctes + Peritroctes  and Tapinella + Nanopsocus, but the support for family monophlyly is ambiguous (18S nDNA; Johnson et al. 2004).  Further study will be necessary to resolve the relationships within the family.


Johnson, K. P., K. Yoshizawa, and V. S. Smith. 2004. Multiple origins of parasitism in lice. Proceedings of the Royal Society of London B 271:1771-1776.

Yoshizawa, K. and K.P. Johnson. 2006. Morphology of male genitalia in lice and their relatives and phylogentic implications. Systematic Entomology 31: 350-361.

About This Page

Emilie Bess
Illinois Natural History Survey, Champaign, Illinois, USA

Kevin P. Johnson
Illinois Natural History Survey, Champaign, Illinois, USA

Correspondence regarding this page should be directed to Emilie Bess at and Kevin P. Johnson at

All Rights Reserved.

Citing this page:

Bess, Emilie and Kevin P. Johnson. 2009. Pachytroctidae. Version 25 March 2009 (under construction). http://tolweb.org/Pachytroctidae/14456/2009.03.25 in The Tree of Life Web Project, http://tolweb.org/

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