Cuphea gracilis Kunth (1824: 199)

Facco, Marlon Garlet & Cavalcanti, Taciana Barbosa, 2023, Taxonomic Revision of Cuphea sect. Trispermum s. l. (Lythraceae), Phytotaxa 588 (1), pp. 1921-1935 : 1921-1935

11. Cuphea gracilis Kunth (1824: 199) .

Cuphea gracilis var. orinocensis Saint-Hilaire (1833: 100) . Cuphea gracilis var. media Koehne (1877: 284) .

Lectotype (designated by Lourteig 1987: 25 ):— VENEZUELA. [Amazonas]: “crescit prope Atures, locis arenosis ( Orinoco [river]) [approx. 5.612, -67.614]”, May 1800, Humboldt & Bonpland 857 ( P [00679419] image!, isolectotypes B image!, K [fragm.] image!) . Figs. 11A–F , 18 .

Cuphea multicaulis Koehne (1877: 228) . Lectotype (first step designated by Lourteig 1987: 25, second step lectotypification here designated):—[ COLOMBIA]. [Vichada]: “ad cataractas Maypures [approx. 5.243, -67.852]”, June 1854, Spruce 3727 (P [01901646] image!, isolectotypes BM, F [fragm.] image!, K image!, P [01901647] image!).

Cuphea pauciflora Koehne (1903: 132) . Lectotype (here designated):— VENEZUELA. “Cuchivero, am Fusse der grossen Stromschnellen”, Selwyn auf der Exp. Passarge n. 809 ([illustration] “ C. pauciflora ” in Koehne, Atlas Lythracearum, ined., Gray Herbarium: pl. 75. 1902).

Subshrubs 30–50 cm tall; stems erect to decumbent, indumentum strigose and pubescent, one-armed trichomes, and short eglandular trichomes, <0.5 mm long, with curved apices, sometimes concentrated in a longitudinal band along the stem; internodes 0.7–3 cm long; brachyblasts absent. Leaves opposite, membranaceous, petioles ca. 1 mm long, blades 8–30 × 2.5–5 mm, narrow-ovate, apex acute, base acute to obtuse, margin plane to subrevolute, indumentum strigose on both surfaces; hyphodromous, secondary veins rarely visible. Racemes 10–22 cm long, bracteose, simple to compound, elongated, distinct; bracts 3–13 × 1–3 mm, subequal pairs, similar to leaves in shape and indumentum. Flowers alternate; pedicels 2–5 mm long; bracteoles 0.6–0.7 mm long, ovate; floral tubes 6–7 mm long; spur obtuse, deflexed; outer surface purple, indumentum pubescent, mixed with sparse glandular trichomes; inner surface villous behind the stamens, pilose on the rest of the floral tube; petals 6, purple to magenta, subequal, two dorsal 3–3.2 × 1.2– 1.7 mm, obovate, four ventral 2.7–3.4 × 1.2–1.6 mm, obovate; stamens free in the upper third of the floral tube, five antesepalous exserted, four antepetalous subexserted; pistil ca. 3.2 mm long; ovary glabrous; style pilose to glabrous; ovules 3; nectary ca. 0.6 × 0.7, deflexed. Seeds 2–3, 2 × 1.7–1.9 mm, elliptic to obovate, apex retuse, base acute to obtuse, margin obtuse.

Phenology: —Collected with flowers and fruits in May, June, July, and September.

Distribution and habitat: — Colombia, in department of Vichada, and Venezuela, in Amazonas state ( Fig. 18 ) ( Lourteig 1987 , 2007); granite outcrops on riverbanks, and Amazonian savannas; 60–80 m elev.

Conservation status: — Cuphea gracilis was categorized as Endangered (EN) B1ab(i,ii,iii)+2ab(i,ii,iii), with an estimated EOO of 500 km ² and AOO of 24 km ². It is a narrowly endemic species, whose populations are threatened by massive hydroelectric projects in the rivers where the species is found ( Funk et al. 2007).

Specimens examined: —COLOMBIA. Vichada: [Cumaribo], Maipures, plantes des bords de l’Orénoque, Chaffanjon 514 (P image!). VENEZUELA. Amazonas: savane d’Atures, plantes des bords de l’Orénoque, 12 June 1887, Gaillard 23 (P!); [Atures], Puerto Ayacucho, great rapids of the Orinoco, cristalline laja, 1–1.5 km east of Hotel Amazonas, 07 September 1953, Maguire et al. 36053 (P image!); Atures, carretera Puerto Ayacucho-Sanariapo [Samariapo] desde Pto. Ayacucho hasta el Km 35 hacia Sanariapo [Samariapo], en sabana llanera con bosques ocasionales, cerca de la carretera, 6–19 July 1969, Bunting et al. 3500 (P image!); [Atures], Puerto Ayacucho, between the electric power plant and the Rio Orinoco, 05º40’00”N, 67º37’00”W, 23 June 1984, Davidse & Miller 26439 (P!); Atures, Parque Sucre, on rocky igneous savanna slope just south of Puerto Ayacucho, 05º43’00”N, 67º37’00”W, 08 September 1985, Steyermark et al. 131594 (P!); Atures, Rio Sipapo, 5 km de su desembocadura al Rio Orinoco, Cerro Caldero, 05º01’00”N, 67º46’00”W, 17 May 1992, Groger & Barcroft 408 (P image!).

Cuphea gracilis is characterized by narrow-ovate leaves ( Fig. 11B ) and long, distinct bracteose racemes ( Fig. 11A ). It occurs in the border between Venezuela and Colombia, in the granite outcrops on the banks of the Orinoco river and its tributary, the Sipapo river, and in adjacent savanna regions. Cuphea gracilis is morphologically close to C. carajasensis , but can be distinguished by the glabrous ovary, with the villous indumentum present only on the inner surface behind the stamens. In C. carajasensis , the dorsal region of the ovary is densely villous, and is restricted to habitats with ironstone outcrops in the state of Pará, Brazil ( Cavalcanti et al. 2016).

There are five varieties related to C. gracilis , two described by Saint Hilaire (1833) ( C. gracilis var. brasiliensis Saint-Hilaire [1833: 100] and C. gracilis var. orinocensis ) and three by Koehne (1877) ( C. gracilis var. major Koehne [1877: 284], C. gracilis var. media and C. gracilis var. minor Koehne [1877: 284]). The typification and identity of these varieties are discussed below.

In “ Flora Brasiliae Meridionalis ”,Saint Hilaire(1833) made a brief comment contrasting C.gracilis var. orinocensis from C. gracilis var. brasiliensis . There is the remark “ (Humboldtiana) ” right after the name “ Orinocensi ”. The author probably created this variety based on the type of C. gracilis , collected by F.W. von Humboldt and A.J.A. Bonpland. Cuphea gracilis var. brasiliensis was removed from this study because its identification is close to C. retrorsicapilla Koehne (1877: 279), from C. sect. Euandra subsect. Oidemation Koehne (1883: 395, 399) (see discussion in Graham & Cavalcanti 2013).

Cuphea gracilis var. media has also been described based on the collection of F.W. von Humboldt & A.J.A. Bonpland, among other specimens ( Koehne 1877 ). However, Lourteig (1987) made a mistake in lectotypifying this variety under “ Spruce 3728 ”, since this material is cited by Koehne (1877) for C. gracilis var. minor together with “ Karsten s.n.”. Furthermore, the latter two collections are correctly identified as C. odonellii , thus C. gracilis var. minor was synonymized here under this species.

Cuphea gracilis var. major was considered as a synonym of C. antisyphilitica var. acutifolia by Lourteig (1987) , who cited a specimen “ Riedel 920 ” in P as “ holotype ”. After analyzing the image of the specimen, it was concluded that its morphology is similar to that of members of C. sect. Euandra subsect. Oidemation , however, its identity has not yet been determined.

Koehne (1903) placed C. pauciflora in C. sect. Euandra subsect. Hilariella Koehne (1881: 156), because of the length of the stamens and the habit, since he did not see the seeds (the shape of the seed margin is important for infrageneric classification). Lourteig (1987) considered C. pauciflora as a synonym of C. gracilis and commented that she only saw the illustration in Koehne’s unpublished Atlas (“ Atlas Lythracearum ”). In the protologue and illustration there are several striking characters of C. sect. Trispermum s.l., and of C. gracilis , such as delicate branches, long, bracteose racemes, 3 ovules, and vesicles absent. In addition, the collection locality of the type material is close to the occurrence area of C. gracilis . Finally, the species was kept here as a synonym of C. gracilis . In this revision, no specimen related to C. pauciflora was found in the herbaria examined. The species was then lectotypified here with the illustration of the original type material from Koehne’s unpublished Atlas , which includes details of the branches, floral tube in lateral view and in longitudinal-dorsal section, pistil, and nectary.

Figures

FIGURE 11. A–F. Cuphea gracilis. A. Habit; B. Detail of branches; C. Floral tube in lateral view, without petals; D. Floral tube in longitudinal-dorsal section, without petals; E. Pistil; F. Seed. G–M. Cuphea inaequalifolia. G. Habit; H. Inflorescence branch; I. Flower in lateral view; J. Floral tube in lateral view, without petals; K. Floral tube in longitudinal-dorsal section, without petals; L. Pistil; M. Seed. A, B, E: Steyermark et al. 131594; C, D, F: Davidse & Miller 26439; G, I: Pereira-Silva et al. 17024; H, J–M: Pereira-Silva et al. 17088. Scale bar.A: 5 cm; C, D, L: 2 mm; E, F, M: 1 mm; J–K: 3 mm.

FIGURE 18. Geographical distribution of Cuphea anisoclada, Cuphea congesta, Cuphea gracilis and Cuphea rionegrensis.