The genus Xiphinema in South Africa. 3. Two new species of the X. hallei- group with additional information on X. vanderlinei Heyns, 1962 and X. dimorphicaudatum Heyns, 1966 (Nematoda: Dorylaimida). Phytophylactica, 8(3) 1976: 67-78. 73 [Zoological Record Volume 113]