Dasydemellidae

Introduction

Characteristics

Synapomorphies

• Head: Vertex has a pair of concave areas (shared with Amphipsocidae).
• Forewing: hairs have distinctive pattern (see below).
• Hindwing is hairless or has hairs along margin of cell R3 only.
• Female: the external valve of the gonapophyses is well developed.

General Characters

• Head:
• Antennae have 13 segments.
• Vertex has a pair of concave areas.
• Legs:
• Tarsi have 2 segments.
• Wings:
• Forewing:
• Hairs are present on veins on distal half of wing only.
• Hairs on wing veins are in 2 or more rows.
• Forewing has hairs on margin; they do on cross one another.
• Membrane is hairless or has very sparse hairs.
• Pterostigma is shallow.
• Areola postica is free from vein M.
• Hindwing:
• Hindwing is hairless or has hairs along margin of cell R3 only.
• Abdomen: Eversible vesicles (small inflatable sacs) present on underside of abdomen.
• Male: Genitalia are similar to other members of Caeciliusetae:
• Phallosome is closed, the tip has a rough texture.
• Hypandrium is simple, not ornamented, spine on free margin is relatively large.
• Female: 
  
• Subgenital plate lacks posterior lobe.
• Gonapophyses are somewhat reduced:
• Ventral valve is small.
• Dorsal valve is small.
• External valve is well developed.

How to Know the Family

• Large bark lice, 4-6 mm in length.
• Mandibles are large, insects look like their mouths are open.
• Abdomen has eversible vesicles (small inflatable sacs) on underside.
• Wings and body appear hairy.
• Forewing:
• Membrane is hairless or has very sparse hairs.
• Hairs on veins are in 2 or more rows.
• Hairs on margin do on cross one another.
• Pterostigma is shallow.
• Hindwing is hairless or has hairs along margin of cell R3 only.

Family Monophyly

Monophyly of family Dasydemellidae is supported by both morphological and molecular data. 

Two synapomorphic morphological characters unite the family: distinctive patterns of hairs on the hindwing and, in the female, the external valve of the gonapophyses is well developed (Yoshizawa 2002).  Molecular analysis including two species, Matsumuriella radiopicta and Ptenopsila sp., provides support for the monophyly of family Dasydemellidae (18S nuclear DNA; Johnson et al. 2004).

Discussion of Phylogenetic Relationships

Due to strong morphological similarity between the families Dasydemellidae and Amphipsocidae, there is disagreement as to whether Dasydemellidae should retain status as a family (Mockford 1993) or be included in family Amphipsocidae s.l. (Yoshizawa 2002). Molecular data suggest a sister relationship between Dasydemellidae and Stenopsocidae, and place Dasydemellidae , Stenopsocidae as sister to Amphipsocidae (Johnson et al. 2004).

References

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.

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

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