Angiostoma margaretae n. sp (Nematoda: Angiostomatidae), a parasite of the milacid slug Milax gagates Draparnaud collected near Caledon, South Africa.

Angiostoma margaretae n. sp. (Angiostomatidae) is described from the oesophagus of the slug Milax gagates Draparnaud collected near Caledon in the Western Cape Province of South Africa. The new species closely resembles another parasite of a milacid slug, A. milacis Ivanova & Wilson, 2009, with a similar head, stoma and spicule shape, the presence of distally outstretched ovaries, coiled oviducts, the same number of caudal papillae and enlarged rectal glands. However, A. margaretae differs from the latter by having: a shorter, wider tail with a rounded vs pointed tip; the distal parts of both ovaries with a particular hook-like shape due to an expansion closely following the short initial zone; ovoviparous females; and a different arrangement of male papillae. A. margaretae is comparable with A. limacis Dujardin, 1845, A. asamati (Spiridonov, 1985), A. coloaense (Pham Van Luc, Spiridonov & Wilson, 2005) and A. stammeri (Mengert, 1953), which have a similar stoma shape and size, but can be readily differentiated by the presence of distally outstretched vs reflexed ovaries and the presence vs lack of enlarged rectal glands. The new species has a similar arrangement of the ovaries to A. kimmeriense Korol & Spiridonov, 1991 and A. zonitidis Ivanova & Wilson, 2009, but is clearly differentiated by the lack of an off-set lip region and presence of a large bowl-shaped vs tubular stoma and less numerous male caudal papillae (seven pairs vs nine in A. kimmeriense and 10 in A. zonitidis).