A new species of bopyrid isopod parasitic on the deep-sea squat lobster Munida spinosa from the Southwest Atlantic Ocean

Abstract

The taxonomy of the genus Pseudione remains unresolved. At present, a heterogeneous assemblage of species, not congeneric with the type species of the genus Pseudione, is provisionally called ´Pseudione sensu lato´. A new bopyrid that belongs to this group of species is herein reported. This parasite (an ovigerous female and its male) was found inside the right branchial chamber of Munida spinosa Henderson, 1885, a squat lobster that distributes along the Argentine Continental slope from off Buenos Aires Province to Malvinas (Falkland) Islands and Burdwood Bank. This infested squat lobster was obtained with a bottom otter trawl in the Mar del Plata submarine canyon (38°01.49´S, 54°44.17´W) at 819 m depth during the ´Talud Continental I´ survey, carried out by the Argentine RV Puerto Deseado in 2012. This is the first time a bopyrid isopod infesting Munida spinosa has been reported. This parasite has crenulated coxal plates and thus, it seems to belong to the Pseudione ´crénelés´ group proposed by Bourdon. This group currently contains eight species, all of them infesting anomuran decapods (families Munididae and Munidopsidae). The new parasite herein reported can be separated from the other species of the ?crénelés? group by presenting the following combination of characters: (1) frontal lamina narrow and smooth, (2) both sides of the body convex, and (3) tergal projections I-IV with irregular margins (more evident on right side). Finally, the taxonomic status of the ´crénelés´ group is briefly discussed.