Abstract Evidence is provided to support the synonymy of two species of sand crabs (Anomura: Albuneidae). Zygopa lalanai Ortiz, 2015 is a synonym of Zygopa michaelis Holthuis, 1961 and Lepidopa boykoi Ortiz, Tello-Musi and Morales-Moreno, 2018 is a synonym of Lepidopa benedicti Schmitt, 1935. Each of the recently described species was based on a single specimen collected well within the range of their respective senior synonyms.

Abstract The porcellanid crab Polyonyx gibbesi Haig, 1956, an obligate symbiont of Chaetopterus cf. variopedatus (Renier, 1804) in the western Atlantic, is parasitized by a rare entoniscid isopod. Crabs from coastal North Carolina and Florida, U.S.A., were dissected and examined for this internal parasite in 1966 and 1967. Two of 83 crabs (2.4 %) and 3 of 100 (3.0 %) crabs from North Carolina and Florida, respectively, were parasitized. Only female parasites were found, including five immature and three mature specimens; one host was parasitized by three immature entonicisds simultaneously. One of the mature parasites was liberating epicaridium larvae and the others had developing eggs or larvae. Parasitized female crabs were all ovigerous; the parasites did not castrate the hosts. The parasite is identified as Entoniscus creplinii Giard and Bonnier, 1887, previously known only from Brazil, and the female is redescribed.

Abstract A putative new species of tantulocaridan is reported parasitizing a species of typhlotanaid (Tanaideacea) from the Gulf of Mexico at depths up to 2767 m. The tantulocaridan belongs to Microdajus Greve, 1965, species of which are all known from tanaid hosts in the superfamily Paratanoidea. Tantulocaridan samples included newly settled tantulus larvae, early stages of trunk development and developing males; parasites were found attached to anterior appendages (antennules and pereopods) or bodies of hosts. This material likely represents a new species but the condition and number of available specimens precludes a formal description. The putative new species is most similar to Microdajus aporosus Grygier and Sieg, 1988 and Microdajus tchesunovi Kolbasov and Savchenko, 2010 in having an endopodal seta on each of the sixth thoracopods (lacking in other species). Microdajus tchesunovi is the only described species of Microdajus with males bearing unsegmented sixth thoracopod protopods; this character is also found on the present specimens. Males of the newly reported tantulocaridan can be distinguished from those of M. tchesunovi based on protopod 1-5 morphology and setation of the pits on the cephalothorax (fewer setae in males of the western Atlantic specimens compared to M. tchesunovi). This is the first species of Microdajus reported from the western Atlantic and the first tantulocaridan known from the Gulf of Mexico or northwestern Atlantic.

Abstract The family Bopyridae Rafinesque, 1815 is comprised of parasitic isopods with a life cycle involving an intermediate host (copepod) and a definitive host (decapod crustacean). The genus Anuropodione Bourdon, 1967 occurs in all oceans and encompasses five species that are only known as parasites of squat lobsters belonging to the genus Munida Leach, 1820. Despite the broad distribution of the genus, no species has ever been recorded from the South Atlantic. A total of 416 specimens of Munida iris A. Milne-Edwards, 1880 were collected in Potiguar Basin around the isobaths of 400 m, including 24 individuals (5.77%) containing parasites within their branchial chambers. Male parasites showed considerable variability in the number of pleomeres, with many showing four pleomeres, a number previously unknown for males of any species in the genus. These specimens represent the first occurrence of the genus Anuropodione and the species A. carolinensisMarkham, 1974 from the South Atlantic (Brazilian waters).

Abstract In the present paper, a new species of Achaeus Leach, 1817, is described from Easter Island and dedicated to the memory of Michael Türkay. This record represents the first inachid spider crab and the sixth endemic brachyuran to be described from the island. It can be differentiated from congeners by its relatively short carapace, with the postorbital region not elongated, the arrangement and number of tubercles on the dorsal carapace surface, prominent hepatic lobe, presence of a large anterodistal lobe on the ocular peduncle, as well as structures of the third maxilliped and ambulatory legs.