Cuphea araguaiaensis M. G. Facco & T. B. Cavalcanti 2023, sp. nov.
Creators: name: Facco, Marlon Garlet
name: Cavalcanti, Taciana Barbosa
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Lythraceae
Cuphea
Cuphea araguaiaensis

description: 3. Cuphea araguaiaensis M.G.Facco & T.B.Cavalcanti, sp. nov.
Type:— BRAZIL. Mato Grosso: Alto Araguaia, entroncamento da estrada vicinal com a MT-100, Araguainha, km 29, 16º57’56”S, 53º05’12”W, 550 m, 03 April 2018, Pereira-Silva, Pereira & Facco 17010 (holotype CEN [00108603]!, isotypes K!, MO!, RB!, UFMT!). Figs. 7A–G, 19.
Diagnosis:— Cuphea araguaiaensis morphologically resembles C. ericoides, C. laricoides and C. paralarix, classified in C. sect. Trispermum s.l., but differs mainly by the erect habit (vs. decumbent in C. laricoides), branches with brachyblasts (vs. absent in C. ericoides) covered by short, erect eglandular and one-armed cystolithic appressed trichomes (vs. one-armed trichomes absent in C. ericoides), opposite leaves (vs. 3(–5)-verticillate in the three species), with strongly revolute margins (vs. plane margins in C. ericoides and C. paralarix), and purple petals (vs. yellow petals in C. paralarix).
Subshrubs 50–150 cm tall; stems erect, indumentum pubescent and strigose, eglandular erect and one-armed trichomes; internodes 0.5–1 cm long; brachyblasts present. Leaves opposite, coriaceous, sessile, blades 2–6 × 0.5– 0.7 mm, linear, rarely narrow-ovate, apex acute, base truncate, margin strongly revolute, indumentum strigose on both surfaces, with one-armed trichomes; hyphodromous. Racemes ca. 15 cm long, frondose, simple to compound, elongated, indistinct; bracts similar to leaves, pairs subequal. Flowers alternate; pedicels 3–4 mm long; bracteoles 1.3–1.8 mm long, narrow-ovate to ovate; floral tubes 6.4–7.4 mm long; spur obtuse, deflexed; outer surface purple in dorsal region, green ventrally, indumentum strigose and glandular, one-armed trichomes, and glandular trichomes ca. 0.3 mm long; inner surface villous behind stamens, pilose in spur region; petals 6, purple, subequal, two dorsal ca. 3.1 × 0.7, narrow-obovate, four ventral ca. 4 × 1.3 mm, obovate; stamens free in the upper third of the floral tube, five antesepalous exserted, four antepetalous subexserted; pistil 4.8–6.8 mm long; ovary pilose in the apical portion; style glabrous; ovules 3; nectary 0.6–0.7 × 0.7–0.8 mm, deflexed. Seeds 1–3, 1.7–1.8 × 1.5–1.6 mm, obovate, apex obtuse to truncate, base slightly acute, margin obtuse.
Phenology: —Collected with flowers and fruits in March, April, and December.
Distribution and habitat: — Brazil, in southern Mato Grosso state (Fig. 19); near rivers, on sandy soils, and on sandstone outcrops in “cerrados rupestres”; 500–630 m elev.
Conservation Status: — Cuphea araguaiaensis was categorized as Data Deficient (DD). This classification was influenced by the low number of specimens found, leaving it unclear whether the species has a sampling deficit or is rare in the region.
Etymology: —The epithet alludes to the occurrence of the species in the Upper Araguaia region, in the Araguaia river basin.
Paratypes: — BRAZIL. Mato Grosso: Alto Garças, estrada de terra direç ã o Alto Garça-Vila Diamantino, riacho (temporário) Forminha, ca. 56 km sentido Vila Diamantino, 19 December 1992, Silva & Rodrigues-Júnior 617 (SJRP image!); Ponte Branca, Fazenda S ã o Jo ã o, no córrego próximo à sede da fazenda, 16°39’45”S, 53°04’21”W, 23 December 2013, Francener et al. 1415 (SP!); Poxoréu, margem esquerda do Ribeir ã o Corguinho, Km 60, estrada Poxoréu-Juscimeira, 15º42’00”S, 54º18’15”W, 18 March 1978, Macêdo et al. 825 (INPA!).
Cuphea araguaiaensis is recognized by the presence of brachyblasts on its branches (Fig. 7B), by the opposite, linear leaves with strongly revolute margins (Fig. 7C), and by the purple petals. Small populations were recorded in southern Mato Grosso state, associated with streams, on sandy soils and sandstone outcrops in “cerrados rupestres”. Previously identified as a disjunct population of C. ericoides, it is being described here as a new species with the support of phylogenetic analyses based on molecular data (Facco, unpublished data). In these analyses, C. araguaiaensis is related to C. laricoides and C. paralarix, which also share brachyblasts on the branches (Figs. 12B, 13I), but are genetically differentiated from each other, and contrast in morphology, geographic distribution and habitat.
Cuphea ericoides differs from C. araguaiaensis by the absence of brachyblasts (Fig. 10B), by verticillate leaves with plane margins, and by the absence of strigose indumentum on the stem. The verticillate leaves also separate C. laricoides and C. paralarix from C. araguaiaensis. In addition, C. paralarix is distinguished by its plane margin leaves and yellow flowers (Fig. 13J), and C. laricoides, by its decumbent habit. Cuphea laricoides is distributed from the state of Maranh ã o to the extreme north of Bahia, in vegetation with elements of Caatinga. Cuphea ericoides is found in Pernambuco, and in the Espinhaço Range of Bahia and Minas Gerais. Cuphea paralarix has a wider distribution, occurring from Maranh ã o to Minas Gerais.
Cuphea araguaiaensis was placed in C. sect. Trispermum s.l. for presenting the morphological synapomorphies of this section, such as 3 ovules, deflexed nectary, obtuse margin seeds, and pollen grains with thickened exine between the pores, a position confirmed by phylogenetic analyses (Facco, unpublished data).
description: Published as part of Facco, Marlon Garlet & Cavalcanti, Taciana Barbosa, 2023, Taxonomic Revision of Cuphea sect. Trispermum s. l. (Lythraceae), pp. 1921-1935 in Phytotaxa 588 (1) on pages 1921-1935, DOI: 10.11646/phytotaxa.588.1.1, http://zenodo.org/record/7751590