Cyathostomum montgomeryi and its place in the Cyathostominae (Nematoda : Strongylidae)

Cyathostomum montgomeryi (Boulenger, 1920) K'ung, 1964, a common parasite o f zebras, has not been redescribed since its original description. It is st ill almost unknown outside of Africa. This species was placed in different tribes (Murshidiinea or Cyathostominea) by recent workers. As part of an in ternational effort to clarify the classification of the Cyathostominae of h orses, we studied 210 specimens from Burchell's zebra Equus burchelli antiq uorum Smith, 1841, from the Kruger National Park (Republic of South Africa) and Etosha National Park (Namibia) and made measurements of 15 males and 1 5 females. Specimens that we measured were larger than those described by B oulenger. Cyathostomum montgomeryi has 2 corona radiata or leaf crowns surr ounding the mouth. The internal leaf crown (ILC) is inserted near the middl e of the buccal capsule. The external leaf crown (ELC) has fewer elements t han the ILC. The bases of the ILC elements are inserted in a curved line on the wall of the buccal capsule, and those of the ELC elements are recessed from the tips of the elements of the ILC on which they rest. All of these characters are shared with the other species of the genus Cyathostomum. The extrachitinous supports are similar to those of Cyathostomum catinatum. Th e distal ends of the spicules are identical to others in the Cyathostominea but differ from those in the Murshidiinea. The bursa is typical for Cyatho stamum. Thus, we retain this species in the Cyathostominea.