MACNBR   00242
MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Evidence about the hybrid origin of Hypolepis ×paulistana Schwartsb. & J. Prado (Dennstaedtiaceae)
Autor/es:
AGUSTINA YAÑEZ; PEDRO BOND SCHWARTSBURD
Lugar:
Salvador Bahía
Reunión:
Congreso; XIV Congreso Internacional de Palinología; 2016
Resumen:
Hypolepis ×paulistana was recently described as a putative hybrid between H. stolonifera (var. stolonifera) and H. rugosula (subsp. pradoana). The taxon has intermediate morphology between the two parents, and is probably narrow endemic to the highlands of São Paulo, Brazil. The aim of this work was to analyze the spore morphology of H. ×paulistana and his parents in order to provide additional evidence of the hybrid origin. Spores were collected from the holotype (at RB) and from an isotype (at LP) of H. ×paulistana. The observations were made using light microscopy (LM) and scanning electron microscope (SEM). The spores are monolete and bilateral. In distal view, they are elliptic; the major equatorial diameter is 22?39 µm. In equatorial view, the proximal face is plane and the distal face varies between convex to sub-conical; the polar diameter is 20?31 µm. The lesurae is 25?27 µm, straight. The perispore is light brown at MO, equinate, with laterally fused spines,frequently forming sinuous crests and covered by thread connections between them. The exospore is yellowish to hyaline at MO and has verrucate ornamentation with spinules between verrucae. Additionally, mature spores are identified with various anomalies: collapsed spores, with concavities or plies in the wall and without protoplast; spores with anomalous lesurae or without it; spherical alete spores, of radial symmetry and 30?32 µm in diameter; diads of mature spores with irregular shapes and different sizes and amorphous small bodies ornamented by spines similar to those observed in the perispore. According to previous analyzes conducted in other species of ferns, the variability in the shape and size of the spores could be related to an abnormal division of spores stem cells and unequal distribution of chromosomes between daughter cells. Also, the collapse of some spores could be explained by protoplast loss. All these phenomena are associated with hybridization events. To conclude, the diversity of anomalies observed in Hypolepis ×paulistana and the similarities with previous studies in other taxa provide additional evidence about its hybrid origin.