Drosera schwackei ( Diels 1906: 89 ) Rivadavia (2008: 39)

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 : 56-57

25. Drosera schwackei ( Diels 1906: 89) Rivadavia (2008: 39) . Figures 6c, 20c–f

≡ Drosera montana var. schwackei Diels (1906: 89) .

Lectotype (designated by Silva & Giulietti 1997):— BRAZIL. Minas Gerais: Serra do Cipó, 1892, Schwacke 8234 (OUPR-11278!; isolectotype RB-116702! pro-parte, mixed with Schwacke 8235).

Perennial, rosetted, acaulescent or often forming very short stocky stems densely covered by marcescent leaves. Glandular trichomes of TSG type present on both leaf surfaces, scapes, pedicels and sepals; dense eglandular indumentum present on the abaxial leaf surface, adaxial petiole surface, scape (from base to apex), pedicels and sepals. Leaves elliptic to oblong-lanceolate, semi-erect, yellow-green to orange-green; petioles much shorter than the lamina (petiole:lamina ratio of ca. 1/2); stipules rectangular, translucent-white, 2.2–2.5(–3.0) × 1–2 mm, apical half to third fimbriate. Scape with erect base; petals pink; gynoecium 3-carpelate, styles bifurcated at the base. Seeds narrowly oblong, 0.7–0.8 mm long, with reticulate testa.

Illustrations: — Rivadavia (2008: 40, fig. 3—habit and details).

Distribution: — Brazil (Southeast: MG), endemic. Restricted to the northern Serra do Cipó (Congonhas do Norte and Santana do Pirapama) and the Diamantina Plateau in the Espinhaço Range of Minas Gerais (Fig. 6c).

Habitat: —Relatively dry areas of campo rupestre vegetation, in fine silica sand mixed with white quartz gravel at elevations between 1200–1370 m.

Phenology:— Found with flowers from February to April (mid to late wet season), sometimes with a few individuals continuing to flower into the dry season in July.

Conservation status: —Endangered (EN) B1ab(iii, iv)+2ab(iii, iv). Drosera schwackei presents a restricted occurrence (EOO= 1,015 km 2, AOO= 24 km 2), where it usually forms small sparse populations in a very specific habitat. The area that harbors the largest number of known sub-populations has been a focus of urban expansion for the town of Diamantina over the past decade and may be completely developed by human settlements in the very near future. This urban expansion further facilitates invasion by exotic grasses, which outcompete native flora. Furthermore, similarly to all campos rupestres species, D. schwackei is threatened by dramatic reduction in habitat suitability from climate change. This taxon is here considered EN based on the very restricted EOO and AOO, as well as an observed and projected continued decline of both habitat area and quality. The only conservation area it is known to grow in is the Biribiri State Park.

Notes: — Drosera schwackei is distinguished from all other Brazilian species possessing TSG trichomes by having short, translucent-white rectangular stipules (vs. large, translucent-golden-brown triangular stipules in all other species possessing TSG trichomes). It is also comparatively much smaller than the majority of other species with this indumentum character, being most similar to D. quartzicola in this regard. However, D. schwackei is distinguished from D. quartzicola by the elliptic to oblong-lanceolate leaves with petioles much shorter than the lamina (vs. lanceolate leaves with petioles as long as the lamina), the adaxial petiole surface densely eglandular-pilose (vs. eglandular trichomes absent), and the longer inflorescences 60–180 cm long (vs. 17–115 mm long).

Two geographical morphotypes can be recognized in D. schwackei , representing variations in leaf shape. No other differences could be observed in the reproductive organs of the studied specimens.

i. “Type morphotype”: represented by the designated lectotype (Schwacke 8234), this morphotype presents more compact rosettes of shorter leaves with elliptic lamina (Fig. 20d), often showing a darker orange-red coloration. It can be found in the southern range of the species’ distribution, on the southern end of the Diamantina plateau (where it is represented by populations along the road to Conselheiro Mata district) and on the northern end of the Serra do Cipó.

ii. “Diamantina morphotype”: represented by the specimen Sckwacke 3235 and other collections, is restricted to a narrow range in the vicinity of the town of Diamantina. This morphotype is found in the northern end of the species’ distribution. It presents longer leaves, which are oblong-lanceolate in shape (Fig. 20c), often showing a greener coloration.

Specimens examined: —For an extensive listing, see Rivadavia (2009).

Additional specimens examined: — BRAZIL. Minas Gerais: Congonhas do Norte, Serra Talhada , 23 June 2013, Gonella et al. 630 ( SPF) . Diamantina, estrada que sai do Bairro Arraiola , 24 July 2008, Gonella et al. 163 ( SPF) ; ibid., 25 July 2008, Gonella et al. 175 ( SPF) ; ibid., 08 February 2009, Gonella & Viana 217 ( SPF) ; estrada vicinal em frente ao clube de campo do Banco do Brasil , 13 April 2011, Mello-Silva et al. 3407 ( SPF) ; sul da cidade, estrada das Bicas, 09 March 2013, Gonella 617 ( SPF) ; Estrada para Conselheiro Mata , 05 March 2018, Gonella et al. 927 ( DIAM) ; ibid., 05 March 2018, Gonella et al. 928 ( DIAM) . Diamantina, Biribiri , 06 April 1892, Schwacke 8235 [B-100272054!; RB-116702! pro -parte (single scape)—original material]; Parque Estadual do Biribiri , 30 March 2018, Gonella 936 ( DIAM) . Serra do Cipó , 23 April 1892, Glaziou 18858 (K-001204936!, P-749162!—original material) .