Cuphea tenuissima Koehne (1877: 254)

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

20. Cuphea tenuissima Koehne (1877: 254) .

Lectotype (here designated):— BRAZIL. [Tocantins]: “Porto Real [in the protologue: Porto Imperial; currently Porto Nacional, -10.716, -48.416]”, [1829], Burchell 8533-2 ( K [000532969] image!, isolectotypes BR, GH p.p. image!, K p.p. [000532970] image!, L image!, NY image!, OXF image!, P image!, US image!). Figs. 16 , 20 .

Subshrubs 10–60 cm tall; stems erect, indumentum strigose and hirsute, or just strigose, one-armed trichomes, and long glandular trichomes, 1–2 mm long, mixed with sparse short eglandular trichomes, <0.5 mm long, erect or with curved apices; internodes 0.5–4 cm long; brachyblasts absent. Leaves opposite, rarely subalternate, chartaceous, sessile to petiolate, petioles ca. 1 mm long, blades 10–50 × 1–2(–4) mm, linear, rarely narrow-ovate, apex acute, base obtuse, margin strongly revolute to the midvein, indumentum strigose on both surfaces, sometimes glandular trichomes present; hyphodromous, main vein prominent on abaxial surface. Racemes 5–20 cm long, bracteose, rarely frondose-bracteose, simple to compound, elongated, distinct; bracts 1.5–50 × 0.5–2 mm, subequal pairs, narrow-ovate to linear, similar to leaves in indumentum. Flowers alternate to fasciculate, pedicels 1–5 mm long; bracteoles 0.4–0.5 mm long, ovate; floral tubes (4–) 5–6.7 mm long; spur obtuse, slightly horizontal to deflexed; outer surface vinaceous to purple on the dorsal region, green ventrally, indumentum slightly strigose, glandular trichomes on the veins; inner surface villous behind the stamens, slightly pilose around the ovary, rarely glabrous; petals 6, pink to purple, subequal, two dorsal 2.5–4.5 × 0.7–1.3 mm, narrow-obovate to narrow-elliptic, four ventral 2.5–4.4 × 0.7–1.2 mm, narrowobovate to narrow-elliptic; stamens free in the middle third of the floral tube, fully included; pistil 2–3.5 mm long; ovary glabrous, rarely pilose in apical portion; style glabrous; ovules 3; nectary 0.3–0.5 × 0.4–0.5 mm, deflexed. Seeds 2–3, 1.5–2.2 × 1.2–1.8 mm, elliptic, obovate to suborbicular, apex obtuse to slightly retuse, base acute to obtuse, margin obtuse.

Phenology: —Collected with flowers and fruits from December to April.

Distribution and habitat: — Brazil, in the states of Goiás, Maranh ã o, Mato Grosso, Minas Gerais, Pará, and Tocantins ( Fig. 20 ); wet grasslands, “veredas”, “cerrado ralo”, “cerrado rupestre”, and sometimes in pastures; 200– 1000 m elev.

Conservation status: — Cuphea tenuissima was categorized as Least Concern (LC) due to its wide geographic distribution.

Representative specimens examined: —BRAZIL. Goiás: Alto Horizonte, Fazenda do Senhor Jair Eustáquio, 26 February 2011, Faria-Junior 1165 (CEN!, UB!); Cavalcante, balsa Serra Branca (Rio Tocantins), Serra Branca, km 5, 13º23’43”S, 48º08’07”W, 23 January 2001, Pereira-Silva et al. 4569 (CEN!); Minaçu, balsa do Rub ã o, km 12, marca do rio Bonito na rua 20, 13º36’55”S, 48º11’20”W, 19 February 2002, Pereira-Silva et al. 5828 (CEN!). Maranhão: Balsas, Projeto de balsas, condomínio Kissy, lote 23, 09 March 1996, Pereira-Silva et al. 3476 (CEN!); Carolina, P.N. Chapada das Mesas, acesso E no Km 612 da BR-230, 20 km em estrada vicinal em direç ã o à localidade Buenos Aires, 06º55’53”S, 47º22’40”W, 06 April 2016, Simon et al. 2699 (CEN!); Estreito, canteiro de obras do UHE Estreito, limite leste, junto a rodovia, 06º35’29”S, 47º26’18”W, 12 March 2007, Pereira-Silva & Moreira 11393 (CEN!); Estreito, margem direita do rio Feio, 06°45’24”S, 47°28’09”W, 19 January 2010, Pereira-Silva & Moreira 14958 (CEN!). Mato Grosso: Santa Cruz do Xingu, Parque Estadual do Xingu, limite norte do Parque, 09º41’25”S, 52º36’33”W, 03 March 2011, Zappi et al. 3081 (CEN!); Santa Cruz do Xingu, Fazenda Najá, zona de amortecimento do Parque Estadual do Xingu, 09°44’29”S, 52°17’45”W, 11 March 2011, Silva et al. 28 (CEN!); S ã o Félix do Araguaia, estrada entre a Vila de Pontinópolis e a Serra dos Magalh ã es, 11º33’39”S, 51º13’00”W, 21 March 1997, Souza et al. 14766 (CEN!, ESA!). Minas Gerais: Formoso, rodovia Goiás Minas-Formoso, km 14, 15º04’28”S, 46º23’60”W, 20 April 1997, Cavalcanti et al. 2260 (CEN!); Paracatu, BR-040, Paracatu-Jo ã o Pinheiro, Km 4, 21 April 1997, Cavalcanti et al. 2263 (CEN!). Pará: Conceiç ã o do Araguaia, Redenç ã o, area of cerrado-vegetation about 4 km west of town center along highway PA-150, 08º02’00”S, 50º04’00”W, 21 February 1980, Plowman et al. 8981 (HRB!, INPA!, P image!); Cumaru do Norte, Reserva Florestal de Gorotire (Kayapó-indian Reservation), surroundings of Gorotire village at Rio Fresco, 51º07’00”W, 07º47’00”S, 13 January 1983, Gottsberger & Posey 14-13183 (MG!, P image!). Tocantins: Araguaína, margem da Belém-Brasília, 30 km ao norte de Araguaína, 07°03’05”S, 48°06’42”W, 05 February 1999, Lima et al. 66 (CEN!); Barra do Ouro, Balsa Bom Tempo (Rio Manoel Alves Grande)-Barra do Ouro, km 28, 07º40’03”S, 47º35’20”W, 19 January 2008, Pereira-Silva & Moreira 12786 (CEN!); Itacajá, Reserva Indígena Krahò, 05 March 1999, Pereira-Silva et al. 4080 (CEN!); Lagoa da Confus ã o, Ilha do Bananal, sede do Parque Nacional do Araguaia, ca. de 600 m da sede em direç ã o a aldeia Carajá Macaúba, 10º27’48”S, 50º28’52”W, 19 March 1999, Aparecida-daSilva et al. 3986 (CEN!); “Porto Real” [Porto Nacional], [1829], Burchell 8487 (BR image!, GH p.p. image!, K p.p. image, L image!).

Cuphea tenuissima is characterized by linear leaves ( Fig. 16A ), 1–2(–4) mm wide, with strongly revolute margins reaching the midvein ( Fig. 16B ), small, slender floral tubes, (4–) 5–6.7 mm long, arranged in long bracteose racemes, and by fully included stamens, free in the middle third of the floral tube ( Fig. 16E ). The species is endemic to the central region of Brazil, in savanna and grassland formations of the Cerrado biome. Cuphea tenuissima is morphologically similar to C. praetermissa , which is characterized by 3–4(–5)-verticillate leaves at midstem, distally opposite, larger and thicker floral tubes, (6–) 7–8 mm long, and by stamens with filaments free in the upper third of the floral tube, exserted. Phylogenetic analyses based on AFLP and ITS data (Facco, unpublished data) confirmed C. praetermissa as a separate species from C. tenuissima .

Previously included in C. sect. Brachyandra subsect. Micranthium , together with C. micrantha ( Koehne 1903) , C. tenuissima was transferred to C. sect. Trispermum s.l. after palynological ( Graham & Graham 1971, Graham 1998a, Facco et al. 2021) and molecular phylogenetic studies that revealed the artificiality of C. sect. Brachyandra ( Graham et al. 2006, Barber et al. 2010, Cavalcanti, pers. comm.). In the revision of C. sect. Brachyandra, Graham (2017) excluded both species from the taxonomic treatment.

Killeen & Schulemberg (1998) and Graham et al. (2014) refer C. tenuissima to Bolivia, based on the specimen “ Killeen & Peña 7178 ” deposited in MO. In the taxonomic revision of C. sect. Euandra subsect. Oidemation ( Graham & Cavalcanti 2013) , the identification of this material was corrected to C. luteola Graham & Cavalcanti (1999b: 303) , since the plant has yellow flowers and xylopodium, among other diagnostic characters.

Koehne (1877) described C. tenuissima based on two collections by W.J. Burchell (n° 8487 and 8533-2), collected in “ Porto Real, Goyaz [Goiás]”. Currently, the city is called Porto Nacional, which belongs to the state of Tocantins, after the division of the state of Goiás in 1989. Cuphea tenuissima is lectotypified here under “ Burchell 8533-2 ”, a specimen deposited in K composed of three individuals with flowers and fruits. In 1997, S.A. Graham designated this material as a lectotype by a note on the exsiccate, but it was never published.

Figures

FIGURE 16. A–G. Cuphea tenuissima. A. Branches with flowers; B.Abaxial surface of the leaf, margin strongly revolute to the midvein; C. Detail of raceme; D. Floral tube in lateral view, without petals; E. Floral tube in longitudinal-dorsal section, without petals; F. Pistil; G. Seed.A, C: Simon et al. 2699; B: Silva et al. 28; D–E: Cavalcanti et al. 2263; F: Pereira-Silva & Moreira 14958; G: Lima et al. 66. Scale bar. B, F, G: 1 mm; D–E: 2 mm. Photos. A, C: Marcelo Simon.

FIGURE 20. Geographical distribution of Cuphea auriflora, Cuphea inaequalifolia and Cuphea tenuissima.