ORDER PHASMATODEA Tracheal architecture of stick insects has most recently been investigated by Strauss (2021), with an emphasis on the prothorax and possible adaptations for sound reception. Here, three specimens were scanned: the basal Timema cf. californicum, the popular Australian stick insect Extatsoma tiaratum, and the Vietnamese stick insect Medauroidea extra- dentata. Although many basal taxa exhibit synapo- morphies found in sister taxa of a given monophyletic group, Timema exhibits numerous apomorphies and its tracheal system is quite distinct from Extatosoma and Medauroidea. Medauroidea appears to be more representative of the larger phas- mids, with good scan quality and characters that appear to be common to Extatosoma (which is more complex and somewhat harder to homolo- gize). Timema and Medauroidea are described here in detail; Extatosoma is covered here in a more basic fashion due to the substantial complexity in the abdomen. Future studies should focus on the unique morphology of the abdominal tracheae—resem- bling the jumble of dried, packaged ramen noo- dles—of Extatosoma and its possible functions.

Published as part of Herhold, Hollister W, Davis, Steven R, Degrey, Samuel P & Grimaldi, David A, 2023, COMPARATIVE ANATOMY OF THE INSECT TRACHEAL SYSTEM PART 1: INTRODUCTION, APTERYGOTES, PALEOPTERA, POLYNEOPTERA, pp. 1-184 in Bulletin of the American Museum of Natural History 459 (1) on pages 1-184, DOI: 10.5531/sd.sp.55, http://zenodo.org/record/7730159