Theristus (Penzancia) anoxybioticus n. sp. (Nematoda: Xyalidae) from Sublittoral Methane Seepages in the Northern Kattegat, Denmark


  • Preben Jensen


The free-living marine nematode Theristus (Penzancia) anoxybioticus n. sp. is described from specimens collected in muddy sediment at 10-12 m water depth in the northern Kattegat, Denmark, where the benthic environment is influenced by methane seepages. Mean body length of the male is 1,121 [mu]m and of the female 1,159 [mu]m. Theristus (Penzancia) anoxybioticus n. sp. has one crown of 10 cephalic setae and a clavate tail tip without setae. The three caudal gland cells are prominent. The intestinal lumen is hexaradiate in cross section and the lining is devoid of microvilli. Reproductive adults have so far only been found in the uppermost centimeter of sediment, and their presence is restricted to April and May. Juveniles are found in deep anoxic sediment layers during other months of the year. Key words: Kattegat, marine nematode, intestine, methane, mud, nematode, new species, seepages, Theristus (Penzancia) anoxybioticus, ultrastructure.