Dichorisandra rigidifolia M. J. Silva & Aona, 2022

Silva, Marcos José Da & Aona, Lidyanne Yuriko Saleme, 2022, Dichorisandra rigidifolia (Commelinaceae), a new species from Cerrado of Goiás, Brazil, Phytotaxa 561 (1), pp. 95-103 : 96-101

Dichorisandra rigidifolia M. J. Silva & Aona , sp. nov., Figures 1A–R , 2A–J .

Type:— BRAZIL. Goiás: Niquelândia, Reserva Particular de Desenvolvimento Sustentável Legado Verdes do Cerrado, Núcleo Engenho , Área do Coimbra , Imediações da Caverna do Timbó , cerrado denso de encosta de morro, cerca de 100 metros a partir da lateral esquerda da Caverna do Timbó, solo argilo-arenoso, 14°36’44”S, 48°28’51’’W, 626 m elev., 28 January 2021 (fl, fr), M.J. Silva, I.S. Santos & B.R. Pereira 11706 (holotype UFG!; isotypes CEN!, HURB!, RB!, UB!, UFG!) .

Diagnosis:—This species has unique features in Dichorisandra , including erect habit, leaves firmly chartaceous, bracts of the cincinni and bracteoles persistent, flowers with petals lilac or pinkish from the middle third; and globose, blackish, and smooth capsules.

Description:— Herbs 1.15–1.85 m tall, terricolous or rupicolous, always erect; stems 0.9–2.5 cm diam. at the base, cylindrical, branching from the upper third, glabrous, including the outer surface of the sheaths at the base of the branches, the abaxial surfaces of the leaves, external surfaces of the sepals, cincinnus bracts, bracteoles, and buds; internodes 2.5–4.5 cm long. Leaves distichous alternate, congested at the ends of the main stem or its ramifications; sheaths 2–2.1 cm long, longitudinally striated, sheaths at the base of the branches 2.1–5 cm long, acuminate at the apex, glabrous or glabrescent, non-ciliated, green, petiole indistinct or up to 2 mm long, green, slightly sulcate; blade (5.5–)8– 14.1 × (2.6–) 3–5.3 cm elliptic, ovate-elliptic, oblong-elliptic, firmly chartaceous, base conspicuously asymmetric, apex acuminate, margins entire, non-ciliated, glabrous or sometimes glabrescent in the region immediately near the petiole on the abaxial surface, flat. Inflorescence 5.5–7.5(–11) cm long, terminal, erect, main and secondary axes tomentulose; leaf at the base of the inflorescence not differentiated from the others; peduncle 1.5–3.8 cm long; cincinnus peduncles 2.5–3 mm long, decreasing towards the apex; cincinni 9–13(–22), laxly distributed, (3–)6–7 flowered each; bracts of the cincinnus 12–15 × 2.1–2.2 mm, parallel to the peduncles of the cincinnus, lanceolate, decreasing towards the apex, glabrous, ciliated, persistent; bracteoles 5–5.1 × 2.9–4 mm, triangular or deltoid, glabrous, ciliated in the lower third or apex, persistent. Flowers staminate or bisexual, 1.85–1.9 × 1.9–2 cm, zygomorphic due to the position of the stamens; pedicel 4.2–5 mm long, green, sparsely pubescent; floral buds 7.8– 9.2 × 4.7–4.8 mm, oblongoid, ellipsoid or ovoid, glabrous, lilac or pinkish, sometimes whitish at base and greenish at apex; sepals 11.4–11.6 × 4.3–5 mm, oblong, oblong-elliptic, cymbiform, membranous, margins entire, not ciliated, glabrous on both surfaces, white at the base and pink or lilac from the lower third; petals 13.2–13.3 × 9–12 mm, widely obtrullate or obovate, entire, apex obtuse, lilac or pink, basal third white; stamens 6, subequal; filaments 1.2–4 mm long, white; anthers 5.3–6 mm, connectives white, thecae lilac or pink, with 2 apical pores, base sagittate; ovary 1.3–1.4 × 2–2.1 mm, globose, glabrous, smooth, with prominent mericarps; style 6.1–6.2 mm long, erect; stigma subcapitate, papillose. Capsules 1–1.2 × 0.9–1 cm, loculicidal, globose, green when immature, completely blackish, glossy, smooth when mature. Seeds 2 per locule, 3–4.2 × 3.5–4.8 mm, ovoid, dorsiventrally compressed, darkish, testa scrobiculate; hilum C-shaped, as long as the seed; embryotega semilateral; aril orange, spongy, thick.

Additional specimens examined (paratypes):— BRAZIL. Goiás: Niquelândia, Macedo , segunda bica do asfalto, solo laterítico, 14°23’48”S, 48°25’59”W, 830 m elev., 29 November 2006 (fl.), M. L. Fonseca et al. 1399 (IBGE, UEC, US) ; Reserva Particular de Desenvolvimento Sustentável Legado Verdes do Cerrado, Núcleo Engenho, Área do Córrego da Anta acessado pela Cabeceira dos Macacos, 14°40’55”S, 48°27’12”W, 727 m elev., 04 December 2020 (fl.), M. J. Silva & A. A. Alonso 11369 (UFG), 11370 (UFG) ; ibd., Reserva Particular de Desenvolvimento Sustentável Legado Verdes do Cerrado , Núcleo Engenho, Área do Coimbra , imediações da Caverna do Timbó , cerrado denso de encosta de morro em afloramento de rochas lateral a caverna, solo areno-argiloso pedregoso, 28 January 2021 (fl, fr), M. J. Silva, I. S. Santos & B. R. Pereira 11692 (UFG), 11693 (UFG), 11694 (UFG) ; ibd., cerca de 100 metros a partir da lateral esquerda da Caverna do Timbó , em encosta de morro, solo areno-argiloso pedregoso, 28 January 2021 (fl., fr.), M. J. Silva, I. S. Santos & B. R. Pereira 11706 (UFG), 11708 (UFG), 11709 (UFG) ; ibd., cerca de 100 metros da lateral esquerda da caverna do Timbó e 120 metros a partir da subida do morro, em afloramentos de rochas, 14°33’07”S, 48°30’03”W, 684 m elev., 19 February 2021 (fl.), M. J. Silva, I. S. Santos & B. R. Pereira 11759 (UFG), 11760 (UFG) ; ibd., 150 metros a esquerda da lateral da Caverna do Timbó , aproximadamente 160 metros a partir da base do morro, 14°33’07”S, 48°30’03”W, 684 m elev., 19 February 2021 (fl., fr.), M. J. Silva, I. S. Santos & B. R. Pereira 11877 (UFG), 11880 (UFG), 11895 (UFG) ; ibd., cerrado denso em topo de morro, próximo a afloramentos de rochas, 14°33’10”S, 48°29’59”W, 649 m elev., 19 February 2021 (fl.), M. J. Silva, I. S. Santos & B. R. Pereira 11881 (UFG), 11882 (UFG), 11900 (UFG), 11901 (UFG) ; área aberta de floresta seca, 14°33’0.75”S, 48°30’03”W, 673 m. a.s.l. 19 February 2021 (fl., fr.), M. J. Silva, I. S. Santos & B. R. Pereira 11884 (UFG) ; ibd., primeira estrada lateral a Caverna do Timbó , cerca de 150 metros, na lateral esquerda em encosta de morro, cerrado denso, areno-pedregoso, 14°32’55”S, 48°30’17”W, 599 m elev., 19 February 2021 (fl., fr.), M. J. Silva, I. S. Santos & B. R. Pereira 11921 (UFG), 11922 (UFG) ; ibd., 350 metros a partir da primeira estrada a direita da caverna do timbó no sopé do morro a direita, 14°32’58”S, 48°30’24”W, 612 m elev., 27 March 2021 (fl., fr.), M. J. Silva, A. A. Alonso & I. S. Santos 12166 (UFG) ; ibd., Área do Zé Gordo , primeiro afloramento de rochas cerca de 1, 1 km a partir da estrada que leva a casa abandonada, 14°20’28”, 48°13’58”, 687 m elev., cerrado denso 20 February 2021 (fl., fr.), M. J. Silva, I. S. Santos & B. R. Pereira 12011 (UFG), 12012 (UFG), 12013 (UFG), 12014 (UFG) .

Distribution and habitat: —Species collected until now in the municipality of Niquelândia, Goiás State, Brazil ( Fig. 3 ). It grows in “ cerrados típicos”, in the Macedo region, and in “ cerrado denso ”, in level areas, on slopes or hilltops, in the Legado Verdes do Cerrado Private Sustainable Development Reserve, on sandy-clay or sandy-stony soils near rock outcrops, or in rock crevices between 612 and 830 meters of elevation.

Phenology: —Collected with flowers from November to March and with fruits in February and March.

Etymology:—The specific epithet “rigidifolia” alludes to the rigid aspect of the leaves of the new species when compared to congeners.

Preliminary conservation status: —Species classified as Endangered, EN, B1ab(iii, v), B2ab(ii, iv, v), C(i) for having an Extent of Occurrence and Area of Occupancy of 443,609 km 2 and 144,000km 2 respectively, as well as a restricted distribution. It forms populations of less than 250 mature individuals growing in areas of difficult access, such as slopes or hilltops, but surrounded by soybean plantations or devastated savannah patches.

Morphology and relationships: — Dichorisandra rigidifolia can be recognized by its herbaceous habit, always erect, between 1.1–1.85 m tall, glabrous stems branching from the upper third, robust (0.9–2.4 cm diam.), branches neither pendulous nor supporting, leaves alternate and distichous, firmly chartaceous, ovate, widely ovate-oblong or combinations, with asymmetrical base, glabrous on both surfaces or with trichomes only at the base of the abaxial surface, petiole, and sheath, inflorescences with cincinni bracts and persistent bracteoles, flowers with glabrous sepals, lilac or pink petals from the middle third, androecium with six fertile stamens with thecae lilac or pink with two apical pores, in addition to globose, completely blackish and smooth capsules.

It shares with D. densiflora Ule (1908: 70) an alternating phyllotaxis and leaves glabrous or with sparse trichomes only on the abaxial surface, inflorescences always erect with persistent bracteoles, and globose capsules. Dichorisandra densiflora , however, has unbranched stems (vs. branched in the upper third in D. rigidifolia ), leaves with ciliated margins (vs. non-ciliated), sheaths 1.8–3 cm long, glabrous or pubescent only in the region opposite the leaf insertion (vs. 2–2.1 cm long, uniformly tomentellous), cincinni with (5–)16–18 flowers (vs. (3–)6–7), cincinni bracts 16–21 × 1–1.5 cm (vs. 12–15 × 2.1 –2.2 cm), bracteoles 2.9–3 × 2–2.5 cm (vs. 5–5.1 × 2.9–4 cm), flowers with pedicel ca. 2 mm long, petals purplish-blue, and pollen sacs blue (vs. flowers with pedicel 4.2–5 mm long, lilac or pink petals and pollen sacs), gynoecium with capitate and trilobed stigma (vs. subcapitate), in addition to largely ellipsoid or obovoid capsules 3-ribbed (vs. globose and smooth capsules).According to Aona (2008), D. densiflora is restricted to the South American Amazon Domain of Peru and Brazil (Acre and Amazonas States), while D. rigidifolia is restricted to the Cerrado Phytogeographic Domain, and only known from Goiás State.

Other Dichorisandra species can be confused with D. rigidifolia , such as D. amabilis Grant (2000: 117) , endemic to Central America ( Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama, and southern Mexico), and D. ulei Macbride (1931: 8) from northern South America ( Peru, Ecuador, Bolivia, and Acre in Brazil), because they share an erect habit, their vegetative parts are usually glabrous, their leaves are uniformly green with asymmetric bases and acuminate apices, and they have erect and terminal inflorescences with basal leaves not differentiated from the others. However, associated with the distributions of the taxa under discussion, the characters listed in the Table 1 serve to differentiate them.

Finally, according to Aona & Amaral (2020), Dichorisandra hexandra , D. perforans , and D. pubescens are found in Goiás State. The former species, however, is an herb, usually scandent, with a delicate glabrous or glabrescent stem, leaves generally symmetrical and membranaceous, and flowers with blue petals and pollen sacs, and (usually) green sepals; the second has inflorescences generally emerging from the sheath near the base of the stem; the latter species has a tomentose stem, up to 50 cm tall, with pendulous terminal branches, bifacial, and indumented on both surfaces, and flowers with petals and pollen sacs blue, and indumented sepals. Those characters, as mentioned above, are not seen in D. rigidifolia .

Figures

FIGURE 1. Dichorisandra rigidifolia. A. Flowering branch; B. Leaf. C. Detail of leaf base and sheath. D. Detail of leaf margin; E and F. Cincinnus bract. G. Detail of the indumentum on the abaxial surface of the bracts of the cincinnus; H. Bracteole, note the margin sparsely ciliate. I. Flower bud. J. Flower in ventral view. K. Petals, L. Sepals. M. General aspect of the stamen in staminate flowers. N. Detail of a monocline flower with some of the sepals and petals removed. O. Stamens, note their size variations. P. Gynoecium. Q. Detail of the stigma. R. Capsule. (Drawn by Cristiano Gualberto from M. J. Silva, I. S. Santos & B. R. Pereira 11706).

FIGURE 2. Dichorisandra rigidifolia. A. Habitat. B. Habit with inflorescence detail. C. Vegetative branch, note the alternate leaves. D. Detail of the glabrous stem and rest of the leaf sheath. E. Fertile branch. F. Inflorescence showing cincinni and floral buds. G. Flower in ventral view. H. Cincinnus in lateral view. I. Portion of the cincinnus showing the persistent bracts. J. Capsules, note the smooth surface.

FIGURE 3. Distribution of Dichorisandra rigidifolia. A Map of Brazil, highlighting Goiás State in gray; B Map of Goiás State, its limits and elevation variations. C Municipality of Niquelândia, (dotted area) with the species distribution points.Abbreviations for the Brazilian states (BA, Bahia; GO, Goiás; MG, Minas Gerais; MS, Mato Grosso do Sul; MT, Mato Grosso; TO, Tocantins) and Federal District (DF).