Calodium hepaticum (Bancroft, 1893) Moravec, 1982 (syn. Capillaria hepatica) is a cosmopolitan capillariid nematode, infecting mainly rodents and occasionally other mammals, including humans. Reports of C. hepaticum in canids are rare and the present one is, to the best of our knowledge, the first reported case in a red fox (Vulpes vulpes Linnaeus) in Italy. Scanning electron microscopy (SEM) examination of the eggs of C. hepaticum allowed a precise description of the egg morphology, which is one of the most relevant specific characteristics of capillariid nematodes. The egg shell showed a fibrous beam-like network which differs from that of the eggs of closely related trichinelloid species. This characteristic can be useful especially in case of spurious infection, when misdiagnosis among different trichinelloids species can occur.
The egg shell of Huffmanela huffmani Moravec, 1987 forms three main layers: an outer vitelline layer, a middle chitinous layer, and an inner lipid layer. The vitelline layer, forming the superficial projections of the egg shell, comprises two parts: an outer electron-dense, and an inner electron-lucid part. The chitinous layer is differentiated into three parts: an outer homogenous electron-dense part, a lamellated part, and an inner electron-dense net-like part. The lipid layer comprises an outer net-like electron-lucid part, and an inner homogenous electron-lucid part. The polar plugs are formed by electron-lucid material with fine electron-dense fibrils.