Silba israel is a member of the S. admiralis McAlpine group of species characterized
amongst Silba species by having pale tarsomeres and, in the male terminalia, by having
tall, narrow cerci and a slightly protruding surstylus bearing a number of large teeth.
The group includes S. admiralis from India, S. apodesma McAlpine, and S. namibia
MacGowan from southern Africa, and S. pappi Soós from Afghanistan. There are also
a large number of undescribed species from the Congo area in Central Africa. The main
distinguishing feature between species in this group is the shape and ornamentation of
the phallus. S. israel differs from these related species in that the phallus has two flattened,
ribbon-like, lateral processes.