The family Phoxocephalopsidae (Crustacea: Amphipoda) from Brazilian coastal waters with description of four new species.

Phoxocephalopsids are fossorial amphipods endemic to the Southern Hemisphere and currently encompass five genera and 15 species, including the four new species herein described. Previous records of the family along the Brazilian coast are limited to Phoxocephalopsis zimmeri Schellenberg, 1931. Based on material from the Crustacean Collection of Museu Nacional/UFRJ four new species of Phoxocephalopsidae areherein described: Phoxocephalopsis ruffoi sp. nov. from Rio de Janeiro, São Paulo, Paraná and Rio Grande do Sul (23o-30oS); Puelche irenae sp. nov. from Espírito Santo and Rio de Janeiro (19o-23oS); Puelche longidactylus sp. nov. from Bahia, Espírito Santo and Rio de Janeiro (12o-23oS) and Puelche mourae sp. nov. found only at Rio de Janeiro. High diversity was recorded from the Campos Basin region, which extends from the north of Rio de Janeiro to south of Espírito Santo (21o-23oS), with the presence of all four phoxocephalid species. A key to Phoxocephalopsidae species from Brazil, including P. orensanzi Barnard and Clark, 1982 is provided.

A new Munidopsis species (Galatheoidea, Munidopsidae) from the Southwestern Atlantic.

Six Munidopsis species are recorded to the Southwestern Atlantic: M. barbarae; M. erinacea; M. nitida; M. sigsbei; M. riveroi and M. transtridens. Herein a new Munidopsis species from Southwestern Atlantic is described: Munidopsis trindadensis sp.nov., was sampled off Trindade Island (Espírito Santo, Brazil) at 360 m depth and differs from all six species previously recorded in this region by the telson with seven plates.

New findings of the family Pardaliscidae from the deep-sea southwestern Atlantic: the genus Caleidoscopsis Karaman, 1974.

Caleidoscopsis is a deep-sea pardaliscid genus known previously only from the SE Atlantic Ocean (Angola Basin), NE Pacific Ocean (Mexico, Cedros Trench) and Indian Ocean (Madagascar). This is the first record of Caleidoscopsis from off the Brazilian coast, SW Atlantic Ocean. Samples were collected with box core and/or van veen grabs between Espírito Santo, Campos and Santos Basin (19o-27o S), and around 417-1974 m depths. Two new species is herein described, Caleidoscopsis carlosi sp. nov., which differs from all Caleidoscopsis species by antenna 1 geniculate; maxilliped palp, article 4 shorter than 3; pereopods 5-7, propodus shorter than dactylus; and pereopod 7 with propodus 7x longer than wide; and Caleidoscopsis karamani sp. nov., which can be distinguished by rostrum more developed, reaching half-length of article 1 of peduncle of antenna 1; antenna 2, peduncle, article 5 longer than 3 and 4; pereopod 7, propodus 13x longer than wide, subequal to dactylus; urosomite 1 covering part of urosomite 2, with 1 long dorsal tooth; urosomite 2 with 1 very long and thin dorsal tooth almost reaching the end of urosomite 3. Further on, Caleidoscopsis carlosi sp. nov. turn out to be a very common and abundant species along the study area, being found in 126 samples with a total of 146 specimens examined, when comparing with C. karamani sp. nov. that was found in only 5 samples with one individual each. A table of comparison and an identification key of the currently six known species of the genus are provided. The present study is an effort in understanding and unrevealing the deep-sea macrofauna from the Brazilian margin bringing new data on the family Pardaliscidae found in the slope of the Campos, Santos and Espírito Santo Basins.

Taxonomic status of the amphi-Atlantic species Plesionika acanthonotus (Caridea: Pandalidae): a multi-locus and morphological approach.

Deep-sea shrimps of the species Plesionika acanthonotus (Smith, 1882) and P. holthuisi Crosnier Forest, 1968 are morphologically similar and exhibit overlapping amphi-Atlantic distributions. In the literature, through morphological studies, there are reports of doubts about the validity of P. holthuisi and some authors believe that the eastern and western Atlantic populations of P. acanthonothus could represent two distinct species. The objective of the present study was to use molecular data to elucidate the taxonomic status of the two populations of P. acanthonothus. DNA sequences of two mitochondrial genes (16S rDNA and Cytochrome Oxidase subunit I) and a nuclear gene (Histone 3) were obtained for both species and for both populations of P. acanthonotus. The sequences were also obtained from Genbank for comparison. The trees (separate and multi-locus/partitioned genes) were generated by Bayesian Inference analyzes, and genetic divergence (Kimura-2-parameters) was also calculated. All specimens that had their DNA sequenced were examined morphologically to confirm their identification; morphological variations were noted. The genetic data showed that Plesionika holthuisi is closely related to P. acanthonotus, but clearly separated, indicating that P. holthuisi is a valid species. In the multi-locus analysis, the P. acanthonothus specimens were divided into two clades, one with the eastern Atlantic specimens and another with the western Atlantic specimens. However, this genetic separation was considered to be a population structuring for three reasons: (1) the genetic divergences of the two mitochondrial genes between these two groups (eastern Atlantic X western Atlantic) were smaller than the interspecific divergence for Plesionika; (2) the P. acanthonothus sequences of the Histone 3 gene showed no genetic variation; (3) in the analyzed individuals, no valid morphological character was found to support this separation. Thus, the conclusion of this study is that P. holthuisi probably is a valid species and P. acanthonothus presents two populations with mitochondrial divergences that could be in the process of speciation, but which currently represent only one species.

Cheirimedon foscae sp. nov. (Amphipoda: Lysianassidae: Tryphosinae) from the deep sea Campos Basin, Southwestern Atlantic Ocean.

A new species of lysianassid amphipod belonging to the genus Cheirimedon was collected on the continental slope of the Campos Basin, the largest oil reserve in Brazilian waters. This is the first record of the genus Cheirimedon from the Atlantic Ocean, which was previously restricted to the Antarctic and Tasmanian sea. The new species is fully illustrated and compared with related species. Additionally, a world key to the Cheirimedon species is provided.