First Quaternary Brazilian cave pollen record: morphological descriptions, taxonomic and ecological data

Abstract

This paper presents descriptions, and taxonomic and ecological data by the angiosperm pollen grains recovered from Quaternary sediments of the Gruta do Urso Cave, Tocantins State, Northern Brazil. Among recovered assemblage, 44 types of angiosperm pollen were identified. Most of the pollen types described here are related to the modern aboreal-shrub and herbaceous-subshrub taxa currently present in the plant communities of the Cerrado biome: (i) forest formations (Annonaceae, Aspidosperma, Ilex, Celtis, Trema, Tournefortia, Protium, Combretaceae-Melastomataceae type, Croton-type, Moraceae-Urticaceae type, cf. Bauhinia brevipes, Cassia, Pithecellobium, Peixotoa, and Cedrela); (ii) savannah formations (Anacardium, Astronium, Asteraceae Tribu Eupatorieae, Caryocar, Cyperaceae, Eriotheca-type, Ludwigia, Pseudobombax spp., Ouratea, Qualea, and Utricularia), and (iii) grasslands (Poaceae). Regarding the diversity of pollen types registered, the most representative botanical families were: Fabaceae (8), Malvaceae (4), Euphorbiaceae (3), Anacardiaceae (3), Apocynaceae (2), Cannabaceae (2), Sapindaceae (2) and Poaceae (2), which also occur in the Cerrado-Caatinga transition. Pollen data show paleovegetation during the Last Glacial Maximum and Holocene times out of the cave, and provides a reliable source for paleoecological, paleoenvironmental and paleoclimatic investigations. Keywords: palynology, Quaternary, paleovegetation, Brazilian savannah. Este artigo apresenta as descricoes morfologicas, dados taxonomicos e ecologicos de graos de polen de angiospermas recuperados de sedimentos quaternarios da Gruta do Urso, Estado do Tocantins, Norte do Brasil. Foram registrados 44 tipos polinicos que se relacionam com os taxons arbustivo-arboreos e arbustivo-herbaceos ocorrentes atualmente nas comunidades vegetacionais do bioma Cerrado: (i) formacoes florestais (Annonaceae, Aspidosperma, Ilex, Celtis, Trema, Tournefortia, Protium, Tipo Combretaceae-Melastomataceae, Tipo Croton, Tipo Moraceae-Urticaceae, cf. Bauhinia brevipes, Cassia, Pithecellobium, Peixotoa e Cedrela); (ii) cerrado sensu stricto (Anacardium, Astronium, Asteraceae Tribo Eupatorieae, Caryocar, Cyperaceae, Tipo Eriotheca, Ludwigia, Pseudobombax spp., Ouratea, Qualea e Utricularia) e (iii) gramineas (Poaceae). Quanto a diversidade polinica, as familias botânicas mais representativas foram: Fabaceae (8), Malvaceae (4), Euphorbiaceae (3), Anacardiaceae (3), Apocynaceae (2), Cannabaceae (2), Sapindaceae (2) e Poaceae (2), que tambem ocorrem na transicao dos biomas Cerrado-Caatinga. Os dados polinicos refletem a paleovegetacao do entorno da caverna durante o Ultimo Maximo Glacial e Holoceno, e constituem uma fonte confiavel para as investigacoes paleoecologicas, paleoambientais e paleoclimaticas. Palavras-chave: palinologia, Quaternario, paleovegetacao, Cerrado.