Two new Echinoderes species (Echinoderidae, Cyclorhagida, Kinorhyncha) from Nha Trang, Vietnam

No kinorhynchs have previously been reported at the species level from Vietnamese waters. Two new species in the Echinoderes coulli-group, Echinoderes regina sp. nov. and Echinoderes serratulus sp. nov., are described from Nha Trang, Vietnam, Southeast Asia. Echinoderes regina sp. nov. is characterized by the large trunk (451-503 μm), a middorsal spine on segment 4, sublateral spines on segments 6 and 7, lateroventral tubules on segment 5, sublateral tubules on segment 8, laterodorsal tubules on segment 10, large sieve plates on segment 9, a primary pectinate fringe with fringe tips wider middorsally to ventrolaterally and thinner ventromedially on segments 2-9, and lateral terminal spines (15-20% of trunk length). Echinoderes serratulus sp. nov. is characterized by a middorsal spine on segment 4, sublateral spines on segments 6 and 7, lateroventral tubules on segments 5 and 8, midlateral tubules on segment 9, laterodorsal tubules on segment 10, large sieve plates on segment 9, primary pectinate fringes with long fringe tips ventrally on segments 1-9, with the ventromedial tips obliquely orientated, pointing towards the midventral line on segments 2-5, and short, plump lateral terminal spines (12-15% of trunk length).