Drosera spiralis Saint-Hilaire (1826: 270)

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 : 59-60

27. Drosera spiralis Saint-Hilaire (1826: 270) . Figures 6d, 21a–c

Type: — BRAZIL. Minas Gerais: Serra de Curumatahy, District des Diamans aux bords du Corgo novo [Serra de Curimataí (current municipality of Buenópolis), Diamantina district, on the margin of Corgo Novo river], s.d. [September according to protologue], Saint-Hilaire B 1-2021bis (holotype P-00749155!) .

= Drosera brasiliensis Martius ex Eichler (1872: 396) nom. inval.

Perennial, rosetted, acaulescent or forming short upright to prostrate stocky columns up to 10 cm long. Stalked glandular trichomes 0.1–0.5 mm long present on leaves, scapes, pedicels and calyx. Leaves erect, with irregular circinate vernation, linear, densely glandular- and eglandular-pilose abaxially, petioles short, 5–30 mm long, often hidden by the large stipules; stipules triangular, 14–22(–30) × 8–22 mm, golden-brown in color. Scapes erect at the base, densely glandular- and eglandular-pilose throughout; sepals densely glandular- and eglandular-pilose, often bearing 1–several tentacles; petals pink; gynoecium 3-carpelate, styles bifurcated at the base. Seeds ovoid, 0.60–0.65 × 0.25–0.30 mm, black, with reticulate testa.

Illustrations: —Eichler (1872: t. 91, fig. II—two habit drawings and details—as D. graminifolia ); Diels (1906: 87, figs. 31M, N—stipule and seed—as D. graminifolia ); Silva & Giulietti (1997: 86, fig. 6—as D. graminifolia ); Gonella et al. (2012: 50, fig. 4—habit and details).

Distribution: — Brazil (Southeast: MG), endemic. Restricted to the central and northern Espinhaço Range in Minas Gerais, on the Diamantina Plateau and the highlands between Itacambira and Grão Mogol (Fig. 6d).

Habitat: —Grassy seepages and occasionally along river margins, in humid to wet sandy soils, as well as in cracks of sandstone, in campos rupestres vegetation, between 700–1500 m a.s.l.

Phenology: —Flowering mainly between April and December, with sparse individuals found in flower yearround.

Conservation status: —Vulnerable (VU) B1ab(iii). Drosera spiralis was considered LC by Gonella et al. (2012). However, based on new evidence of the calculated extent of occurrence (EOO= 10,534 km 2) and area of occupancy (AOO= 252 km 2), the designation VU is applied based on increased loss due to agriculture, cattle ranching, quartzite mining, eucalypt plantation, and urban expansion, as well as the frequent occurrence of anthropogenic fires along the whole range of the species, reducing the quality of habitats and facilitating growth of invasive exotic grasses. It is further threatened by reduction of habitat suitability in the next decades by climate change. Populations of the species are recorded from the Sempre-Vivas National Park as well as the Biribiri, Botumirim, Rio Preto, and Grão-Mogol State Parks.

Notes: — Drosera spiralis is most similar to D. graminifolia with which it shares linear leaves, but is distinguished by general indumentum type and morphology, stipule and petiole size, leaf vernation pattern, as well as seed shape and size, as discussed under that species and in Gonella et al. (2012).

The species was placed under synonymy of D. graminifolia by Diels (1906), a concept that was adopted by all subsequent works until Gonella et al. (2012), which re-established Saint-Hilaire’s (1826) two-species concept based on the significant morphological and ecological differences between the taxa.

The name D. brasiliensis Martius ex Eichler (1872: 396) was published by Eichler (1872) based on notes by Martius. However, Eichler lists it as a synonym of D. graminifolia , rendering it an invalid name (ICN Art. 36.1; Turland et al. 2018). The taxon is conspecific with D. spiralis ( Gonella et al. 2012, 2015).

Specimens examined: —For a complete list, see Gonella et al. (2012: 53–54).

Additional specimens examined: — BRAZIL. Minas Gerais: no date, Gardner 4417 (W—3 sheets).