Dichorisandra rhizantha Aona, 2022

Aona, Lidyanne Y. S., Souza, Everton Hilo De, De Almeida Júnior, Railson A. C., Marinho, Lucas C., Bittrich, Volker & Do Amaral, Maria Do Carmo E., 2022, Dichorisandra rhizantha (Commelinaceae), a new morphologically unusual species from Bahia, Brazil, Phytotaxa 538 (3), pp. 257-264 : 258-262

Dichorisandra rhizantha Aona , sp. nov. ( Fig. 2 ).

Diagnosis: — Dichorisandra rhizantha is distinguished from its congeners by the well-developed indument on both sides of the leaf blades, by the flowering branches arising always directly from the rhizome and the vegetative branches arising axillary from the leaf sheaths below the terminal inflorescences, and by the cylindrical capsules with a smooth epicarp.

Type:— BRAZIL. Bahia: Cruz das Almas, Mata da Cazuzinha , 12°40’01.2”S 39°06’25.5”W, 5 January 2021, L.Y.S. Aona et al. 5921 (holotype HURB!; isotypes ALCB!, UEC!) .

Description: — Plant erect, first unbranched and later branching by axillary stems arising from the leaf sheaths below terminal inflorescences, 0.6‒1 m tall. Stem longitudinally striate in sicco, whitish pubescent with 2‒3 mm long trichomes, 2‒2(‒3) cm diam. at the base, ca. 1.5 cm diam. at the apex, internodes 16‒18 cm long at the base, often short towards the apex. Leaves distichous, sheaths 2.5‒3 cm long, pubescent, lower sheaths caducous, showing pale vinaceus streaks and white spots, distally covered with sparse short trichomes, 5 mm long, brownish to slightly white; basal leaves with 9‒10 mm long petiole, pubescent, apical leaves sessile; leaf blades lanceolate, 16‒19.5 × 3‒3.5 cm, discolorous, abaxial face light green to purplish, adaxial face dark green, primary vein whitish on the adaxial face in vivo, pilose on both sides, trichomes 1 mm long, whitish, margin ciliate, base attenuate, apex acuminate. Flowering branch erect, arising directly from the rhizome and later axillary vegetative branches arising perforating the leaf sheaths; peduncle 2‒4.5 mm long, greenish, pubescent, trichomes 2‒3mm long, whitish; cincinnus pedunculate, peduncle 1‒1.5 mm long, pubescent with 24‒45(‒68) cincinni, with 3–5 flowers each, bracts linear to lanceolate, 7–9 × 3 mm, reduced towards the apex, oriented parallelly to the cincinni rachis, apex curved, greenish, turning scarious over time, abaxial side pubescent, trichomes 1‒1.5 mm long, whitish, adaxial side glabrous, margin ciliate, bracteoles ca. 3 × 2 mm, scarious, abaxial side pubescent, margin ciliate. Flowers either bisexual or male, deliquescent, androecium slightly zygomorphic, 1.5–1.8 cm wide, pedicel pubescent, green, ca. 2mm long, floral buds ovoid, 0.7– 0.8 × 0.2– 0.3 mm, pubescent; sepals ovate, 0.8–1.4 × 0.2– 0.4 mm, greenish, pubescent; petals obovate, 1.3–1.4 × 1–1.1 cm, distal two thirds blueish, proximal third whitish; stamens 5, slightly unequal, directed towards the center and upper part of the flower, staminode reduced, ca. 1 mm long or staminode linear, ca. 0.5 mm long, filaments 1–1.5 mm long, erect, anthers 4–5 mm long, oblong, slightly sagittate at base, whitish with purplish apex, opening introrsely with longitudinal slits (functionally poricidal), base sagittate; ovary 1.1–1.2 × 0.9 mm, globose, ovules 6–7 per cell, greenish-yellowish, glabrous and smooth; style 2.4–2.5 mm long, whitish, bluish to purplish in the upper third, erect, apex curved, stigma capitate. Capsule cylindrical, 2.1–2.5 × 0.4–0.7 cm, greyish-brownish, glabrous. Seeds 6–7 per locule, ellipsoid to oblongoid, 3–4.8 × 3 mm, dorsiventrally compressed, brown to dark brown; aril whitish to brownish (when fruit open).

Paratypes: — BRAZIL. Bahia: Cachoeira, Morro Belo, Vale entre Rios Paraguaçu e Jacuípe , 40/ 120 m, 39˚05’S, 12˚32’W, December 1980, Grupo Pedra do Cavalo 973 ( HUEFS, NY) ; Cachoeira, ibid., Grupo Pedra do Cavalo 986 ( ALCB, EAC, NY) ; Cachoeira, trilha para o Poço da Mãe d’Água , 04 November 2009, S.F. Conceição 926 et al. ( HURB) ; Cachoeira, Fazenda favela, propriedade do Joca , 218 m, 12˚34’24,2”S, 38˚59’14,7”W, 24 March 2015, W.O. Fonseca 117 et al. ( HURB) ; Castro Alves , remanescente florestal (florestas e aquáticas), 10 December 2018, M.R. Sampaio 17 et al. ( HURB) ; Castro Alves, Serra da Jiboia , trilha pela mata dentro da fazenda particular D. Cota, 10 December 2018, L.Y.S. Aona 4873 & turma de Zootecnia ( HURB) ; Cruz das Almas, Mata da Cazuzinha , 11 February 2012, A. Queiroz Neto s.n. ( HURB) ; ibid., 05 February 2018, M.L. Guedes 30263 ( ALCB) ; ibid., Mata EBDA, 27 March 2010, A.L. Cortês 232 ( HUEFS) ; Muritiba, Rio Capivari, Cachoeirinha , margem da cachoeira, 6 February 2021, L.Y.S. Aona 5922 et al. ( HURB) ; Jequié, assentamento Faz. Brejo Novo, Bairro Mandacarú , seguindo a Av. Otávio Mangabeira, virando a Av. Exupério Miranda e seguindo direto, Morro em frente ao laguinho e barragem, atrás da casa branca e azul, 25 January 2017, L.C. Marinho & K.M.Pimenta 1233A ( HURB) ; Jequié, Fazenda Ituíba , 26 September 2012, G.S. Silva 111 & M.A. Chagas ( HUESB) ; Jequié, km 19 – Cajueiro , 9 November 2006, M.N. Oliveira 18 ( HUESB) ; Jequié, Serra do Castanhão, 14,5 km of Jequié on BR 116 to road (at Churrascaria Corujão ), then 7,2 km, 775 m, 13˚56.522’S, 40˚11.486W, 23 October 2001, W.W. Thomas 12554 et al. ( NY, UEC) ; Santa Terezinha, Povoado de Pedra Branca, Trilha em direção a Serra da Pioneira , 12 December 2016, T.N. Alves et al. 01 (two sheets, HURB) .

Etymology: — The specific epithet is a reference to the characteristic flowering branches arising directly from the rhizome apparently perforating the sheaths of the leaves on the axillary branches, with leaves absent or with only a few developing later. These are unusual characters in the genus and easily allow the identification of the species, especially also with herbarium material.

Phenology:—Field studies by Almeida Júnior (2020) in the Mata da Cazuzinha Forest Park (Cruz das Almas, Bahia) showed that this new species is flowering from November to early March and the fruiting period occurs from December to March. The same data were observed on herbarium specimens.

Distribution and habitat: — Dichorisandra rhizantha is endemic to eastern Bahia state (Cachoeira, Castro Alves, Cruz das Almas, Jequié, Muritiba and Santa Terezinha municipalities), Northeast Brazil and appears to be restricted to transitional areas between the Caatinga and Atlantic Forest domains ( Fig. 2 ). The specimens are distributed in remnants of seasonal semi-deciduous forests.

Conservation status: — The suggested conservation status for Dichorisandra rhizantha is Endangered EN B1a(iv)+2ab(i,iii). According to current records, the species has 10 populations distributed along six municipalities [B1ab(iv)]. Although the number of populations indicates the species as Vulnerable (≤10), the species has an Extent of Occurrence (EOO) of 3,650 km 2 and an Area of Occupancy (AOO) of 32 km 2 [B1a+2b(i)]. All specimens of Dichorisandra rhizantha were collected from forest remnants in urban areas or rural properties. The type locality (Mata da Cazuzinha Florest Park, Cruz das Almas, Bahia, see Fig. 2A ) is a protected park surrounded by an urban area and suffers constant human interference such as garbage deposition and forest fire (the last occurred in February 2021), this being the only protected area where D. rhizantha occurs [B2b(iii)]. The other specimens examined were collected also in forest fragments, but in villages and private rural properties. Although at least three populations out of 10 have been visited, it is not possible to use the number of mature individuals to infer the degree of threat, since D. rhizantha loses its aerial parts in the dry season, maintaining only its rhizomes and the tuberculous root storage organs. Two populations of the Cruz das Almas municipality had among 20 and 30 individuals, one of Jequié’s populations had only about 10 mature individuals.

Observations: — Dichorisandra rhizantha can be identified by its densely pubescent leaves, flowering branches arising directly from the rhizome and by the cylindrical, glabrous capsules ( Table 1 ). The first inflorescence develops close to the ground after a few leaves reduced to their sheaths. Directly below the terminal inflorescence, axillary branches arise. These can be either bearing normal leaves and end in another terminal inflorescence or directly produce another inflorescence ( Table 1 , Fig. 3d ). This species is morphologically similar to D. hirtella Mart. ex Schultes f. ( Schultes 1830: 1184) by the dense pilosity on leaves, stems and calyx, but distinguished by the flowering branches arising always directly from the rhizome and producing inflorescences and leaves in the pattern described above while in D. hirtella the inflorescences develop terminally on main branches ( Table 1 ). Dichorisandra hirtella was first described as a variety of D. puberula Nees & Martius (1823: 13) and their taxonomic history is a little confusing also due to uncertainties concerning the collection localities of the German naturalist zu Wied-Neuwied.

This poorly known species was first described a variety of D. puberula based on material collected by zu Wied - Neuwied in Bahia, somewhere between Itabuna and Vitória de Conquista (Bahia). In the publication, the authors mentioned two varieties for the species, the variety α with glabrous sepals and the variety β with hairy sepals. Schultes f. (1830) recognized that there were two distinct species involved. He kept the variety α as D. puberula and raised the variety β to species status naming it D. hirtella . The holotype of the latter is deposited in BR and was identified as D. hirtella by Schultes f. himself (image available at http://www.botanicalcollections.be/specimen/ BR0000013326081). Seubert (1855) stated incorrectly that the specimen of D. hirtella was collected by zu Wied-Neuwied in December 1816 in Ilhéus. According to the holotype, however, it was collected in January 1817 and Ilhéus is not mentioned. In this month, Wied-Neuwied travelled ca. 170 km from Itabuna (“S. Pedro d’Alcantara”) westwards on the road named “Via Filisberti” in the direction of Vitória da Conquista (“Barra da Vareda” or Inhobim), where he arrived end of January. This road had been opened by some Tenente-Coronel Filisberto Gomes da Silva shortly before zu Wied-Neuwied travelled in the region, but was soon afterwards abandoned (see Moraes 2011). Nees & Martius (1823) had therefor correctly written only that the specimen of D. hirtella was collected “Circa viam Filisberti, Centurionis, mense Januario”. No specimens are known from the well-collected region of Ilhéus showing the characteristics of D. hirtella .

Dichorisandra rhizantha is also morphologically similar to Dichorisandra jardimii Aona & M.C.E.Amaral (2012: 6) , by the development of the inflorescence, but D. rhizantha has a smooth ovary and fruit surface (vs. ovary and fruit verrucose in D. jardimii ), leaves with dense pilosity on both sides (vs. leaf blades glabrous above, pilose beneath in D. jardimii ) ( Table 1 , Fig. 3 ).

Another Bahia species, Dichorisandra radicalis Nees & Mart. (1823: 11) , superficially resembles D. rhizantha in that it has inflorescences close to the ground, but D. radicalis presents axillary and not terminal inflorescences close to the base of the stem or up to 15 cm above the base of the stem (vs. flowering branches with terminal inflorescences arising from the rhizome in D. rhizantha ) ( Table 1 ).

Furthermore, Dichorisandra rhizantha can also be distinguished from D. radicalis in that it has an inflorescence of 24‒45(‒68) cincinni (vs. 10‒12 very congested cincinni), petals with white lower third (vs. petals with white lower half) ( Table 1 , Fig. 3 ).

Figures

FIGURE 2. Dichorisandra rhizantha. a. Habit. b. Sheaths, adaxial view. c. Sheaths, abaxial view. d. Stem with leaf sheath in detail. e. Leaf, adaxial surface. f. Detail of the indument present on the margin. g. Trichomes of the adaxial side of the leaf. h. leaf, abaxial surface. i. Detail of the indument present on the margin. j. Trichomes of the abaxial side of the leaf. k. Young flowering branch with flower buds. l. Flowering branch with open flowers. m. Bisexual flower. n. Sepal, adaxial view. o. Sepal, abaxial view. p. Petal, adaxial view. q. Petal, abaxial view. r. Detail of a bisexual flower with sepals and petals removed. s. Androecium with stamens and reduced staminode (sm), adaxial view. t. Androecium with stamens and reduced staminode (sm), abaxial view. u. Gynoecium with sepals, petals and stamens removed. v. Immature fruit. w. Capsule with seeds (se). Bars: b–e, h, k–r, v–w = 1cm; f–g, i–j = 200 µm, s-u = 1 mm.

FIGURE 3. Inflorescences of Dichorisandra rhizantha and similar species. a. Inflorescence of D. jardimii. b. Inflorescences of D. radicalis. In detail, a flower showing petals with white lower half. c–d: Dichorisandra rhizantha. c. Inflorescence branch. d. Flowering branches congested and vegetative branches arising at the base of very short internodes. In detail, petals with apical two thirds blueish, proximal third whitish.