Morphology and differential diagnostics of parasitic larvae of some Strongylidae (Nematoda) of horses.

The morphology of L4 of Cylicostephanus minutus, Cylicotetrapedon bidentatus, Petrovinema poculatum, Cylicocyclus radiatus, C. triramosus, Cylicodontophorus euproctus, C. mettami, C. mongolicus, Poteriostomum imparidentatum, Gyalocephalus capitatus and Craterostomum acuticaudatum is discussed. The species are named in accordance with the new system, which is outlined in the introduction. The criteria for the identification of larvae killed during their 4th skinning include distinctive marks occuring in the 4th and 5th stages: gut morphology, position of cervical papillae, excretory opening, morphology of the caudal part of the female. For L4, generic characteristics have not been distinguished (except Petrovinema spp.). Larvae of small Strongylinae species are similar to those of Cyathostominae.