Caeciliusidae

Introduction

Caeciliusidae (formerly called Caeciliidae) contains about 600 described species in more than 35 genera.  The family is distributed worldwide with most diversity in Asia and Africa.  There are about 35 species of the family in North America.

Caeciliusids are small to medium-sized bark lice (~3 mm in length).  Body color is generally yellow.  Caeciliusids are leaf-inhabiting bark lice that live on conifers and broad-leaf trees.  Most are long-winged, but some of the few ground litter species have both long- and short-winged females. This is the largest family of leaf-inhabiting bark lice.

Characteristics

Synapomorphies

None.

General Characters

• Head:    
  
• Head is short.
• Antennae have 13 segments.
• Ocelli are grouped on a tubercle.
• Mandibles have an open appearance:
• usually elongate and hollowed out posteriorly
• to accommodate large, bulging galae (cheeks).
• Legs:
  
• Tarsi have 2 segments.
• Wings:  
• Forewing:
• Veins Rs and M are often fused for part of length.
• Areola postica is free.
• Branches of veins have a singe row of hairs.
• Margin has more than one row of hairs.
• Marginal hairs do not cross one another as in Pseudocaeciliidae.
• Vein CuP may be have hairs or not.
• Wing membrane is nearly always hairless.
• Hindwing margin has hairs all around except basal 2/3 of front margin.
• Abdomen:
  
• Abdomen has vesicles (inflatable sacs) that excrete a sticky substance, used to adhere insect to substrate.
• Male: 
  
• Hypandrium is simple.
• Phallosome is closed anteriorly with rugose sclerification on penial bulb.
• Female:  Gonapophyses are reduced:
• Dorsal valve is usually slender.
• Ventral valve is usually slender.
• External valve is reduced to small sclerotised area with 0,1, or 2 hairs.
• Eggs:
  
• Eggs are smooth, laid in groups, and covered with silken strands.

How to Know the Family

• Small to medium-sized bark lice (~3 mm in length).
• Characteristic yellow color.
• Head is short.
• Ocelli are grouped on a tubercle.
• Tarsi have 2 segments.
• Mandibles have an open appearance, usually elongate and hollowed out posteriorly to accommodate large, bulging galae (cheeks).
• Labial palps are often somewhat triangular & protruding.
• Abdomen has vesicles (inflatable sacs) that excrete a sticky substance used to adhere insect to substrate.

Discussion of Phylogenetic Relationships

Caeciliusidae is one of the best studied families within Psocomorpha, due primarily to morphological work by E. L. Mockford.  Recent studies, however, have revealed that Caeciliusidae is not monophyletic.  While molecular data strongly supported the monophyly of the infraorder Caeciliusetae, the Caeciliusidae taxa included in the analysis (10 species in 8 genera)  are scattered throughout the infraorder (18S nDNA; Johnson et al. 2004).  An analysis of 12S, 16S, COI mtDNA and 18s nDNA that included two Caeciliusidae genera also showed a paraphyletic relationship, with Valenzuela and Xanthocaecilius grouped with a species of Stenopsocidae (Johnson & Mockford 2003).  Morphological analysis of the Caeciliusidae also indicates paraphyly, with no synapomorphic characters supporting the family (Yoshizawa 2002).

Other Names for Caeciliusidae

• Caeciliidae

References

Johnson, K. P. & E. L. Mockford. 2003. Molecular Systematics of Psocomorpha (Psocoptera). Systematic Entomology 28: 409-40.

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.

Lienhard, C. and C. N Smithers. 2002. Psocoptera (Insecta) World Catalogue and Bibliography. Muséum d'Histoire Naturelle, Geneva, Switzerland.

Mockford, E. L. 1993. North American Psocoptera (Insecta). Gainesville, Florida: Sandhill Crane Press.

Mockford, E. L. 1999. A Classification of the Psocopteran Family Caeciliusidae (Caeciliidae Auct.). transaction fo the American Entomological Society 125: 325-417.

Smithers, C. N. 1996. Psocoptera. Pp. 1-80, 363-372 (Index) in Wells A. (ed.) Zoological Catalogue of Australia. Vol. 26. Psocoptera, Phthiraptera, Thysanoptera. Melbourne: CSIRO Publishing, Australia.

Yoshizawa, K. 2002. Phylogeny and higher classification of suborder Psocomorpha (Insecta: Psocodea:'Psocoptera'). Zoological Journal of the Linnean Society 136: 371-400.