Arthropod Systematics & Phylogeny 78(1): 133-170, doi: 10.26049/ASP78-1-2020-06
Comparative analysis of worker head anatomy of Formica and Brachyponera (Hymenoptera: Formicidae)
expand article infoAdrian Richter, Francisco Hita Garcia, Roberto Keller§, Johan Billen, Evan P. Economo|, Rolf Beutel
‡ Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan§ Researcher, Lisbon, Portugal| Okinawa Institute of Science and Technology, Kunigamigun, Okinawa, Japan¶ University of Jena, Jena, Germany
Open Access
An organism’s morphology plays a crucial role in its interactions with its environment. Therefore, comparative anatomical analysis is a critical basis to understanding the ecology, behavior, and evolution. While our knowledge of ant internal anatomy has considerably improved in recent years, it is still highly fragmentary, and many evolutionary questions remain unsolved. The current work is a contribution of a series of studies with the larger goal to increase our knowledge of ant head morphology and reconstruct the evolution of this tagma across the ant phylogeny. We investigated the head anatomy of “generalized” ant species from phylogenetically distant clades to establish a very solid basis for future works on the formicid head and its transformations. To achieve a multifaceted documentation, we used a broad array of techniques, including microphotography, scanning electron microscopy, μCT-scan based 3D-reconstructions, and histological sections. This enabled us to show many anatomical features in unprecedented clarity and detail. Our results outline considerable conservation of the main structural features across the ant tree of life, but they also reveal many details that could prove phylogenetically informative and/or functionally important. The cephalic digestive tract with its sclerotization, associated musculature, and glands is more diverse than previously reported. More work will be necessary to clarify the functional and systematic significance of the observed differences. The cephalic endoskeleton, especially the tentorium and torular apodeme, is identified as a second structural complex of high potential. This previously neglected character system is apparently functionally important and very likely phylogenetically informative. Our results improve the basis for reconstructing the groundplan of the formicid head and evolutionary transformations in the stem group and crown group. Future studies focusing on functional aspects and evolutionary changes of different elements of the head will help to create a complete picture of the evolution of this highly successful group of insects.
Ants, head, anatomy, skeletomusculatur system, 3D-reconstruction, μCT-scan, homology