Commelina diffusa Burm.f., Fl. Indica 18: pl. 7, f. 2. 1768.

Pellegrini, Marco Octavio de Oliveira & Forzza, Rafaela Campostrini, 2017, Synopsis of Commelina L. (Commelinaceae) in the state of Rio de Janeiro, reveals a new white-flowered species endemic to Brazil, PhytoKeys 78, pp. 59-81 : 60-61

2. Commelina diffusa Burm.f., Fl. Indica 18: pl. 7, f. 2. 1768. Fig. 1B

Commelina communis Vell., Fl. Flumin.: 30, 1829, nom. illeg. non C. communis L., Sp. Pl. 1: 40, 1753. Lectotype (designated here). [illustration] Original parchment plate of Flora fluminensis in the Manuscript Section of the Biblioteca Nacional do Rio de Janeiro [mss1095062_079] and later published in Vellozo, Fl. flumin. Icon. 1: t. 75. 1831. Syn. nov.

Holotype.

INDIA. Coromandel, s.dat., D. Outgaerden s.n. (G barcode G00360106!).

Selected specimens seen. BRAZIL. Rio de Janeiro: Arraial do Cabo, 24 Jul 1953, F. Segadas Vianna 1157 (R, US). Casimiro de Abreu, Barra de São João, 27 May 1953, F. Segadas Vianna 347 (R, US). Guapimirim, trilha das andorinhas, 20 Dec 1995, L.A. Lira Neto 161 (RB). Itaboraí, entre os rios Caceribu e Macacu, 10 Aug 2007, A. Rodarte 4Cf (RB). Itatiaia, Parque Nacional do Itatiaia, Hotel Repouso, 14 Dec 1997, J.M.A. Braga 4539 (RB). Mangaratiba, Reserva Ecológica Rio das Pedras, trilha para o mirante, 12 Jul 1997, J.A. Lira Neto 603 (RB). Niterói, Jurujuba, 16 Jan 1959, A. Castellanos 22336 (R). Petrópolis, Serra da Estrela, meio da Serra, antigo leito da estrada de ferro, próximo ao Poço do Cipó, 9 Mar 1978, P.P. Jouvin 121 (RB). Resende, margem da rodovia Dutra, Km 302 sentido RJ, ao lado da Light, próximo ao Rio Paraíba do Sul, 9 Jun 2012, M.O.O. Pellegrini et al. 232 (RB). Rio de Janeiro, Urca, 10 Jan2012, M.O.O. Pellegrini et al. 182 (RB). São João da Barra, 30 May 1953, F. Segadas Vianna 428 (R, US). Silva Jardim, próximo à sede da REBIO, 29 Oct 1997, J.A. Lira Neto 714 (RB). Teresópolis, Laje, estrada para Campo Limpo, Granja Mafra, 28 May 1977, L.D.A. Freire de Carvalho 600 (RB).

Distribution and habitat.

Tropical and subtropical regions of the world, being very common in shady disturbed areas such as road sides, gardens and forest margins, and in agricultural fields. It is also found growing on the edge of wet paddy fields, ponds, ditches and stream sides (Fig. 2 ).

Phenology.

Throughout the year, but especially in the rainy season.

Conservation status.

Following the IUCN recommendations ( IUCN 2001), it should be considered as Least Concern (LC) in the state of Rio de Janeiro and worldwide.

Morphological notes.

The specimens from the state of Rio de Janeiro usually show a staminode malformation, i.e. the central antherode is lacking in most of the herbaria and living specimens examined.

Nomenclatural and taxonomical notes.

Commelina communis Vell. is a later homonym of C. communis L. (the genus’ type species), thus, rendering it illegitimate. Vellozo’s description (1929) is little informative, especially for Commelina , lacking all the characters evidenced by Faden (2008) as important to delimitate species in the genus. Despite this, the spathe and flower details ( Vellozo 1831: t. 75), along with the leaf shape and stem diagnosis (Vellozo 1929), make it possible to associate C. communis Vell. to C. diffusa , rather than to C. deficiens Herb. (= C. erecta ), as pointed out in the Index Methodicus of Flora fluminensis ( Vellozo 1831, v. 1).

Figures

Figure 1. Commelina in the state of Rio de Janeiro. A C. benghalensis L. B C. diffusa Burm. f. C-D C. erecta L.: C detail of the inflorescence showing aborted upper cincinnus D flower E-F C. obliqua Vahl: E detail of the inflorescence showing the two developed cincinni F flower G C. rufipes var. glabrata (D. R. Hunt) Faden & D. R. Hunt H-I C. rufipes var. rufipes Seub.: H detail of the leaf-sheaths, showing the hirsute rusty hairs I mature fruits. G by Flora Virtual Estacion Biologica El Verde group, remaining field photos by M. O. O. Pellegrini.

Figure 2. Distribution map of Commelina in the state of Rio de Janeiro. Crosses C. benghalensis green dots C. diffusa var. diffusa; blue dots C. erecta; stars C. obliqua; empty square C. rufipes var. glabrata; full squares C. rufipes var. rufipes.