Cuphea carajasensis Lourteig 1987

6. Cuphea carajasensis Lourteig (1987: 13).

Type:— BRAZIL. Pará: Marabá, Serra dos Carajás, N-4 [approx. -6.051, -50.174], mina piloto para exploraç ã o de ferro, alt. 700 a 750 m, 14 March 1984, Silva, Rosa, Bahia & Santos 1778 (holotype P [01901532] image!, isotypes INPA!, MG!, NY image!, R). Figs. 8I–O, 19.

Subshrubs 30–100 cm tall; stems erect, indumentum glabrescent to pubescent, eglandular trichomes <0.5 mm long, erect or with curved apices, rare glandular trichomes or one-armed appressed trichomes, sometimes the indumentum is distributed in a longitudinal band along the stem; internodes 0.5–3 cm long; brachyblasts absent. Leaves opposite, chartaceous, sessile to subsessile, blades 5–35 × 0.5–8 mm, linear, narrow-ovate to ovate, apex acute, base acute to obtuse, rarely cordate, margin plane to subrevolute, surfaces glabrous or with sparse one-armed appressed trichomes; hyphodromous, secondary veins rarely visible. Racemes 5–15 cm long, bracteose, rarely frondose-bracteose, simple to compound, elongated, distinct; bracts 2–20 × 0.5–3 mm, subequal pairs, usually linear, similar to leaves in indumentum. Flowers alternate; pedicels 1.3–3.4 mm long; bracteoles 0.5–0.8 mm long, ovate; floral tubes 6–9 mm long; spur obtuse, horizontal to deflexed; outer surface vinaceous to purple, indumentum pubescent, mixed with short glandular trichomes, <0.5 mm long; inner surface villous on almost the entire floral tube, rarely only pilose in the lower third; petals 6, lilac to purple, rarely carmine, subequal, two dorsal 3.2–5 × 1.6–2.7 mm, obovate, four ventral 3–5.4 × 1.3–2.7 mm, narrow-obovate to obovate; stamens free in the upper third of the floral tube, five antesepalous exserted, four antepetalous subexserted; pistil 4–6 mm long; ovary densely villous in the dorsal region; style villous in the basal portion; ovules 2–3; nectary ca. 0.8 × 0.5 mm, horizontal to slightly deflexed. Seeds 1–2, 1.9–2.3 × 1.8–2.1 mm, broadelliptic to suborbicular, apex obtuse, truncate to slightly retuse, base obtuse, margin slightly thickened.

Phenology: —Collected with flowers and fruits from October to May, with highest fruit production from December to March.

Distribution and habitat: — Brazil, in Pará state (Fig. 19); ecosystems with ironstone outcrops (“cangas”), such as swamps and grasslands, and edges of dense ombrophilous forests; 633–800 m elev.

Conservation status: — Cuphea carajasensis was categorized as Endangered (EN) B1ab(i,ii,iii)+2ab(i,ii,iii), with EOO of 3,258 km ² and AOO of 88 km ². It is a narrow endemic species of Serra dos Carajás and Serra Arqueada, a region that suffers from intense exploration for iron ore, among other minerals, since this location stands out as one of the largest mineral provinces in the world (Freitas 1986, Santos 1986). Despite the existence of the conservation unit “Floresta Nacional de Carajás” (ICMBio 2016), the populations of C. carajasensis are threatened by growing exactly on the iron outcrops drained by mining companies. Furthermore, a unique population of carmine flowers from Serra Arqueada is totally unprotected, outside this conservation unit.

Representative specimens examined: —BRAZIL. Pará: Cana ã dos Carajás, Serra Sul, 06°23’49”S, 50°20’57”W, 06 December 2007, Viana et al. 3349 (BHCB!, RB!); Cana ã dos Carajás, Floresta Nacional dos Carajás, Serra Sul, Corpos A, B, C e Brejo, 06°22’48”S, 50°22’55”W, 08 December 2007, Mota et al. 1106 (BHCB!, MG!, RB!); Cana ã dos Carajás, Serra do Tarzan, 06°20’02”S, 50°09’25”W, 13 March 2009, Giorno et al. 126 (BHCB!); Cana ã dos Carajás, Serra da Bocaína, 06°18’35”S, 49°54’03”W, 28 January 2013, Arruda et al. 1396 (BHCB!); Cana ã dos Carajás, FLONA de Carajás-Serra dos Carajás, S11 D, 30 March 2015, Cardoso et al. 2013 (RB!); Cana ã dos Carajás, Serra dos Carajás, Serra Sul, S11 C, 06°23’06”S, 50°23’03”W, 23 March 2016, Harley et al. 57432 (RB!); Marabá, Serra dos Carajás, Serra do Norte, Clareira N1, 18 April 1970, Cavalcante & Silva 2639 (MG!, NY image!); Marabá, Serra dos Carajás, N4, 25 March 1977, Silva & Bahia 2923 (MG!, P image!); Ourilândia [do Norte], Serra Arqueada, 06º30’33”S, 51º09’23”W, 03 May 2016, Viana et al. 6183 (CEN!, MG!); Parauapebas, Acampamento AMZA, N1, aeroporto, 06°01’00”S, 50°18’00”W, 18 May 1982, Sperling et al. 5728 (K image!, MG!); Parauapebas, Serra do Rabo, Norte, 06°18’14”S, 49°53’37”W, 15 December 2010, Mota et al. 1890 (BHCB!, IAN!); Parauapebas, Serra de Carajás, Núcleo Urbano de Carajás, mina N1, ca 8 km da estrada do Manganês, 06º02’11”S, 50º17’01”W, 10 February 2011, Lima & Silva 7108 (RB!); Parauapebas, FLONA de Carajás, Serra Norte, N1, 06°02’30”S, 50°16’14”W, 26 March 2015, Viana et al. 5568 (CEN!).

Cuphea carajasensis is characterized by sessile, narrow-ovate (Fig. 8K) to linear leaves, long and distinct bracteose racemes (Fig. 8I, J), and by the villous ovary in the dorsal region (Fig. 8N), which is uncommon in the genus. Cuphea carajasensis is directly associated with the plateaus of isolated outcrops of ironstone (“cangas”) in Serra dos Carajás, a mountainous complex embedded in the Amazonian phytogeographic domain in the southeastern state of Pará, Brazil (Cavalcanti et al. 2016, Viana et al. 2016). Recently, a population with carmine flowers (Fig. 8J) was discovered in Serra Arqueada (southwestern Carajás) that contrasts with the typical lilac to purple flowers (Fig. 8I), however, according to molecular data (Cavalcanti, pers. comm.), it is only a phenotypic variation of the species.

Among the species of C. sect. Trispermum s.l., C. gracilis and C. praetermissa are morphologically similar to C. carajasensis. However, in these two species the inner surface of the floral tube is villous only behind the stamens, and the ovary is glabrous, rarely pilose. And in C. praetermissa the leaves are 3–4(–5)-verticillate at midstem, with strongly revolute margin to the midvein. The geographical distribution is also distinct: C. gracilis occurs between Venezuela and Colombia, and C. praetermissa in the “cerrados” of the states of Tocantins and Maranh ã o, Brazil.

Lourteig (1987) placed C. carajasensis in C. sect. Euandra subsect. Platypterus Koehne (1881: 147) due to the presence of a horizontal nectary and seeds with a “slight border”, characters uncommon to the typical definition of C. sect. Trispermum. Analysis of pollen grains of this species revealed that the exine is thickened in the region between the pores (Facco et al. 2021), a strong synapomorphy of the section (Graham et al. 2006). In ongoing molecular analyses, C. carajasensis appeared in the “ Trispermum clade” (Cavalcanti, pers. comm.). Based on this morphological and molecular evidence, C. carajasensis was transferred here to C. sect. Trispermum s.l.