Thesis (PhD(Agric))--Stellenbosch University, 2001. / ENGLISH ABSTRACT: The genus Helicotylenchus Steiner of the family Holplolaimidae is reviewed. The different morphometric and morphological characters used in species description are discussed. Thirty-five species occurring in South Africa, French Guiana and the French Caribbean Islands are redescribed, based on type and other material. A new species, viz. H. marethae n.sp. is described from South Africa. Apart from line drawings SEM micrographs are included for most species. / AFRIKAANSE OPSOMMING: In hierdie monograaf van die genus Helicotylenchus van die familie Hoplolaimidae, word die verskillende morfologiese en morfometriese eienskappe gebruik in spesie beskrywings, bespreek. Vyf-en-dertig van die spesies wat in Suid- Afrika, Frans Guiana en die Franse Karibiese Eilande voorkom word op grond van tipe of ander materiaal herbeskryf. 'n Nuwe spesie H. marethae afkomstig vanaf Suid- Afrika word beskryf. Behalwe vir lyntekeninge word SEM mikrograwe van meeste van die spesies ook gegee.