A new kinorhynch genus from the Antarctic deep sea and a new species of Cephalorhyncha from Hawaii (Kinorhyncha: Cyclorhagida: Echinoderidae)

AbstractA new species of a new kinorhynch genus with affinities to the Echinoderidae and a new species of Cephalorhyncha are described. Polacanthoderes martinezi gen. et sp. nov. was collected during the German ANDEEP-1 cruise at 2290m depth north of the South Shetland Islands in the Southern Atlantic Ocean, approximately 170km north of the Antarctic Peninsula. Polacanthoderes is characterized by the presence of a first trunk segment consisting of a complete cuticular ring, and by each of the following ten segments consisting of one tergal and two sternal plates. Cuticular hairs and perforation sites are absent, but spines are present in middorsal, subdorsal, laterodorsal, midlateral, lateral accessory, lateroventral, ventrolateral and ventromedial series on segments 4–10. The ventral side of segment 1 has a very strong and conspicuous pectinate fringe, whereas fringes are indistinct or absent on posterior segment margins of the following segments. Due to segment 1 being composed of a closed ring and the following segments of a tergal and two sternal plates, as well as to the presence of aligned middorsal spines and lateral terminal spines but absence of a midterminal spine, Polacanthoderes is assigned to the family Echinoderidae.Cephalorhyncha liticola sp. nov. was collected in the intertidal zone of a high energy beach on the northeast coast of Oahu, Hawaii. The species is characterized by the sternal plate of segment 2 being incompletely separated anteriorly by a midventral fissure. Middorsal spines are present on segments 4–8, ventrolateral spines on segment 2, lateroventral spines on segments 5–9, lateral accessory spines on segment 8, and laterodorsal spines on segment 10. In addition, there are special sensory spots with conspicuous marginal cuticular hairs on segments 1–3, and very long pectinate fringes on the sternal plates of segments 3–10. The partly subdivided sternal plates on segment 2 show the species to belong to the echinoderid genus Cephalorhyncha