Lepidodermella weissi, new species (Gastrotricha: Chaetonotida: Chaetonotidae) from northwestern Oregon, U.S.A.

Abstract. A new species of Lepidodermella (Gastrotricha: Chaetonotida: Chaetonotidae) is described from two streams in northwestern Oregon, U.S.A. This is the fourth species of freshwater gastrotrich reported from the Pacific Northwest region of the United States. The dearth of reports appears to be due more to a lack of study rather than a lack of gastrotrichs. Lepidodermella squamata is one of the species already reported from the Pacific Northwest, and occurs sympatrically with the new species described here. No other members of the genus have been reported from the Pacific Northwest. Three species of Lepidodermella have been reported previously from North America. The genus includes one marine species and 14 freshwater species. Lepidodermella weissi, new species, brings the number of freshwater species to 15 and can be distinguished from other freshwater members of the genus by the following characters: absence of parafurcal spines, absence of transverse anterior ventral plates, head width of less than 40 µm, head with five lobes, pharynx length 44 µm or less, adhesive tube length of 5 µm or more, more than 35 scales per middorsal column, presence of seven or fewer posterior midventral columns of scales, presence of a pair of posterior ventral plates, and the presence of several columns of spined scales between the ventral ciliary bands and the smooth scales of dorsum and sides.