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Acesso aberto (Open Access)
Revisão taxonômica da família Ceramonematidae (Plectida, Nematoda).
(Universidade Federal do Pará, 2021-06-14) MACEDO, Rafaela Poliana dos Santos; VENEKEY, Virág; http://lattes.cnpq.br/1106411624280455; https://orcid.org/0000-0002-1061-2890
The family Ceramonematidae includes exclusively marine nematodes, found in coarse sands of shallow water and fine sediments such as silt and clay. Most works on Ceramonematidae are ecological and few are taxonomic. A significant number of species have sparse descriptions and simple sketch drawings (especially older works), which make it difficult to identify the group. This study aimed to taxonomically review the family Ceramonematidae, present its history and diagnosis, as well as its respective genera, in addition to providing updated taxonomic lists of the valid species of each genus. For the taxonomic review, the Handbook of Zoology was first used to obtain information about the history and diagnosis, in addition to obtaining a list of its valid genera. Then, the original descriptions of each species were consulted, available on the checklists on the Nemys website. Based on the taxonomic review carried out in the respective study, Ceramonematidae has 7 valid genera and one inquerenda genus, being thus classified in previous works; totals 65 valid species, 2 inquerenda species, 10 nomen nudum species and the subfamilies Ceramonematinae and Pselionematinae are currently not valid. In addition, in some cases, it was found that the drawings of the original descriptions are very simplified and without much richness of details, which makes it difficult to visualize the cuticle ornamentation and to compare some structures, as the characteristics of the cuticle are important for identification at the species level. In this taxonomic review, tables and comparative figures for the species within each genus were developed, as well as lists of synonyms, species inquerenda and nomen nudum. Additionally, species and genera diagnoses were provided, adaptations were made whenever necessary, such as descriptions of the amphidian shapes of some species. Based on the survey of morphological characters of Ceramonematidae, it was concluded that the main characteristics that should be observed for the identification of genera are: number of cuticle ringlets, type of head arrangement, head capsule dimensions and amphidia shape. As for the species, the number of cuticle rings and the arrangement of the bristles in the cephalic capsule proved to be relevant in their differentiation. In this sense, for future work, an update of the original drawings and descriptions would be of great importance, as well as the elaboration of a taxonomic key for Ceramonematidae.
Acesso aberto (Open Access)
Taxonomia de brachiopoda (Família Discinidae Gray, 1840) da Formação Manacapuru (Siluro-Devoniano), Bacia do Amazonas, sudoeste do Pará
(Universidade Federal do Pará, 2020-05-29) CORRÊA, Luiz Felipe Aquino; RAMOS, Maria Inês Feijó; http://lattes.cnpq.br/4546620118003936; 4546620118003936
Discinoids are inarticulate brachiopod exclusively marine with two organophosphate valves that arise during Ordovician and can be divided into four living genera. The remarkable marine transgressions at northwest Gondwana during Silurian-Devonian transition collaborated to make discinoids so abundant in South America during Devonian. Despite this big radiation during Devonian, rare records of this group are studied in Amazon and Parnaíba basins. In layers of Manacapuru Formation (Amazon Basin Siluro-Devonian), Ererê Formation (Amazon Basin Meso-Devonian) and Pimenteiras Formation (Parnaíba Basin Eifelian-Frasnian) there are occurrences with no taxonomic detailing. On the other hand, discinoids are easily found in Devonian deposits of Paraná Basin, especially in Ponta Grossa and São Domingos formations, as pointed by well advanced studies. This work aims the taxonomic study of brachiopods (Family Discinidae) of Manacapuru Formation, at the south border of the Amazon Basin, collected during “Paleontological Patrimony Rescue Program” of Belo Monte Hydroelectric Plant, at Vitória do Xingu city, Pará state. Four sampling points (C3P1, C9P1, C13P1 e C14P1) compose the stratigraphic profile of the study area, that consists, from bottom to top, of crystalline basement followed by a nearly 0.5 meters layer of massive fine grained sandstone, interlayered with clay lenses, but discinoids occur only in sandstone portions. Above that, a fine-grained sandstone layer display incipient lamination with disseminated discinoids. Finally, there is a nearly 2.1 meters layer of laminated siltstones where discinoids are concentrated at the bottom, associated with Rhynchonelliformeas; at the top of the layer, isolated lingulids occur. 272 brachiopods samples were analyzed: 205 Discinidae, 57 Rhynchonelliformea and 10 Lingulids. The focus of this research lies in Linguliformeas brachiopods that belongs to Family Discinidae. Taxonomic studies in 205 discinoids samples pointed to three species of Orbiculoidea d’Orbigny, 1847: O. baini Sharpe, 1856, (10 specimens), O. bodenbenderi Clarke, 1913 (5 specimens) and O. excentrica Lange, 1943 (34 specimens). In addition, O. sp. 1 (18 specimens) and O. sp. 2 (19 specimens) were preliminarily identified as Orbiculoidea, but the nomenclature was kept open; another 99 Orbiculoidea samples classification remained undefined due to poorly preserved samples. 20 specimens of Gigadiscina Mergl & Massa, 2005 also remained with open classification. Although some papers mention Orbiculoidea genera in Manacapuru Formation, this is the first record of O. baini, O. bodenbenderi, O. excentrica and Gigadiscina genera in this formation, as well as the first documented occurrences of these species and genera in North of Brazil. The discinoids association studied in this paper (Gigadiscina? sp., O. baini, O. bodenbenderi, O. excentrica, O. sp. 1 and O. sp. 2) is the oldest (Lochkovian) record in South America (e.g. Paraná Basin / Pragian-Givetian; Alto das Garças sub-Basin / Givetian; Parecis Basin / Pragian; Chacoparanense Basin / Pragian; Pre-Argentinian Range / Pragian) and this can be explained by two main reasons: Laurasia and Gondwana (the main continental blocks) were apparently close enough to allow the cosmopolite invertebrate larvae (e.g. Orbiculoidea) to cross the oceans more easily. So, Amazon Basin was closer to Laurasia during Eodevonian, what made easier for these organisms to firstly accommodate in this basin. The other reason is that the global eustatic sea level increased during Eodevonian, leading to the great marine transgressions that reached many portions of Gondwana, favoring the emergence of shallow seas at northwest Gondwana, which is a favorable environmental condition for inarticulate brachiopods colonization, represented by the discinoids in marine sediments of Manacapuru Formation described in this paper. Shallow marine coast environments are the main habitat of Orbiculoidea genera. This affirmation relies, in a certain proportion, in the current distribution of discinoids in less than 30 meters depths: 92,7% of Orbiculoidea fossil records are associated to shallow marine conditions. Therefore, the presence of O. baini, O. bodenbenderi, O. excentrica, and Gigadiscina? sp. in Manacapuru Formation layers suggest a shallow marine environment, in agreement with what is already proposed for the upper portion of this formation.