Drosera sessilifolia Saint-Hilaire (1826: 259)

Gonella, Paulo Minatel, Sano, Paulo Takeo, Rivadavia, Fernando & Fleischmann, Andreas, 2022, A synopsis of the genus Drosera (Droseraceae) in Brazil, Phytotaxa 553 (1), pp. 1-76 : 57-58

26. Drosera sessilifolia Saint-Hilaire (1826: 259) . Figures 5c , 20g –i

Lectotype (designated here):— BRAZIL. Minas Gerais: Marais près Tapeira dans le Desert du Rio de St. Francisco, province des Minas [marsh near Tapeira (current district of Andrequicé, municipality of Três Marias) in the desert of St. Francisco River , Minas Gerais], s.d., Saint-Hilaire B1-1805bis (P-706174 !; isolectotype P-706175!).

≡ Drosera sessiliflora A.St. -Hil. ex Don (1831: 344) nom. inval. (orthographical variant)

= Drosera dentata Bentham in Hooker (1842: 105).

Lectotype (designated here):— GUYANA. 1836, Schomburgk 102 (K-000432530!; isolectotypes G-00301947 image!, G-00301948 image!, K-00432531!, P-00706173!, U-0001637 image!, US-00100646!).

= Drosera sessilifolia var. β Planchon (1848: 189) nom. inval.

= Drosera sessilifolia var. γ Planchon (1848: 190) nom. inval.

Annual, rosetted, acaulescent (sometimes with short fragile column towards the end of the growing season). Leaves semi-erect or decumbent, with entire-involute vernation; petiole gradually broadening into lamina; lamina obovate, with conspicuous unifacial marginal glands (“snap-tentacles”) on the marginal apex, and densely minutely glandularpilose on both surfaces; stipules rectangular in outline, fimbriate. Scapes erect at the base, glabrous, with a ceraceous appearance; sepals glandular-pilose; petals pink; ovary 5-merous, styles 5, entire, stigmata with long papillae. Seeds ovoid, black, testa reticulate.

Illustrations: — Saint-Hilaire (1826: t. XXV, figs.A & 1—habit and gynoecium); Eichler (1872: t. 90, fig. I—habit and details); Hoehne (1915: t. 124, fig. 1—habit and details); Diels (1906: 74, figs. 27A–D—leaf, calyx and gynoecium); Silva & Giulietti (1997: 84, fig. 5); Duno de Stefano & Culham (1998: 701: fig. 557—habit, leaf and calyx).

Distribution: —Widely distributed across South America: Venezuela, Guyana, Colombia, Brazil (North: AM, PA, RR, TO; Northeast: AL, BA, CE, MA, PB, PE, PI, RN, SE; Central-West: GO, MS, MT; Southeast: MG; Fig. 5c ), and Bolivia.

Habitat: — Seasonally wet areas in savanna vegetation of the Cerrado and Amazon domains, such as the margins of veredas and springs, as well as on coastal sandy plains (restingas) of the Atlantic Forest domain. It has also been recorded from campos rupestres in the Chapada dos Veadeiros, Goiás [Rivadavia & Batista 2622 ( SPF)]. The species grows in sandy to peaty soils, rarely over iron-rich deposits on clayish red soils. Found from sea level up to ca. 1200 m a.s.l.

Phenology:— Drosera sessilifolia presents different flowering periods across its distribution, usually from October to February in the northern range ( Guyana Shield) and from (April) June to October in Northeast and Central-West Brazil. The species usually flowers during the dry season, dying from drought as a monocarpic plant (hapaxanthic) after having produced multiple flowering scapes, generally surviving the dry seasons exclusively as dormant seeds that germinate early in the following wet season (hence the only true therophyte among the Brazilian Drosera species).

Conservation status: —Least Concern (LC). Widespread in Brazil and South America ( Brazil: AOO= 356 km 2, EOO= 5,214,713 km 2; global: AOO= 524 km 2, EOO= 6,484,228 km 2). It has been recorded from numerous National Parks across Brazil: Campos Ferruginosos (PA; Mota 2017), Chapada das Mesas (MA; Oliveira et al. 2018), Chapada dos Veadeiros (GO), Grande Sertão Veredas (MG/BA), Lençóis Maranhenses (MA), Pantanal (MS), Serra da Capivara (PI), and Sete Cidades (PI); as well as two State Parks: Araguaia (MT) and Jalapão (TO).

Notes: — Drosera sessilifolia is unique in the Americas as the only hapaxanthic (= monocarpic annual) species of the genus, and for the gynoecium structure: 5-merous, 5 undivided styles, and papillose stigmas (Fig. 20i; vs. 3- merous, 3 styles bifurcated at base resulting in 6 stigmatic tips, stigmata simple, bifid or flabellate in all other species), placing it in Drosera sect. Thelocalyx (sensu Fleischmann et al. 2018a) .

The species is highly homogeneous morphologically across its range, varying only in leaf size and coloration. Drosera sessilifolia is the second most widespread species in Brazil after D. communis .

Don (1831) misspelled the epithet ( Drosera sessiliflora ) creating an orthographical variant, which constitutes an invalid name under Art. 61 ( Turland et al. 2018).

Drosera dentata was described based on the specimen Schomburgk 102 without specifying where the type was deposited. Duplicates of that gathering are found in several herbaria, thus all constituting syntypes. Here, we select one of the specimens held at K as the lectotype, as it is the most completely preserved specimen among all examined duplicates.

Planchon (1848) described two varieties for D. sessilifolia , however, using single Greek letters to name them, making such names invalid according to ICN Art. 32.1 ( Turland et al. 2018). Notwithstanding, such varieties are of no taxonomic relevance as they merely represent the size variation within this taxon.

Selected specimens examined: — BRAZIL. Alagoas: Piaçabuçu, 20 August 2006, Rodrigues 2018 (MAC). Amazonas: Humaitá, 500 m ao norte da BR-230, km 2, 16 January 1980, Janssen 156 (INPA, RB). Bahia: Coribe, 16 June 2006, Rivadavia 2223 (SPF). Ceará: 4 km north of Soure (Caucaia), July 1945, Cutler 8388 (NY). Goiás: Alto Paraíso de Goiás, Chapada dos Veadeiros, 23 June 2007, Rivadavia & Batista 2622 (SPF). Serra do Morcego, córrego Estrema, ca. 38 km NE of Formosa, 21 April 1966, Irwin et al. 15189 (NY, UB). Maranhão: Barreirinhas, Lençóis Maranhenses, 30 March 2007, Rivadavia 2494 (SPF). Mato Grosso: Giráu-Caceres, August 1908, Hoehne 149 (R, US); Novo Santo Antônio, Parque Estadual do Araguaia, 08 June 2005, Jaconski et al. 199 (UB). Mato Grosso do Sul: Corumbá, Baía Bonita, Pantanal, 28 July 1992, Rivadavia 142 (SPF). Minas Gerais: Arinos, 29 April 1999, Rivadavia & Sato 965 (SPF). Brasilândia de Minas, fazenda Brejão, 14 July 2000, Lombardi 4018 (BHCB). Pará: Without attribution to administrative area, 22 July 1916, Duck 16311 ( US). Paraíba: Mamanguape, Reserva Biológica Guaribas, 26 October 2012, Silva 26 (JPB). Pedras de Fogo, Fontainha, depois de Sta. Emília, 01 October 1962, Tavares 1060 ( US). Pernambuco: Goiana, Eng. Calingi, 05 September 1967, Lima s.n. (IPA-16608). Piauí: Piracuruca, Parque Nacional de Sete Cidades, 27 July 2009, Mendes & Annunziata 583 (UB, TEPB). Without attribution to administrative area, s.d., Gardner 2480 ( US). Rio Grande do Norte: Rio do Fogo, Lagoa da Cotia, 11 October 2015, Garcia & Gonçalves 53 (UFRN). Roraima: Estrada Manaus-Boa Vista, between Mucajaí & Boa Vista, 21 November 1977, Steward et al. 145 (INPA, NY). Sergipe: Pirambu, June 2013, Carregosa & Santos 402 (ASE). Tocantins: Santa Rosa do Tocantins, Folha SC-23-Y-C, 07 July 2009, Oliveira et al. 1589 (HUEFS, IBGE, UB).

Figures

FIGURE 5. Distribution maps of Drosera species with broad distribution ranges in Brazil. a, D. latifolia. b, D. montana. c, D. sessilifolia.