ORDER ORTHOPTERA Orthopteran anatomy (and some tracheae) has been diagrammed in classic works, but the first proper treatments of respiratory systems were by Vinal (1919: for Dissosteria carolina), Carpentier (1927: for Phasgonura viridissma), and Ander (1939: for Ensifera in general). Several tracheal terms were introduced using Orthoptera, particularly those involving auditory adaptations and saltatorial legs, and the work of these researchers (particularly Ander) was instrumental in mapping the tracheae here. More modern studies have focused on physiology, including ventilation in Schistocera gregaria in influential experimental works by Miller (1960a, 1960b, 1960c), active tracheal compression in Orthoptera observed via synchrotron imaging by Westneat et al. (2003), and the distribution of air spaces in Schistocera americana by Shaha et al. (2013). Four orthopteran specimens were scanned: Gryllus sp. (Gryllidae), Romalea microptera (Romaleidae), Tachycines asynamorous (Raphidophoridae), and a Meconema thalassinum (Tettigoniidae). Orthoptera tracheal morphology is best represented here in the scans of Gryllus and Meconema, and these are described here in detail. Notable features are described for the remaining specimens, but they are presented in a more basic manner due to the suboptimal quality of the scan of Tachycines and the substantial complexity of Romalea. The most comprehensive work to date on tracheal morphology of Orthoptera is by Ander (1939). His work formed the basis for many of the homology statements here, although we reinterpret some of his tracheae, in particular the supraventral (suv) in the prothorax and mesothorax. Ander indicates that the suv is absent in the metathorax in all Ensifera (his fig. 81). Interestingly, Ander cites Carpentier (1927) as the source for supraventral, where it does not go into the leg (Carpentier’s figure 3). However, Ander’s figure 83 details Gryllidae (fig. 81 is his overall view of Ensifera) and identifies three tracheae going into the proleg: pa, pp, and suv (supraventral), an apparent departure from Carpentier’s suv. Herein, T n -AL refers to Ander’s pa, T n -PL for pp, and T n -VL for pve. (Refer to table S 1 in the online supplement for all reassignments of labels and terms from previous studies.) Ander’s suv, more consistent than Carpentier’s, is likely T1-Cx (and even T1-PL in some taxa), designated here as such. Ander’s suf (suprafurcal), lvl (lateral lateroventral), and pf (postfurcal connective, apparently absent in Gryllus but present in other Ensifera) tracheae were not found to be homologous outside Orthoptera. His terminology is retained for descriptions of Orthoptera for convenience. The dorsum of the metathorax in both Gryllus (Gryllidae) and Meconema (Tettigoniidae) both possess T3-DB-Vi, paired air sacs reminiscent of a root vegetable, and ending blind (fig. 59, pl. 36). These tracheae are similar in morphology to those found in the ventral thorax of Dictyoptera for hearing, and their possible function as such should be investigated further.

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