Bathypelagic Mysids from the Northeastern Pacific

Abstract

Deep-water samples off the Oregon coast yielded two new genera, four new species, and resulted in a further description of a previously described species of the Suborder Mysida. The following mysids are described: (1) The new genus Bacescomysis, which includes B. pacifica, new species, and five species of Hansenomysis: H. birsteini Băcescu, H. peruvianus Bacescu, H. tattersallae Băcescu, H. abyssalis Lagardère, and H. atlantica Lagardere. In this genus, closely related to Hansenomysis, the unjointed plate on the exopod of the uropod is the distinguishing feature. Bacescomysis pacifica is distinguished by its eyeplate, second thoracic endopod, second male pleopod, and telson. (2) The new species Boreomysis pearcyi is unique in its antennal scale, third thoracic endopod, telson, and body length. (3) Dactylerythrops latisquamosa, new species, is distinguished by its telson, eye, antennal scale, and endopod of first limb. (4) Paramblyops sp. is recognized as a new species by its rostrum and eyeplate, but is too damaged for a complete description. (5) The new genus Gibbamblyops resembles Dactylamblyops and Pseudamblyops, but is distinguished by the anterior margin of the carapace, eye, antennal peduncle, fourth male pleopod, and telson. These characters also define the uniqueness of its species, G. longisquamosa. (6) Thalassomysis tattersalli Nouvel, 1942, had been partially described from a single specimen. Four additional specimens of this species are recorded here. Slight differences are discussed, plus a complete description of the antennal peduncle and telson, which were lacking in the original description, are provided here. (7) Seven specimens of Holmesiella anomala Ortmann provided information on regional variation and allowed an opportunity for detailed drawings.