Banca de DEFESA: LAYSE KRISTINE CORREA LOPES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : LAYSE KRISTINE CORREA LOPES
DATA : 19/02/2019
HORA: 09:00
LOCAL: Sala de videoconferência do Auditório Paulo Cavalcante - MPEG
TÍTULO:

Anatomical characterization and its systematic implications for Selaginella (Selaginellaceae)

PALAVRAS-CHAVES:

Articulation. Stem. Estele. Phytoliths. Licophytes. Microphyll. Taxonomy.

PÁGINAS: 87
GRANDE ÁREA: Ciências Biológicas
ÁREA: Botânica
RESUMO:

1. In chapter 1, the proposed theme is related to the recent circumscription of S. subg. Gymnogynum that presents weaknesses in the definition and description of the articulation and the vascular system caulinar. In view of the above, the objective of this work was to describe and review the structural diversity of the articulations and the vascular system caulinar, as well as to provide additional information to delimit the species of S. subg. Gymnogynum. The samples were from Brazilian herbariums, representing subgenus Gymnogynum, Exaltatae and Stachygynandrum, where they underwent the herborization reversal process and subsequent treatments were assigned to light microscopy. As a result, all species of Gymnogynum and S. exaltata are articulated. Only S. anaclasta (subg. Exaltatae) and S. coarctata (subg. Stachygynandrum) do not present articulations. The region of the articulation can be characterized and classified based on the occurrence of elevations or nodules (hyperplasia), the predominant presence of pectin in the cell wall and the formation of grooves that reach up to the cortical region (constrictions), which combine to form five articulation types. The types of vascular system found were: haplostele, actinostele, plectostele and actino-plectostele. In Gymnogynum, the occurrence of bistelic haplostele was observed, besides two variations of actinostele and plectostele. The analysis of the stem allowed the standardized and revised characterization for the Brazilian species of subg. Gymnogynum, with additional information for the subgenus Exaltatae and Stachygynandrum, expanding the detailed anatomical database that could contribute to a more accurate delimitation of the taxa and to later studies of evolutionary history. In chapter 2, the proposed theme is related to the structures present in Selaginella microphylls that receive different denominations among them ―idioblasts‖ and ―papilas‖, where these structures appear to be silica bodies. However, there are no studies attesting to the composition and confirming their nature. The objective of this work was to fill the gaps regarding the knowledge of siliceous bodies in the genus, based on a comparative analysis of microphylls, with a significant sampling of five subgenera of Selaginella, to investigate the presence and distribution of silica bodies, aiming to reinterpret this character. The samples were from Brazilian herbariums, with 56 species representing the subgenus Exaltatae, Gymnogynum, Rupestrae, Selaginella and Stachygynandrum, where they underwent conventional treatments and were destined to scanning electron microscopy. In the microphylls it was found that the structures are silica bodies. Four leaf distribution patterns were observed according to the regions of the microphyll (margin, intermediate region and vein): medial-marginal; laminar; marginal; medial-costal. From the research done on microphylls, the creation of distribution patterns and terminological revision, certain taxonomic implications can be extracted and the presence of silica bodies is a potential synapomorphy for Selaginella. However, there is a need to deepen studies of the evolution of this character, and the anatomical analysis for the correct diagnosis is indispensable.  

MEMBROS DA BANCA:
Presidente - 943.759.762-68 - ANA CARLA FEIO DOS SANTOS - MPEG
Externo à Instituição - FERNANDA ILKIU BORGES DE SOUZA - EMBRAPA
Interno - 048.467.306-89 - PEDRO LAGE VIANA - MPEG
Interno - 013.077.336-03 - THAÍS ELIAS ALMEIDA - UFOPA