The internal larval anatomy of two rodent bot fly species: Cuterebra fontinella (Diptera: Oestridae) and Cuterebra americana.

Species within the genus Cuterebra Clark, 1815 (Diptera: Oestridae: Cuterebrinae) are obligate parasites of rodents and other mammals during the larval stage, causing cutaneous myiasis. The internal larval anatomy of Cuterebra species remains unstudied, despite its potential utility for understanding their parasitic adaptations and for comparative studies with other Oestridae. The present study describes the internal larval anatomy of the species Cuterebra fontinella Clark, 1827 and Cuterebra americana (Fabricius, 1775), using micro-computed tomography-based virtual histological sections and 3-dimensional reconstructions. Both species show a broadly similar organization of the internal organs and tissues, with the digestive system being the main system within the hemocoel. The alimentary canal lacks gastric ceca and a crop; a condition shared with other Oestridae subfamilies, but which differs from the larvae of other Oestroidea families. The salivary glands are long and tubular, appearing morphologically distinct from those described in other Oestridae subfamilies thus far. The Malpighian tubules are uniformly thin and lack mineralized concretions, differing from the excretory organs of the oestrid species within the subfamily Oestrinae. The respiratory system shows little variation in relation to the basic tracheal scheme observed in the larvae of other cyclorrhaphous Diptera. Similarities and differences with the larvae of other Oestridae subfamilies and other Oestroidea families are discussed from a functional perspective, highlighting the value of nondestructive imaging techniques in comparative anatomical studies for contributing to a better understanding of the biology, evolution, and pathology of myiasis‑causing Diptera.