Evolution of attachment structures in the highly diverse Acercaria (Hexapoda)

Area of Science:

• Insect morphology and evolution
• Comparative anatomy of arthropods
• Phylogenetic analysis of insects

Background:

• Insects exhibit diverse leg adhesive devices crucial for locomotion and habitat.
• Previous classifications of Acercaria and their relationships remain debated.
• Understanding adhesive structures provides insights into insect diversification.

Purpose of the Study:

• To describe and illustrate adhesive devices across major Acercaria subgroups.
• To reconstruct the evolutionary history of leg attachment structures using cladistic analysis.
• To test current hypotheses on insect phylogeny, particularly the placement of Zoraptera.

Main Methods:

• Morphological characterization of leg adhesive structures in Acercaria.
• Cladistic analysis incorporating 118 morphological characters (19 distal leg, 99 body parts).
• Phylogenetic reconstruction to infer evolutionary relationships.

Main Results:

• Confirms monophyly of Acercaria, Psocodea, Phthiraptera, and Hemiptera.
• Zoraptera are not closely related to Acercaria.
• Supports monophyly of Auchenorrhyncha and Condylognatha (Thysanoptera + Hemiptera).
• Hairy adhesive devices are restricted to Heteroptera (Cimicomorpha).
• Arolium is ancestral but lost in some groups; pretarsal pulvilli evolved independently.
• Phthiraptera evolved specialized tarsal devices, lacking pretarsal ones.

Conclusions:

• Leg adhesive structures provide valuable phylogenetic information for insects.
• The evolution of adhesive devices is linked to the diversification of insect groups like Hemiptera.
• Cladistic analysis supports current hypotheses on major insect group monophyly and relationships.