Hystrignathus ferox n.sp. and Xyo xiphacanthus n.sp. (Oxyurida: Hystrignathidae) with additional data on Carlosia tijucana Travassos & Kloss, 1957

Summary Two new species of hystrignathid nematode are described from passalid beetles in Trinidad, West Indies. Hystrignathus ferox n.sp., from the mid-gut caeca of Verres furcilabris (Esch.) is easily differentiated from H. rugosus Travassos & Kloss, 1958 and H. rescens Travassos & Kloss, 1958 on the character of the lateral alae. In H. rugosus the alae extend to the anus and in H. rescens to the vulva whereas in H. ferox n.sp. the alae are much shorter and terminate about two body-widths anterior to the vulva. Xyo xiphacanthus n.sp., from the mid-gut caeca of Veturius transversus var. trituberculatus (Esch.), is characterized by the cervical spines extending about an oesophagus length posterior to the basal bulb. No other nominal species of Xyo has the spines extending so far posteriorly. X. histrix Cobb, 1898 and X. histrix sensu Christie, 1934 are regarded as species inquirendae. Carlosia tijucana Travassos & Kloss, 1957 is illustrated and additional data provided. ac]19810415