Abstract: | ![]() Six species of Colobomatus, five of which are new to science, were found in a survey of 26 species of sillaginid fishes in the Indo-west Pacific. Three of the species are closely related and occur in the head cavities of various species of their hosts. Colobomatus sillaginis West, 1983 is recorded in Sillaginodes punctata and 12 species of Sillago, from around the coast of Australia and in the Gulf of Thailand, representing many new host and locality records. Female C. asiaticus sp. nov. are described from southeast Asia and the Persian Gulf, in three species of Sillago. Female C. arabicus sp. nov. are described from two species of Sillago occurring only in the Persian Gulf. A second intrageneric grouping of three species of Colobomatus inhabits a different microhabitat: tubes of the lateral line scales. Each of these species infects several sillaginid fishes, and in contrast to members of the first species-group they are entirely allopatric with each other. In Australia, female C. fulloonae sp. nov. are described from three species of Sillago in northern waters, and female C. charleah sp. nov. are described from two species of Sillago and Sillaginodes punctata in southern waters. Female C. westi sp. nov. are described from three species of Sillago in the waters of eastern Asia (Japan, Korea and China). Only one male specimen of each of C. arabicus sp. nov., C. charleah sp. nov. and C. westi sp. nov. was found. |