Comparison of pollen characters in Lysiostyles Benth. and allied genera (tribe Maripeae – Convolvulaceae)

Abstract

Pollen morphology and ultrastructure was studied for the monotypic genus Lysiostyles (Convolvulaceae, tribe Maripeae) distributed in Guyana, Suriname and Venezuela. Lysiostyles scandens is a liana with alternate leaves, thyrsiform inflorescence, white corolla with acuminate lobes, five epipetalous stamens, anthers with elongated connectives and a superior ovary with two carpels. The styles are glabrous, branched and divided at the base with cylindrical stigma and lignified and indehiscent fruits. Pollen was collected from specimens in the herbaria RB, L, and U. For observation under light microscopy (LM) and scanning electron microscopy (SEM), pollen grains were prepared using acetolysis. Non-acetolysed pollen grains were prepared for observation by transmission electron microscopy (TEM). Pollen is small to medium sized, isopolar, mostly subprolate, and subcircular amb, tricolpate and tectate with a wavy relief and microechinate tectum. The sexine is thicker than the nexine. The pollen features observed in Lysiostyles are important for the characterisation of the genus, as well as for understanding relationships within the tribe Maripeae (Dicranostyles and Maripa), and support patterns suggested by phylogenetic studies.

Keywords:

• aperture
• lianas
• microechini
• perforate
• tricolpate

Acknowledgements

The first author thanks CAPES for the PhD scholarship (88882.447848/2019-01). Thanks also to the curators of the RB, L, and U herbaria for permission to collect the botanical material. The authors wish to thank FIOCRUZ for allowing the performance of analyses under SEM and TEM and CNPq for a scientific research grant to FARS. This study was financed in part by the Coordination for the Improvement of Higher Education Personnel – Brazil (CAPES) – Financing code 001 and is part of the first author’s doctoral research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Specimens investigated

Lysiotyles scandens Benth., Guyana: Tutin 415 (RB41123)

Lysiotyles scandens Benth., Guyana: Scromburg 491 (L2732359)

Lysiotyles scandens Benth., Guyana: Steyermark 88128 (U1232626)

Additional information

Funding

This work was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.