Maria Inês Feijó Ramos

Taxonomy and ecology of the Family Cytheruridae (Ostracoda) in Recent sediments from the northern Rio de Janeiro coast, Brazil

A study of the family Cytheruridae in Recent sediments from the coast of northern Rio de Janeiro State revealed the presence of four new species: (Hemicytherura auriculata, Oculocytheropteron delicatum, Oculocytheropteron circumcostatum and Semicytherura caudata,) and four previously described species (Semicytherura rugosoreticulata Whatley, Chadwick, Coxill & Toy, 1988, Oculocytheropteron macropunctatum Whatley, Chadwick, Coxill & Toy, 1988, Oculocytheropteron reticulopunctatum Whatley, Chadwick, Coxill & Toy, 1988 and Paracytheridea bulbosa Purper & Ornellas, 1989). A further two species Cytheropteron sp. and Kangarina sp. are left in open nomenclature due to paucity of the material. The ecology and distribution of the fauna suggest that the presence of many of these species, which also occur in colder waters off the coast of Uruguay and Argentina, is probably due to the upwelling of the South Atlantic Central Water in this area.

On the Miocene Cyprideis species flock (Ostracoda; Crustacea) of Western Amazonia (Solimões Formation): Refining taxonomy on species level

The Miocene mega-wetland of western Amazonia holds a diverse, largely endemic ostracod fauna. Among them, especially the genus Cyprideis experienced a remarkable radiation. Micropalaeontologic investigations of a 400 m long sediment core (~62 km SW Benjamin Constant, Amazonia, Brazil) permitted a taxonomic revision of about two-thirds of hitherto described Cyprideis species. We evaluate the diagnostic value of shell characters and provide an extensive illustration of the intraspecific variability of species. Based on comparative morphology, the 20 recorded Cyprideis species are arranged in groups and subgroups. The “smooth” group comprises C. amazonica, C. kotzianae, C. kroemmelbeini, C. machadoi, C. multiradiata, C. olivencai, C. paralela and C. simplex; the “ornate” group C. curucae nom. nov., C. cyrtoma, C. aff. graciosa, C. inversa, C. ituiae n. sp., C. matorae n. sp., C. minipunctata, C. munoztorresi nom. nov., C. pebasae, C. reticulopunctata, C. schedogymnos and C. sulcosigmoidalis. Five species have been revalidated, two renamed, two synonymised and two are new descriptions. Along with 10 further formally established species, for which a review is pending, Cyprideis keeps at least 30 endemic species in that region during Miocene times. Up to 12 Cyprideis species have been found to occur sympatrically, representing >90 % of the entire ostracod fauna. Ostracod index species enable a biostratigraphic allocation of the well succession to the Cyprideis minipunctata to Cyprideis cyrtoma biozones, corresponding to a late Middle to early Late Miocene age (late Serravallian–early Tortonian).

The taxonomy and zoogeography of the family Trachyleberididae (Crustacea: Ostracoda) from the Equatorial Continental Shelf of Brazil

A study of the family Trachyleberididae Sylvester-Bradley from the Equatorial Continental Shelf of Brazil (almost 1400 km in length) revealed the presence of five new species, which are described herein. These are: Cletocythereis atlantica, Cativella paratranslucens, Cativella reticulocostata, Henryhowella tuberculoclaviforma and Australimoosella polypleuron. Two sub-species of the genus Costa, C. variabilicostata brasiliensis subsp. nov. and C. variabilicostata aff. recticostata Bold, are placed within the variabilicostata group. The genus Neocaudites is represented by two species, N. subimpressus Edwards and N. triplistriatus Edwards, originally described from the Upper Miocene and Pliocene of the Duplin Marl, North Carolina, USA. The genus Puriana is represented by P. convoluta Teeter and P. variabilis Chukewiski & Purper, described originally from Belize (British Honduras) and the Brazilian coast, respectively. The geographical distribution of the studied fauna, reveals the presence of two assemblages on the Equatorial Continental Shelf of Brazil, a Northwest and a Southwest assemblage, separated by the area of discharge of the Amazon and Pará rivers and each with its distinctive oceanographical and sedimentological characteristics.

A minute ostracod (Crustacea: Cytheromatidae) from the Miocene Solimões Formation (western Amazonia, Brazil): evidence for marine incursions?

A huge wetland (the ‘Pebas system’) covered western Amazonia during the Miocene, hosting a highly diverse and endemic aquatic fauna. One of the most contentious issues concerns the existence, potential pathways and effects of marine incursions on this ecosystem. Palaeontological evidences (body fossils) are rare. The finding of a new, presumably marine ostracod species (Pellucistoma curupira sp. nov.) in the upper middle Miocene Solimões Formation initiated a taxonomic, ecological and biogeographical review of the genus Pellucistoma. We demonstrate that this marine (sublittoral, euhaline), subtropical–tropical taxon is biogeographically confined to the Americas. The biogeographical distribution of Pellucistoma largely depends on geographical, thermal and osmotic barriers (e.g. land bridges, deep and/or cold waters, sea currents, salinity). We assume an Oligocene/early Miocene, Caribbean origin for Pellucistoma and outline the dispersal of hitherto known species up to the Holocene. Pellucistoma curupira sp. nov. is dwarfed in comparison to all other species of this genus and extremely thin-shelled. This is probably related to poorly oxygenated waters and, in particular, to strongly reduced salinity. The associated ostracod fauna (dominated by the eurypotent Cyprideis and a few, also stunted ostracods of possibly marine ancestry) supports this claim. Geochemical analyses (δ18O, δ13C) on co-occurring ostracod valves (Cyprideis spp.) yielded very light values, indicative of a freshwater setting. These observations point to a successful adaptation of P. curupira sp. nov. to freshwater conditions and therefore do not signify the presence of marine water. Pellucistoma curupira sp. nov. shows closest affinities to Caribbean species. We hypothesize that Pellucistoma reached northern South America (Llanos Basin) during marine incursions in the early Miocene. While larger animals of marine origin (e.g. fishes, dolphins, manatees) migrated actively into the Pebas wetland via fluvial connections, small biota (e.g. P. curupira sp. nov.) were phoretically freighted and developed freshwater tolerance over long timescales. http://zoobank.org/urn:lsid:zoobank.org:pub:886C6476-393D-4323-8C0E-06BB8BD02FD9

Definition of regional ostracod (Cytheridella) morphotypes by use of landmark-based morphometrics

Geometric morphometric analyses were performed on the Neotropical ostracod Cytheridella including recent populations from Florida, Yucatán, Colombia, and Brazil. Generalized least-squares Procrustes analyses were applied to left and right valves of adult females and males and to A-1 to A-3 juveniles. The analyses show that the prevailing shape variability is in the outline of the valves. Further characters defining the variability range are the anterior pore conuli 2 and 4 (LM 2, LM 4) and the connection point between transversal sulcus and the extension of the posterior lobe (LM 6). Relative Warps Analysis enabled delineation of the whole-shape disparity and revealed a geographical pattern in the morphological variability that is apparent in adults and juveniles. Females show greatest morphological disparity, whereas juveniles are more variable on the population scale. Differences in hard- and soft-part morphology identify the specimens from Yucatán as new a morphospecies. Different hydrological or hydrochemical conditions may have led to the evolution of the new species. Cytheridella has occurred in the Neotropics since the Oligocene with a similar distribution to that in the Recent. Avian dispersal may repeatedly reintroduce C. ilosvayi to Yucatánian populations possibly explaining the sympatric occurrence of 2 Cytheridella morphospecies. Our findings promote the benefit of investigating morphological variability quantitatively to detect regional morphotypes and ultimately to contribute to evaluations of biodiversity.

Taxonomy and bathymetric distribution of the outer neritic/upper bathyal ostracodes (Crustacea: Ostracoda) from the southernmost Brazilian continental margin

Sixty-five ostracode species belonging to 41 genera and 17 families were recorded in the outer shelf and upper slope off Rio Grande do Sul and Santa Catarina states, southernmost Brazil, between 100 and 586 m water depth interval. The ostracode occurrences are hypothesized to be influenced by both, the coastal waters and the Antarctic Intermediate Water (AAIW). The taxonomy of some species of Bradleya Hornibrook, 1952, Legitimocythere Coles & Whatley, 1989 and Henryhowella Puri, 1957 previously described in the same study area is revised. Bradleya gaucha sp. nov., Legitimocythere megapotamica sp. nov., Apatihowella acelos sp. nov., Apatihowella capitulum sp. nov., Apatihowella besnardi sp. nov., Apatihowella convexa sp. nov., and Aversovalva tomcronini sp. nov. are herein proposed. Trachyleberis aorata Bergue & Coimbra, 2008 is reassigned to the genus Legitimocythere and Bradleya pseudonormani Ramos et al., 2009 has its diagnosis emended. Bythocypris praerenis Brandão, 2008 is considered a junior synonym of Bythocypris kyamos Whatley et al., 1998a. Apatihowella Jellinek & Swanson, 2003 and Legitimocythere species have well-defined bathymetric distributions and are potential paleoceanographic markers for the Quaternary in the Southern Brazilian Margin.

Late Oligocene–Miocene non-lunulate sand dollars of South America: Revision of abertellid taxa and descriptions of two new families, two new genera, and a new species

Material for all seven South American species of late Oligocene and Miocene scutelliform, non-lunulate sand dollars (Echinoidea: Clypeasteroida) was examined, resulting in revision of several taxa, and description of a new family, Placatenellidae n. fam., to house Placatenella n. gen. and Camachoaster n. gen. Known only from the state of Pará, Brazil, and previously described as a member of Abertella Durham, 1953, A. complanata Brito, 1981 is redescribed on the basis of analysis of the holotype and subsequently described material from the same region. A. complanata is removed from synonymy with A. pirabensis (Marchesini Santos, 1958), and transferred as the type species of Placatenella n. gen. A new taxon, Camachoaster n. gen., is described to hold C. maquedensis n. sp. The Abertellidae Durham, 1955 is revised and the concept of the genus Abertella restricted to include only those forms with a posterior notch and all interambulacra discontinuous, including A. pirabensis, which is redescribed from the only known specimen, confirming that this species lacks any trace of an anal lunule but possesses features fully congruent with its placement in Abertella. Iheringiellidae n. fam. is established to house the common but taxonomically challenging taxon, Iheringiella Berg, 1898. New data on the occurrence and location of the types of Iheringiella are discussed, and comments on the status of Eoscutella mirandae Parma, 1985 provided. A tabular key to all seven South American non-lunulates is given, along with discussion of the relationship between the posterior notch and the anal lunule.

Figure 6. Camachoaster Maquedensis N In Late Oligocene - Miocene Non-Lunulate Sand Dollars Of South America: Revision Of Abertellid Taxa And Descriptions Of Two New Families, Two New Genera, And A New Species

FIGURE 6. Camachoaster maquedensis n. sp., photographs of the oral surfaces of paratypes. A: MACN-Pi 5859, prepared specimen with pencil marks indicating plate architecture. B: MACN-Pi 5860, partially prepared specimen with pencil marks indicating plate architecture, faint tuberculation, and main branches of food grooves. Scale bars 10 mm in length.