110-million-years-old fossil suggests early parasitism in shrimps.

Direct evidence of paleo-parasitism in crustaceans is very scarce. Epicaridean isopods are obligatory parasites of crustaceans, including decapods such as crabs, shrimps, and lobsters. Their interaction with hosts is known from fossils as far back as the Jurassic through deformations of the branchial cuticle on the hosts. Their small size and low fossilization potential, outside of those larvae that have been found in amber, makes understanding the group's evolution challenging. Here, we report the oldest evidence of paleo-parasitism in marine shrimps and an imprint of a putative adult parasite that appears to be an epicaridean isopod. Our results suggest that the parasite-host interaction between epicaridean isopods and marine shrimps started at least 110 million years ago, and the Tethys Sea was a possible dispersal pathway for this lineage of parasites during the Jurassic and Cretaceous, as known for other marine organisms through most of the Mesozoic and Cenozoic. The oldest fossil records of bopyrid swellings associated with a large number of decapods from the Jurassic in Europe suggest that the Tethys region was a center of epicaridean distribution as a whole. Recent parasitic isopods found on dendrobranchiate shrimps are restricted to the Indo-Pacific and may represent a relict group of a lineage of parasites more widely distributed in the Mesozoic.

A new species of Pseudione Kossmann, 1881 (Crustacea, Isopoda, Bopyridae) parasitizing the squat lobster Munida microphthalma A. Milne-Edwards, 1880 in the Southwestern Atlantic.

A new species of Pseudione Kossmann, 1881, is described from 21 parasitized individuals of the squat lobster Munida microphthalma A. Milne-Edwards, 1880, collected in Brazilian waters of the southwestern Atlantic Ocean. The new species belongs to the Pseudione "crénéles" group sensu Bourdon (1976). The number of specimens obtained as well as the life history stage diversity of the type series, consisting of mature females, mature males, subadult males and cryptoniscus larvae, are unusually large for bopyrid isopod type series.

A new species of Aspidophryxus G.O. Sars, 1883 (Crustacea, Isopoda, Dajidae) from Caribbean mysid shrimp.

A new species of dajid isopod in the genus Aspidophryxus G.O. Sars, 1883 is described from three females and one male found infesting the lateral carapace of Heteromysis (Olivemysis) actiniae Clarke, 1955 (Mysidae: Heteromysinae) associated with the corkscrew anemone Bartholomea annulata (Lesuer, 1817) (Anthozoa: Aiptasiidae) from the British Virgin Islands. This is the first record of the genus from the western Atlantic; three other species are known from northern European waters, the central Atlantic and Japan, all on mysid hosts. The new species is the first dajid recorded from tropical Caribbean waters. A key to species in the genus and a list of all known hosts with parasite orientation are provided.