Drosera spiralis Saint-Hilaire (1826: 270)

Gonella, Paulo Minatel, Rivadavia, Fernando & Sano, Paulo Takeo, 2012, Re-establishment of Drosera spiralis (Droseraceae), and a new circumscription of D. graminifolia, Phytotaxa 75 (1), pp. 43-57 : 49-53

Drosera spiralis Saint-Hilaire (1826: 270) . Figs. 4 , 5 .

Type:— BRAZIL. Minas Gerais: “Crescit in montibus dictis Serra de Curumatahy , ad rivulum Corgo Novo, in parte provinciae Minas Geraes dicta Distrito dos Diamantes; alt. circiter 3700. Inveni Septembre cum fructibus”, Saint- Hilaire s.n. (holo P!) .

Drosera brasiliensis Martius ex Eichler (1872: 396) , nom. inval., syn. nov.

Illustrations:— Eichler [1872: t. 91, II (as D. graminifolia )]; Silva [1994: 51, fig. 9 (as D. graminifolia )]; Silva & Giulietti [1997: 86, fig. 6 (as D. graminifolia )]; Correa & Silva [2005: 40, fig. 24A–E (as D. graminifolia )].

Perennial rosetted herbs, acaulescent or forming short stems up to 10 cm long, covered by persistent dead leaves. General indumentum consists of white eglandular hairs 0.5–1.5 mm long, minute sessile glands c. 0.03 mm in diameter, and glandular capitate trichomes 0.1–0.5 mm long (each of these often bearing a dried droplet of a translucent-yellow secretion in herbarium specimens). Leaves 75–350 mm long, with irregular circinate vernation, erect to semi-erect, patent when old, linear, spirally twisted when dead, apex aciculate, ending in a single tentacle; petioles 5–30 mm long, 1–3 mm wide, green in color, glandular pilose on both surfaces, abaxially only along the margins and adaxially absent near the very base, sparse eglandular hairs along the margins, semicircular to transversely elliptic in cross section; lamina 70–320 mm long, 0.6–2.8 mm wide, green, yellowish-green or reddish-green in color (especially towards the apex), adaxial surface covered with numerous red, carnivorous, capitate tentacles, abaxial surface densely glandular and eglandular pilose; stipules 14–22(–30) mm long, 8–22 mm wide at the base, triangular, membranaceous, patent when old, bronze-gold in color, apex acute, fimbriate or entire. Scapes 1–2 per plant, 110–430 mm long (including inflorescences), 0.6–3 mm in diameter at the base, base erect; inflorescence a scorpioid cyme, often bifurcate to multiply branched (up to 8 times), occasionally with 1–3 larger sterile bracts at the base, bearing 5–78(–90) somewhat congested flowers, indumentum of the scape, pedicels, abaxial surfaces of bracts and sepals consisting of eglandular hairs, glandular capitate trichomes, and sessile glands; bracts 2.5–4 mm long, lanceolate, usually absent; pedicels 1–7.5 mm long, inserted 1.5–7 mm apart from each other; sepals 5, 4.5– 7.5 mm long, 1.5–2.2 mm wide, oblong-lanceolate to lanceolate, united at basal 1/3–1/4 of length, often bearing 1–several emergences similar to the tentacles found on the lamina; petals 5, 6– 10 mm long, 5–7.5 mm wide, obovate to obovate-cuneate, light to dark pink-lilac in color, rarely white; stamens 5, 4– 6 mm long, anthers 1–1.6 mm long, bithecate, yellow; ovary 3-carpellate, 1–1.5 mm in diameter at anthesis, globose, slightly 3-lobed in outline; styles 3, forked at the base to 1/3 of length, 3–4.5 mm long (including stigmata), stigmata flabellate, pink-lilac in color. Fruit a dry capsule, c. 3 mm long, ellipsoid, 3-valvate. Seeds ovoid, 0.6–0.65 mm long, 0.25–0.3 mm wide, testa reticulate, black.

Distribution and ecology:— Brazil, endemic to the central and northern parts of the Serra do Espinhaço, in Minas Gerais state. Drosera spiralis has a disjunct distribution, occurring on the Diamantina Plateau in the municipalities of Diamantina, Serro, Couto de Magalhães de Minas, Rio Vermelho, São Gonçalo do Rio Preto, Buenópolis, and—after a gap of approximately 100 km —on the Northern Mountains Complex of the Espinhaço Range ( Echternacht et al. 2011), in the municipalities of Itacambira, Botumirim, and Grão Mogol ( Fig. 1 ).

Drosera spiralis is common in campo rupestre vegetation of montane regions at elevations between 700 and 1500 m. It is very resistant to soil desiccation, often growing in exposed habitats that become parched during the winter dry season. On the Diamantina Plateau , D. spiralis is usually found in small and scattered populations along seasonal streams and seepages, in sandy soils mixed with peat, or in cracks of quartzitic sandstone, at elevations between 800 and 1500 m. At the Northern Mountains Complex, D. spiralis commonly forms larger populations in the same habitats and also in perennial boggy seepages ( Fig. 5A ), or more rarely along the margins of perennial rivers over quartzitic sandstone ( Fig. 5C ) at elevations between 700 and 1350 m.

Healthy D. spiralis plants are often found in full bloom at the height of the dry season, suggesting that they are quite capable of avoiding desiccation in water-stressed habitats. Condensation at night is possibly the main source of water for D. spiralis during the dry season, and the thick mass of dried black leaves often surrounding the base of each plant may help in concentrating and retaining moisture.

Drosera spiralis commonly grows sympatric with D. tomentosa Saint-Hilaire (1826: 261) , but has also been observed on rarer occasions with D. ascendens Saint-Hilaire (1826: 268) , D. camporupestris Rivadavia (2003: 85) , D. chrysolepis Taubert (1893: 505) , D. communis Saint-Hilaire (1824 : t. XV(1)), D. graomogolensis Silva (1997: 85) , D. hirtella Saint-Hilaire (1826: 262) var. hirtella , D. montana Saint-Hilaire (1826: 260) , D. tentaculata Rivadavia (2003: 79) , D. grantsaui Rivadavia (2003: 82) , D. × fontinalis Rivadavia (2009: 121), as well as various species of the also carnivorous genera Genlisea Saint-Hilaire (1833: 428) and Utricularia Linnaeus (1753: 18) (Lentibulariaceae) .

Phenology: — Drosera spiralis can be found with flowers and in fruit the year round, but the main flowering period occurs during the dry season, from April to December.

Conservation Status: — Drosera spiralis has a large area of occurrence and is safeguarded by several Protection Areas, State Parks (Rio Preto, Grão Mogol), and a recently created National Park (Sempre-Vivas). It is thus here considered of Least Concern (LC) according to the IUCN (2001) categories and criteria.

Notes: — Rivadavia (1996) suggests that plants from the northern range of D. spiralis could be classified as a distinct subspecies, based mainly on their more robust habit. This variation in the leaf size is exemplified in Fig. 4 , which depicts: the shorter petiole commonly observed in plants from the southern range ( Fig. 4C ), as well as the long petiole more common in plants of the northern range ( Fig. 4D ). Albeit the recorded extremes in leaf length, a continuum of variation is clear when comparing plants across the distribution range, and no other distinctive characters were observed for the northern populations which would justify separation as a distinct taxon at subspecific or varietal rank.

Drosera spiralis is the only species of the genus known to have tentacle-like emergences on the sepals as a common occurrence—and not as an anomaly ( Fig. 4G , 5E ). Also, large sterile bracts resembling diminutive rosette leaves, often with tentacles and even small stipules, are occasionally observed neat the apex of the scape and at the base of the inflorescence of D. spiralis . A few of these anomalous plants at different populations on the Diamantina Plateau were even observed to have their sepals transformed into minute carnivorous leaves.

White-flowered specimens of D. spiralis were observed at Grão Mogol (Rivadavia 295), but the plants had red-pigmented tentacles on the leaves, thus not representing a form entirely lacking red phytopigments.

The entry labeled as D. graminifolia in the phylogenetic study of Rivadavia et al. (2003) corresponds to D. spiralis , as do both accessions used by Rivadavia (2005) to determine chromosome numbers.

Specimens Examined: — BRAZIL. Minas Gerais: Município de Botumirim, Rio do Peixe , 10 February 2011, Gonella et al. 372 ( SPF) , 06 September 2011, Gonella et al. 477 ( SPF) , 06 September 2011, Rivadavia 2704 ( SPF) ; Alto da Serra da Canastra , 15 June 1991, Mello-Silva et al. 513 ( SPF) , 19 November 1992, Mello-Silva et al. 672 ( BHCB, SPF) , 13 October 2001, Rivadavia 1270 ( SPF) ; Serra da Canastra , 20 December 1994, Rivadavia 333 ( SPF) , 20 November 2007, Forzza et al. 4943 ( RB, SPF) . Município de Buenópolis , Parque Nacional das Sempre-Vivas, 04 September 2011, Gonella et al. 453 ( SPF) . Município de Couto de Magalhães de Minas, 40 km leste de Diamantina , 12 May 2007, Rivadavia 2533 ( SPF) ; Chapada do Couto , 12 July 1984, Furlan et al. CFCR 4647 ( SPF) . Município de Diamantina , 13 January 1947, Egler 322 ( RB) ; açude, 11 November 1937, Mello-Barreto 10098 (R); ao sul da cidade, 24 July 2008, Gonella et al. 164 ( SPF) , 171 (SPF); Campus II da FAFEID, 03 September 2004, Costa & Lessa 805 ( DIAM, HUEFS, SPF) ; Campus II da UFVJM, 29 August 2005, Nunes & Costa 11 ( DIAM) ; Campus JK da UFVJM, 10 September 2008, Andrino & Costa 11 ( DIAM) ; c. 4km ao sudeste da cidade, 13 May 2007, Rivadavia 2543 ( SPF) ; Distrito de São João da Chapada, estrada para Macacos , 04 September 2011, Gonella et al. 436 ( SPF) ; Estrada para Biri-Biri , 05 June 1985, Filho et al. 17490 ( UEC) , 07 July 1995, Rivadavia et al. 454 ( SPF) ; Estrada para Conselheiro Mata , 18 July 1980, Menezes et al. CFCR 135 ( NY, R, SPF), 18 December 1985, Simão et al. CFCR 8782 ( SPF) , 10 January 1987, Grandi et al. 2324 ( BHCB) , 18 July 1987, Mello-Silva & Pirani CFCR 11057 (R, SP, SPF) , 28 February 1997, Rivadavia & Pinheiro 586 ( SPF) , 10 December 1997, Forzza et al. 564 ( SPF) , 29 June 2003, Rivadavia 1632 ( SPF) , 05 September 2011, Gonella et al. 464 ( SPF) ; Estrada Diamantina–Mendanha , 27 January 1969, Irwin et al. 22697 ( NY, UB) , 10 August 2010, Gonella et al. 349 ( SPF) ; Estrada para Milho Verde , 10 April 1982, Menezes et al. CFCR 3279 ( SPF) ; Morro dos Cruzeiros , August 1945, Vidal s.n. (R) ; próximo à Cach. da Toca , 25 February 1992, Rivadavia 77 ( SPF) ; próximo a condomínio ao Sul da cidade, 20 April 2010, Gonella et al. 271 ( SPF) ; Serra ao NW da cidade, 27 February 1997, Rivadavia & Pinheiro 578 ( SPF) ; Serra do Espinhaço , 08 September 1971, Hatschbach 27487 ( MBM) , 16 August 1972, Hatschbach 30198 ( BHCB, MBM) ; Município de Grão Mogol, descida do Morro do Papo da Ema para Jambeiro , 09 March 1990, Pirani et al. CFCR 13096 ( NY, RB, SPF) ; em direção nordeste da cidade, 22 May 1982, Mamede CFCR 3471 ( MBM, NY, R, SPF) ; Jambeiro a 7 km de Grão Mogol, 05 September 1985, Cavalcanti et al. CFCR 8526 ( BHCB, F, MBM, NY, R, SP, SPF) ; Serra de Grão Mogol , 12 November 1938, Markgraf et al. 3433 ( BHCB) ; subida para o Morro Papo da Ema , 06 September 1990, Silva et al. CFCR 13427 (F, K, MBM, NY, RB, SPF) ; trilha da Tropa, 02 June 1994, Rivadavia 264 ( SPF) , 07 September 1994, Rivadavia 295 ( SPF) ; trilha saindo de Grão Mogol em direção oeste, 09 September 1994, Rivadavia 303 ( SPF) ; Vale do Rio das Mortes , 24 July 1986, Zappi et al. CFCR 9940 (K, NY, R, RB, SPF, SP) . Município de Itacambira, estrada para Itacambira , 16 December 1994, Rivadavia 308 ( SPF) ; estrada para Montes Claros , 05 March 1997, Rivadavia 605 ( SPF) , 13 October 2001, Rivadavia 1282 ( SPF) ; estrada Montes Claros–Itacambira (MG-308), 22 April 2010, Gonella et al. 286 ( SPF) , 12 February 2011, Gonella et al. 393 ( SPF) ; Serra Resplandecente , 31 August 2003, Vasconcelos 95 ( BHCB) ; sul de Itacambira, 17 December 1994, Rivadavia 318 ( SPF) . Município de São Gonçalo do Rio Preto, Parque Estadual do Rio Preto , 10 May 2004, Viana et al. 1763 ( BHCB) ; Chapada do Couto , 12 July 2007, Mota 842 ( BHCB) ; entre cachoeiras do Crioulo e Deitada , 28 June 2003, Rivadavia & Deco 1607 ( SPF) ; entre as cachoeiras Deitada e Sempre-Viva , 28 June 2003, Rivadavia & Deco 1619, 1623 ( SPF) ; trilha para o alto da chapada, 05 February 2009, Gonella & Viana 190 ( SPF) ; trilha para o morro Redondo , 06 February 2009, Gonella & Viana 204 ( SPF) . Município de Serro, Milho Verde , extremo norte da planície ao lado da cidade, 05 April 2003, Rivadavia & Neves 1568, 1569 ( SPF) ; à esquerda da estrada de Milho Verde para Diamantina , 06 April 2003, Rivadavia 1583 ( SPF) ; estrada de Milho Verde para Capivari , 13 May 2007, Rivadavia 2556 ( SPF) . Município de Rio Vermelho, Platô Pedra Menina , 09 September 1986, Cordeiro et al. CFCR 10249 ( BHCB, F, MBM, R, RB, SP, SPF) ; Serra da Torre , 11 July 1999, Rivadavia et al. 1107 ( SPF) . Without location data, no date: Gardner 4417 ( NY photo!) .

Figures

FIGURE 1. Distribution of D. graminifolia (square) and D. spiralis (circles).

FIGURE 4. Drosera spiralis (B based on Gonella et al. 286 from Itacambira, Minas Gerais; all others based on Gonella et al. 464 from Diamantina, Minas Gerais). A, habit. B, stipule. C, petiole, abaxial surface. D, petiole, adaxial surface. E, apex of the leaf, abaxial surface. F, detail of the scape indumentum. G, side view of the calyx. H, seed. Drawn by P. M. Gonella.

FIGURE 5. Drosera spiralis. A, growing in a boggy seepage habitat at Itacambira, Minas Gerais. B, habit, at Itacambira, MG. C, growing in cracks of quartzitic sandstone at Botumirim, Minas Gerais. D, flower. E, tentacle-like emergences on the sepals. F, young leaf showing the irregular circinate vernation. G, base of the rosette showing the long stipules and short petioles (all by P.M. Gonella).