"A. silesiacus" was found in the cloaca of the European robin ("Erithacus rubecula"), the thrush nightingale ("Luscinia luscinia") and the common nightingale ("Luscinia megarhynchos") in Wroclaw, Poland, and of the European robin in Alsóperepuszta, Hungary. Described in 1980, it is the most recently classified species of the "Apororhynchus". "A. silesiacus" is named after Silesia, a region in Poland where the parasite was found. Specimens were between 3.21 and 3.51 mm in total length, with a maximum width of 0.80 to 1.05 mm at middle and the eggs were around 0.07 mm long and 0.035 mm wide. It has a proboscis wider than the anterior part of the trunk, with about 40 spiral rows of hooks, each row bearing 14 to 16 hooks. There are 28 to 31 giant nuclei in the body wall and 9 to 12 in the lemnisci. The testes are almost parallel. The parasite has been found infesting juvenile European robins indicating that the infestation occurred in the nesting area. "Apororhynchus" species exclusively parasitize avian hosts of different orders including owls, waders, and passerines. The parasite attaches to the cloaca and in some cases the intestinal wall using a hook-covered proboscis. Infestation can cause enteritis and anemia in Hawaiian honeycreepers.