1 Natural History Museum of Denmark, Natural History Museum of Denmark, Faculty of Science, Københavns Universitet2 Chair of Ecology and Biogeography, Nicolaus Copernicus University, Lwowska 1, 87-100 Toruń, Poland. Electronic address: email@example.com Natural History Museum of Denmark, Natural History Museum of Denmark, Faculty of Science, Københavns Universitet
Larval morphology is documented using both light and scanning electron microscopy for all three instars of the muscid fly Atherigona orientalis (Schiner), which is a species of known sanitary and forensic importance found in tropical and subtropical areas of all biogeographic regions. The unpaired sclerite in a form of a spicule is reported herein in the second and the third instar larvae. Occurrence of this sclerite was hitherto unknown in the second instar larvae of Muscidae and was only known from the third instar of several species, however not in a form of a spicule. Our study is the first report of the occurrence of the "sensory organ X" in all three larval instars of a species representing the family Muscidae. The bubble membrane, previously known only from third instar cyclorrhaphan larvae, is reported herein for the first time in the second instar. Characters allowing for discrimination of A. orientalis larvae from other forensically important Muscidae are summarised.