Drosera tentaculata Rivadavia (2003: 79)

Rivadavia, Fernando, Gonella, Paulo Minatel, Sano, Paulo Takeo & Fleischmann, Andreas, 2014, Elucidating the controversial Drosera montana complex (Droseraceae): a taxonomic revision, Phytotaxa 172 (3), pp. 141-175 : 159-162

Drosera tentaculata Rivadavia (2003: 79) ( Figs. 5 , 8 , 9 )

Type: — BRAZIL. Minas Gerais: Diamantina, no alto da cachoeira dos Cristais, estrada para Biribiri , c. 1000 m alt., 31 July 2002, Rivadavia & Gibson 1376 (holotype SPF!) .

Description: —Perennial rosetted herbs, often forming short upright or prostrate stems up to 2.5 cm in length, densely covered by persistent dead leaves. Roots slightly succulent, sparsely branched, black, densely covered with root hairs. Indumentum consists of white eglandular trichomes (pale brown when dried), on the abaxial leaf surface, more rarely on the adaxial petiole surface and base of the scape; capitate glandular trichomes on scape, bracts, pedicels and sepals; and minute sessile glands ca. 0.03 mm in diameter on leaves and inflorescence parts. Leaves 3–13(–17) mm long, with geniculate vernation, decumbent, obovate to obovate-cuneate to cuneate, apex obtuse to sub-truncate, orangered to deep red in exposed habitats, green in shadier habitats, usually bicolored with the petiole greener than the lamina; petiole 0.5–4(–8) mm long, 0.8–1.5 mm wide, abaxial surface sparsely (rarely densely) eglandular-pilose adaxial surface glabrous to sparsely eglandular-pilose; lamina 2–9 mm long, 1.5–4(–6.5) mm wide, abaxial surface glabrescent, eglandular trichomes concentrated on basal lateral margins, adaxial surface covered with numerous red, motile, capitate tentacles with radial symmetry, the apical tentacles conspicuously distinct, 7–9(–12) in number, 4– 9 mm long, stalk horizontally flattened and narrowly-obcuneiform in shape, 0.4–0.5(–0.6) mm wide at base, the head linearly-rectangular, 0.7–1.2(–1.5) mm long with unifacial gland tip; stipules 2–4 mm long, 0.8–1.5 mm wide, rectangular, membranaceous, translucent white in color (drying bronze colored), apical 1/2–2/3 divided into 3 segments, the lateral ones longer, narrower, poorly divided or entire, the central one shorter, broader, and with fimbriate apex. Scapes 1–3, erect from the base, 30–160(–185) mm long (including floriferous part), terete, green to deep red in color, erect from the base, glandular trichomes present from the base, somewhat uniform in size and increasing in density towards apex, usually sparsely eglandular-pilose on lower third of the scape; inflorescence a scorpioid cyme bearing (1–)2–8(–10) flowers, never bifurcating; bracts caducous, usually absent on mature scapes, 1–2.5 mm long, linear, densely glandular-pilose abaxially; pedicels 0.7–5(–10) mm long, inserted 2–20 mm apart, densely glandular-pilose; sepals 5, 2– 4.5 mm long, 0.7–2 mm wide, oblong-ovate, rarely ovate, united at basal 1/3 of length, apex acute, densely glandular-pilose abaxially; petals 5, 5.5–8.5 mm long, 3–4 mm wide, obovate, light to dark pink in color; stamens 5, 2.5–4 mm long, filaments white to light pink, anthers 1–1.6 mm long, bithecate, yellow; ovary 3-carpellate, fused, 1–1.7 mm in diameter, globose, subglobose to slightly trilobed in outline; styles 3, forked at the base, 2–4 mm long (including stigmata), pale pink in color, style arms curving inwards at the end of anthesis, stigmata indistinct, bilobed, basally bifurcate, or simply thicker than the style; fruit a dry dehiscent capsule, 2–2.5 mm long, ellipsoid, 3-valvate; seeds 0.3–0.45 mm long, 0.15–0.2 mm wide, ovoid-ellipsoid, black, testa reticulate.

Illustrations: —Rivadavia (2003: 80, fig. 1).

Distribution and ecology: — Drosera tentaculata is endemic to the Espinhaço Range ( Fig. 5 ), occurring in Minas Gerais from the Serra do Cipó in the south to Itacambira in the north, and again disjunctly over 400 km to the north at the Chapada Diamantina in central Bahia (Rio de Contas, Piatã, and Catolés). It is especially abundant at the Serra do Cipó and on the Diamantina Plateau, which correspond to the core distribution area of this species, where large and dense populations are commonly observed. In other regions (Itacambira, Serra do Cabral, Chapada Diamantina) D. tentaculata is only know from small and scattered populations, and it is possibly also present on any of the numerous and still poorly explored mountains between Itacambira and the Chapada Diamantina.

Drosera tentaculata occurs in campo rupestre vegetation in montane to high-montane habitats, at elevations between 800–1600 m, where it is usually found in fine white sand with quartz gravel ( Fig. 8A ), but also on peatysandy soil, in cracks on sandstone ( Fig. 8B ), or over a thin layer of soil over sandstone. During the summer wet season, frequent rainfalls keep D. tentaculata habitats humid, but these become desiccated during the winter dry season, which coincides with the flowering period of this species. At a few sites on the Diamantina Plateau D. tentaculata was observed growing in year-round flooded areas, where it can present more robust rosettes with longer and wider leaves bearing a few extra apical tentacles (these exceptional sizes and numbers are given in parentheses in the description). Drosera tentaculata was found growing sympatric with D. ascendens , D. camporupestris , D. chrysolepis , D. montana , D. quartzicola , D. schwackei , D. spiralis , D. spirocalyx , and D. tomentosa (both varieties).

Phenology: — Drosera tentaculata flowers primarily in the dry season, extending to the beginning of the wet season, between July and October.

IUCN Red List Category: — Drosera tentaculata is widespread along the Espinhaço Range and especially common in the southern part of its range. Because it is protected by national and state parks, D. tentaculata is here considered of Least Concern (LC), according to the criteria of the IUCN Red List ( IUCN 2001).

Discussion: — Drosera tentaculata can be distinguished by its obovate, obovate-cuneate or cuneate leaves with 7–9(–12) conspicuous apical retentive tentacles 4–9 mm long, 0.4–0.5(0.6) mm wide at the base, each with a narrowlyobcuneiform stalk and a linearly-rectangular head 0.7–1.2(–1.5) mm long. Furthermore, it differs from other taxa in this complex by the usually longer styles (up to 4 mm vs. up to 3 mm in the others), and less differentiated stigmata.

A closer inspection of leaf vernation has revealed what is one of the most distinguishing features of D. tentaculata from other members of the species complex. In D. montana , D. spirocalyx , D. tomentosa , and other Brazilian tetraploid Drosera taxa, the developing leaf is rolled coil-like in bud and unfurls like a fern frond as it matures, representing circinate vernation. More common among taxa of Drosera sect. Drosera is geniculate-involute vernation, where the lamina is folded once over the petiole, and the leaf margins are folded inwards at an acute angle towards the apex of the leaf. In D. tentaculata the vernation has been found to be geniculate, with the apical tentacles initially bent flat against the lamina, and the lamina folded once over the petiole (see Fig. 8E ), yet the margins of the lamina are not folded inwards. This gives the young lamina of D. tentaculata a semi-circular shape, instead of the typical triangular shape seen in geniculate-involute vernation. This mode of leaf vernantion is unique among this species affinity, and it is likely to be correlated with the exceptionally large unifacial tentacles (“snap tentacles”) present in D. tentaculata .

In plants from Serra do Cipó, Minas Gerais, Rivadavia (2003) reported and illustrated styles with constrictions. Several specimens were re-analyzed for the current study and this characteristic was not observed in any plant from that region or any other area. Thus, the depicted styles with constrictions were possibly based on malformed or unripe structures.

In previous floristic studies, D. tentaculata was referred to as D. montana var. montana ( Silva, 1994; Silva & Giulietti, 1997), probably due to the glabrous to sparsely eglandular-pilose base of the peduncle.

Specimens examined: — BRAZIL. Bahia: Município de Piatã, estrada para Inúbia, 16 July 2005, Rivadavia et al. 2033 (SPF), 01 August 2012, Gonella et al. 534, 538 (SPF). Município de Rio de Contas, lower NE slopes of the Pico das Almas, 17 February 1977, Harley et al. 19568 (SPF); Pico das Almas, Campo do Queiroz, 11 November 1988, Harley et al. 26353 (SPF); trilha subindo o Pico das Almas, 17 July 2005, Rivadavia et al. 2052 (SPF); trilha para o alto do Pico do Itobira, 18 July 2005, Rivadavia et al. 2070 (SPF). Minas Gerais: Município de Buenópolis, alto da Serra do Cabral em direção ao Brejo Grande, 03 July 2003, Rivadavia & Menezes 1651 (SPF); Parque Nacional das Sempre Vivas, próximo ao alojamento de guarda-parques, 04 September 2011, Gonella et al. 449 (SPF), Gonella et al. 456 (SPF). Município de Diamantina, 03 June 1986, Brandão 11688 (PAMG); Planalto, 15 July 1970, Duarte 12983 (BHCB); campus II da UFVJM, 29 August 2005, Nunes & Costa 8 (DIAM); 11 December 2007, Vasconcelos et al. 2 (DIAM); 16 km de Diamantina para Mendanha, 06 July 1996, Souza et al. 11952 (SPF); estrada para Mendanha, 10 August 2010, Gonella et al. 353 (SPF); 12 October 1984, Mello-Silva et al. CFCR 5379 (SPF); estrada para Conselheiro Mata, 23 September 1994, Splett 638 (UB), 29 November 2000, Prata et al. 1035 (SP); estrada Guinda-Conselheiro Mata, 25 July 1998, Hatschbach et al. 68266 (SPF); estrada que sai do Bairro Arraiola, 08 February 2008, Gonella & Viana 216 (SPF); ao sul da cidade, 24 July 2008, Gonella et al. 165 (SPF), 24 July 2008, Albuquerque et al. 4 (UB), 25 July 2008, Gonella et al. 173 (SPF), 25 July 2008, Albuquerque et al. 6 (UB); estrada para Curvelo, 27 February 1997, Rivadavia & Pinheiro 571 (SPF); estrada para Tapetes Arraiolos, 27 February 1997, Rivadavia & Pinheiro 580 (SPF), 10 July 1999, Rivadavia, et al. 1106 (SPF); estrada Diamantina-Conselheiro Mata, 29 June 2003, Rivadavia 1630 (SPF); estrada para Barão de Guacuí, 11 May 2007, Rivadavia 2518 (SPF); estrada para a Gruta do Salitre, 13 May 2007, Rivadavia 2542 (SPF); estrada para Milho Verde, 13 May 2007, Rivadavia 2555 (SPF); trilha dos Escravos, 10 August 2010, Gonella et al. 342 (SPF); Biri-Biri, cachoeira dos Cristais, 07 July 1995, Rivadavia & Pinheiro 451 (SPF), 31 July 2002, Rivadavia & Gibson 1376 (SPF; type); Biri-Biri, ao lado da estrada, 10 August 2010, Gonella et al. 343 (SPF); Biri-Biri, Cachoeira da Sentinela, 10 August 2010, Gonella et al. 346 (SPF); São João da Chapada, estrada para Macacos, 04 September 2011, Gonella et al. 425 (SPF), 04 September 2011, Gonella et al. 435 (SPF). Município de Gouveia, estrada Diamantina-Curvelo, 02 August 2002, Rivadavia & Gibson 1402 (SPF), 06 April 2003, Rivadavia 1591 (SPF), 03 September 2011, Gonella et al. 424 (SPF). Município de Itacambira, estrada para Montes Claros, 05 March 1997, Rivadavia 614 (SPF), 14 July 1999, Rivadavia & Pinheiro 1143 (SPF), 29 July 2002, Rivadavia & Gibson 1364 (SPF), 22 April 2010, Gonella et al. 287 (SPF), 13 February 2011, Gonella et al. 401 (SPF). Município de Jaboticatubas, Serra do Cipó, km 142 da rodovia Lagoa Santa-Conceição do Mato Dentro, 27 May 1972, Joly et al. CFSC 2111 (SP); estrada da usina, 21 August 1972, Joly & Semir CFSC 3067 (SP); km 138-9 rodovia Lagoa Santa-Conceição do Mato Dentro, 08 September 1972, Joly & Müller CFSC 3433 (SP); 10 April 1980, Barros 200 (SP); trilha para mirante do canyon Bocaina, 05 June 1994, Rivadavia 289 (SPF); Fazenda da Serra do Cipó, 11 September 1994, Rivadavia 305 (SPF); estrada para o mirante do canyon Bocaina, 23 February 1996, Rivadavia & Mullins 541 (SPF, MO); km 112-113 da estrada para Conceição do Mato Dentro, 09 July 1999, Rivadavia, et al. 1096 (SPF); km 112 da MG-10, 12 November 2007, Gonella et al. 54 (SPF), 12 November 2007, Gonella et al. 55 (SPF); trilha do Travessão, 22 July 2008, Albuquerque 22 (UB), Albuquerque 25 (UB). Município de Joaquim Felício, alto da Serra do Cabral, 07 March 1997, Rivadavia 629 (SPF); entre Joaquim Felício e Francisco Dumont, 03 July 2003, Rivadavia 1662 (SPF), 04 July 2003, Rivadavia 1676 (SPF); entre Joaquim Felício e Augusto de Lima, 04 July 2003, Rivadavia 1672 (SPF). Município de Santana do Riacho, ao lado da represa, 20 June 1990, Brandão 17283 (PAMG); caminho da Lapinha, 11 February 1991, Arbo et al. 4851 (SPF); rodovia Belo Horizonte-Conceição do Mato Dentro, 06 September 1980, Forero et al. 7762 (SPF) (mixed collection with D. tomentosa var. tomentosa ); 2.5 km após acampamento Serra Morena, 28 July 2002, Rivadavia & Gibson 1362 (SPF); início da trilha para o Pico do Breu, 30 January 2005, Rivadavia 1944 (SPF); trilha para o Velozieto, 15 May 2008, Gonella et al. 84 (SPF), 08 August 2010, Gonella et al. 336 (SPF); km 112 da MG-10, trilha para o canyon Travessão, 19 April 2010, 16 May 2008, Gonella et al. 95 (SPF), Gonella et al. 98 (SPF), 20 July 2008, Gonella et al. 127 (SPF), Gonella et al. 135 (SPF), 22 July 2008, Gonella et al. 145 (SPF), Gonella et al. 154 (SPF), Gonella et al. 156 (SPF), Gonella et al. 161 (SPF), 06 April 2009, Gonella et al. 220 (SPF), 19 April 2010, Gonella et al. 261 (SPF), Gonella et al. 268 (SPF), 02 September 2011, Gonella et al. 421 (SPF). Município de São Gonçalo do Rio Preto, PERP, trilha para o Pico Dois Irmãos, 05 February 2009, Gonella & Viana 198 (SPF). Município de Serro, estrada para Gouvea, 11 October 1996, Marcondes-Ferreira et al. 1355 (UEC); Milho Verde, 24 July 2002, Mota 1643 (BHCB) (mixed collection with D. tomentosa var. glabrata ); trilha para a cachoeira do Arco-Íris, 05 April 2003, Rivadavia & Neves 1561 (SPF); planície ao lado da cidade, 05 April 2003, Rivadavia & Neves 1570 (SPF); estrada de Milho Verde para Capivari, 13 May 2007, Rivadavia 2557 (SPF).

Figures

FIGURE 5. Distribution map of D. spirocalyx (squares) and D. tentaculata (circles) in eastern Brazil.

FIGURE 8. Drosera tentaculata. A, habit. B, C, detail of the indumentum at the base (B) and apex (C) of the scape. D, leaf, adaxial surface. E, leaf, abaxial surface. F, stipule. G, calyx. H, petal. J, gynoecium and one stamen seen from above. K, seed.A–D and G–J based on the holotype; E based on Gonella et al. 127; K based on Gonella et al. 135. Drawn by P.M. Gonella.

FIGURE 9. Drosera tentaculata. A, habitat, in sandy soil with white quartz gravel at the Serra do Cipó, Minas Gerais. B, habitat, in cracks of sandstone, at Diamantina, Minas Gerais. C, rosette seen from above. D, detail of juvenile leaf, with seven differentiated apical tentacles. E, detail of the center of the rosette, showing the leaf buds. F, detail of flowers in post-anthesis, showing the calyx. G, flower. All by P.M. Gonella.