Aeshna sp.

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, Bulletin of the American Museum of Natural History 459 (1), pp. 1-184 : 1-184

Aeshna sp. immature

Figure 30 (lateral, dorsal, ventral)

Determining the correct placement and assessment of homology of the longitudinal trunks in the aeshnid adult required the scanning of an aquatic immature. The closed tracheal system of the naiad dragonfly is built around the rectal gills, and was first detailed by Scott (1905) and Tillyard (1917), whose terminology we adapt here.

The aeshnid naiad possesses four paired longitudinal trunks in the abdomen, one more than determined by Tillyard (1917). His Dorsal Trunk DT is our A n -DLT, and we adapt his Visceral Trunk VT as Visceral Longitudinal Trunk A n -VLT. However, Tillyard’s Ventral Trunk VNT is actually homologous to the Medial Longitudinal Trunk A n -MLT, as it follows the spiracles along the lateral body wall (see description for adult, below). The abdominal A n -VLT is depicted as shorter ventral branches (but not labeled) by Tillyard in his fig. 75 ( fig. 28 ). In figure 30 here it is barely visible in the ventral view but likely present as a longitudinal trunk. This specimen was collected early in the study and frozen to -20° C rather than -80° C, possibly causing smaller structures to be infilled with fluid, and the 30 µm scan resolution is not ideal for capturing smaller details such as these fine tracheae. Regardless, the presence of the branches leading to these more linear, ventrally located tracheae indicates that these are indeed A n -VLT.

Figures

FIGURE 28. Tillyard’s (1917) figure 75, showing three longitudinal trunks: dorsal trunk DT, visceral trunk VT, and ventral trunk VNT.

FIGURE 30. Aeshnid immature with longitudinal trunks labeled. Lateral (left), dorsal (middle), and ventral (right) views.