Pollen morphology of the Brazilian species of Dyschoriste Nees and Hygrophila R.Br (Ruellieae, Acanthaceae) and its taxonomic significance

Abstract

Acanthaceae is an eurypalinous and pollen morphology has been used in species delimitation and as a support to new taxa recognition. The aim of the present study is to provide new pollen descriptions for the Brazilian species of Dyschoriste (7 spp.) and Hygrophila (4 spp.). We analysed the pollen under light and scanning electronic microscopy. Pollen grains of D. erythrorhiza, D. eulinae, D. glandulifera, D. vinacea, H. acutangula, and H. paraibana are described here for the first time. Dyschoriste species has pollen grains medium to large, isopolar, prolate spheroidal, subprolate to prolate, circular, subcircular, and subtriangular amb, 3-colporate and 13–20-pseudocolpate and the exine is psilate-microechinate to perforate-microechinate. Hygrophila species has pollen grains small to medium, isopolar, oblate spheroidal, subcircular to subquadrangular amb, 4-colporate and 15–21-pseudocolpate and exine is perforate-reticulate. Palynological characters of high taxonomic relevance were: pollen size; pollen shape; length of colpi; endoaperture shape; sexine and nexine thickness; sexine ornamentation; number of pseudocolpi. From our results, a new combination is proposed, D. glandulifera, based on both pollen and macro morphology traits.

Keywords:

• eurypalinous
• Hygrophilinae
• Petalidiinae
• palynology
• plant systematics
• plant taxonomy

Acknowledgements

The authors thank the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for a scholarship granted to the first author; Centro de Apoio à Pesquisa from Universidade Federal Rural de Pernambuco (CENAPESQ–UFRPE) and Laboratório de Solidificação Rápida (LSR) – Centro de Tecnologia from Universidade Federal da Paraíba for SEM images of pollen grains; Technicians responsible for the SEM, Natan Pessoa and Isaque Jeônimo Porto; Laboratório de Ecologia Aquática and Laboratório de Ecofisiologia de Plantas Cultivadas for the space and equipment provided; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for Research Productivity Grant (PQ–2) to JIMM (Proc. No. 303180/2019-6); Thomas F. Daniel for language revision and decision support; Anderson S. Pinto for support with statistical analyses.

Disclosure statement

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

Specimens investigated

Dyschoriste erytrhorhiza (Nees) Lindau. Brazil: Minas Gerais, J.A. Lombardi; A. Salino 1719, 23 May 1997 (BHCB).

Dyschoriste eulinae F.K.S. Monteiro & J.I.M. Melo. Brazil: Paraíba, F.K.S. Monteiro 274 & A.S. Pinto, 28 August 2020 (HACAM).

Dyschoriste glandulifera (Nees) F.K.S. Monteiro & J.I.M. Melo. Brazil: Minas Gerais, A. Macedo 1072, 16 May 1948 (RB).

Dyschoriste hygrophiloides (Nees) Kuntze. Brazil: Paraná, G. Hatschbach; M. Hatschbach; V. Nicolack 53626, 18 November 1989 (MBM).

Dyschoriste lavandulacea (Nees) Kuntze. Brazil: Goiás, A. Macedo s.n., 07 December 1949 (RB66214).

Dyschoriste trichanthera Kobuski. Brazil: Brazil: Mato Grosso do Sul, G. Hatschbach; J.M. Silva 49193, 17 March 1985 (MBM).

Dyschoriste vinacea F.K.S. Monteiro & J.I.M. Melo. Brazil: Paraíba, F.K.S. Monteiro 273 & A.S. Pinto, 2 August 2020 (HACAM).

Hygrophila guianensis Nees in Bentham. Brazil: Rio Grande do Sul, D.B. Falkenberg; J.R. Stehmann; A.O.S. Vieira 6552, 23 January 1994 (FUEL).

Hygrophila costata Nees & T. Nees. Brazil: Paraná, J.T. Motta 2329, 25 January 1992 (FUEL).

Hygrophila acutangula Nees ex Mart. Brazil: Rio de Janeiro, C.P. Bore 1548, s.d. (RB).

Hygrophila paraibana Rizzini. Brazil: Paraíba, L.P. Félix 12043, 22 November 2007 (EAN).

Additional information

Funding

This work was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico: Research Productivity Grant (PQ-2) to JIMM (Proc. No. 303180/2019-6); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior: Scholarship granted for first author (Proc. No. 88882.436295/2019-01).