Several new or little known Criconematina are reported from Fiji, New Guinea, Tonga and Western Samoa. Paratylenchus tui n.sp. from Vava'u, a northern island in the Tonga group, most resembles P. vandenbrandei De Grisse, 1962, in measurements and lateral field but the anterior portion of the head is modified into a prominent disc, offset by constriction, distinguishing P. tui n.sp. from this and other species. Gracilacus aonli (Misra & Edward, 1971) is redescribed from a Western Samoan population. A new genus, Syro, is described in the subfamily Criconematinae for four species (three of them new) indigenous to New Guinea and three known species from tropical Africa. The genus is based on criteria which have not formerly been much considered in the group or have been overlooked, namely: form of head, uneven arrangement of appendages around body, appendages (whatever their shape) produced by basic dichotomy at least posteriorly, and a short, triangular postvulval region of few annules bearing long dichotomous trailing appendages. The genus consists of: S. vexillatrix n.sp., S. chrisbarnardi (Heyns, 1970) n. comb., S. coronatus (Schuurmans, Stekhoven & Teunissen, 1938) n. comb., S. dracomontanus (Van den Berg, 1983) n. comb., S. hughdavidi n.sp., S. orphreyifer n.sp. and S. melanesicus (Andrássy, 1979) n. comb.; information additional to the original description is given on the last of these.