FUNCTIONAL-MORPHOLOGY AND ANATOMY OF THE POLYPNEUSTIC LOBES OF THE LAST LARVAL INSTAR OF TSETSE-FLIES, GLOSSINA SPP, (DIPTERA, GLOSSINIDAE)

This study examines the external and internal anatomy of the polypneus tic (respiratory) lobes in 8 species of tsetse larvae (Diptera: Glossi nidae). In the more primitive fusca group, the respiratory lobes are e ither ring-like (Glossina longipennis) or partially divided into 2 lob es (G. brevipalpis). Two distinctly separated lobes are present in the palpalis group (G. palpalis, G. tachinoides, G. fuscipes) and in the morsitans group (G. morsitans, G. pallidipes, G. austeni). Air enters the polypneustic lobes through narrow slits (stigmata) on the tips of numerous small spiracular papillae that are arranged in rows on both t he outer and inner surfaces of the polypneustic lobes. The openings on the spiracular papillae connect to an air tube that is sculptured wit h septa and pegs. The air tubes connect to an outer air chamber that i s likewise replete with a network of pegged septa. The outer air chamb er is connected to a fell chamber containing a dense network of filame ntous septa (spicules) that appear to function as an air filter. The f elt chamber opens into a large, sculptured inner air chamber that conn ects directly to the regular tracheal trunk. The polypneustic lobes ar e unusually hard and brittle due to strong sclerotization of the cutic le and are permeated with numerous cuticular pores. There is no eviden ce that trichomes or other structures present on the respiratory lobes are innervated. Copyright (C) 1996 Published by Elsevier Science Ltd.