Orthophytum arcanum Leme 2020, sp. nov.
Creators: name: Leme, Elton M. C.
name: Ribeiro, Otávio B. C.
name: Souza, Fernanda Vidigal D.
name: Souza, Everton Hilo De
name: Kollmann, Ludovic J. C.
name: Fontana, André P.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Poales
Bromeliaceae
Orthophytum
Orthophytum arcanum

description: 5.1 Orthophytum arcanum Leme, sp. nov. (Fig. 15 A–G)
Diagnosis: — This new species has some morphological affinities with O. vagans and O. pseudovagans but clearly differs from both by stemless plants (vs. caulescent), leaf blades with smaller marginal spines (0.2–0.5 mm vs. 1–3.5 mm), sepals red (vs. white or whitish), and petals acute (vs. obtuse-cucullate).
Type:— BRAZIL. Minas Gerais: Conselheiro Pena, near the top of the Pico do Padre Angelo, 1441 m elevation, 19º18’59” S, 41º34’44” W, September 2015, R. Vasconcelos Leitão s.n., fl. cult. E. Leme 9093 (holotype RB!).
Description: —Plants stemless, flowering 5–6 cm high, propagating by stolons of 6–9 × 0.25–0.3 cm, rigid. Leaves 10–12 in number, densely arranged, spreading; sheath subreniform, ca. 0.7 × 1.6 cm, greenish, inconspicuously lepidote to glabrous, corrugate and spinulose in distal part; blade narrowly triangular, attenuate, 9–10 × 1–1.2 cm, coriaceous, channeled toward the apex, glabrous, yellowish-green to reddish, abaxially nerved, margins densely spinulose; spines triangular, antrorsely curved, reddish-castaneous, 0.2–0.5 mm long, 1.5–2 mm apart. Inflorescence pseudosimple to inconspicuously compound, sessile or sometimes inconspicuously pedunculate, shortly corymbose, ca. 2 cm long (fertile part, excluding the petals), ca. 2.5 cm in diameter; primary bracts resembling the leaves, distinctly exceeding the flower fascicles, sometimes red near the base at anthesis; flower fascicles inconspicuous, sessile or nearly so, ca. 4 in number, ca. 2-flowered; floral bracts the basal ones somewhat resembling the leaves, exceeding to slightly shorter than the flowers, the upper ones and those in the flower fascicles triangular, acute to acuminate, ca. 15 × 6 mm, ecarinate, exceeded by the sepals, red, nerved, glabrous, thin in texture, margins densely spinulose. Flowers ca. 23 mm long, sessile, odorless; sepals narrowly lanceolate, attenuate to caudate, ca. 14 × 3 mm, free, entire, red, thin in texture, glabrous, carinate mainly towards the apex; petals narrowly spathulate, acute, ca. 17 × 4 mm, free, white, bearing inconspicuously and sparsely glandular trichomes, erect except for the suberect distal portion, forming a subtubular corolla, bearing 2 appendages; petal appendages ca. 3 mm above the base, sacciform, margins recurved, irregularly scalloped-crenulate; filaments unequal in length, terete, the antesepalous ones ca. 12 mm long, free, the antepetalous ones ca. 10 mm long, adnate to the petals for ca. 3 mm; anthers ca. 3 mm long, base bilobed, apex obtuse, dorsifixed at 1/4 of its length above the base; pollen broadly ellipsoidal, ca. 45 μm long, sulcate, the sulcus broad, sparsely covered with small exine elements, margins indistinct, exine reticulate; ovary subclavate, trigonous, ca. 6 × 4 mm, white, glabrous; epigynous tube inconspicuous; stigma simple-patent, lobes spreading, transversely U-shaped, elongated, distinctly longer than broad, white, papillate; placentation apical; ovules many, obtusely apiculate. Fruits not seen.
Distribution, habitat and conservation:— Orthophytum arcanum is known from the type locality only, where it lives near the top of the Pico do Padre Angelo (Fig. 15 A), about 1441 m elevation, in the county of Conselheiro Pena. It grows saxicolous in sun exposed to partially shady spots in the Campos Rupestres (Fig. 15 B–C), forming small groups of individuals. Only one small population with few individuals is known and further efforts to locate it in other mountains nearby, like Pico da Aliança in county of Alvarenga, were not successful. Considering the current knowledge about the species, it must be considered critically endangered (CR) on the basis of the “A.1. c + d” and “B. 2. a. + b. i to iv” criteria adopted by IUCN (2012).
Etymology: — The name of this new species is based on the Latin word “ arcanum ”, meaning mysterious, enigmatic, as a reference to its outlier status due to an unique combination of morphological characters and geographical range in the Atlantic Forest domain.
Observations:— Orthophytum arcanum is an outlier species without clear morphological affinity with any known species, like the other two species that are endemic to the same type region, O. roseolilacinum Leme (2015: 284), the single member of subg. Krenakanthus Leme, S. Heller & Zizka (2017: 75), and O. vasconcelosianum Leme (2015: 287), a member of subg. Orthocryptanthus Leme, S. Heller & Zizka (2017: 77).
Initially, we considered the possibility of this new species being a member of Sincoraea Ule (1908: 191), and so we exemplified the sacciform type of its petal appendages (Fig. 15 F) in Leme et al. (2017: 44, fig. 21 D) as “ Sincoraea sp. nov. (SAC, Leme 9093)”. However, the combination of geographical and morphological features of O. arcanum recommends its inclusion in Orthophytum subg. Capixabanthus rather than in Sincoraea, despite some discordant characters, like stigma simple-patent with longer and papillate lobes (Fig. 14 G), neither simple-dilated with broadened, densely papillate lobes as in Orthophytum subg. Capixabanthus, nor simple-erect with more compact, not papillate or inconspicuously papillate lobes as in Sincoraea.
The sessile, sometimes simple inflorescence, the inner leaves and primary bracts brightly colored at the base at anthesis and the sacciform petal appendage in some species of Orthophytum subg. Capixabanthus are also reported for members of Sincoraea. However, subg. Capixabanthu s differs from Sincoraea by plants distinctly caulescent (vs. always stemless) or when stemless, then inflorescence pedunculate (vs. never pedunculate), inner leaves, and primary bracts concolorous (vs. always forming a colorful ring around the inflorescence) or when forming a colorful ring around the inflorescence, then plants long caulescent (vs. always stemless) and petals obtuse-cucullate (vs. not obtuse-cucullate), or when not obtuse-cucullate, leaf rosette not flat at anthesis (vs. always flat). In addition, subg. Capixabanthu s contrasts with Sincoraea in having simple-dilated stigma type distinctly papillate (vs. simple-erect, without papillae or inconspicuously papillate), and pollen slightly smaller (35–40 μm vs. 40–45 μm in diameter), with reticulum formed by broad and flat muri with lumina or foveolae decreasing in size significantly towards the sulcus margins especially towards the apices, and the exine becoming almost psilate (vs. reticulum finely meshed with rather broad muri and lumina decreasing slightly to the sulcus margins). On the other hand, subg. Capixabanthus is endemic to Atlantic Forest related habitats in the central-northweastern region of Espírito Santo state, and in neighboring areas in Minas Gerais and Bahia states, mainly in the region of the three border between these states, while Sincoraea is restricted to the Campos Rupestres of the Septentrional Plateau of the Espinhaço Range in Minas Gerais and Bahia states.
This new species has some morphological affinities with O. vagans Foster (1960: 59) and O. pseudovagans Leme & L. Kollmann (2007: 155) but clearly differs from both by plants stemless (vs. caulescent), leaf blades with smaller marginal spines (0.2–0.5 mm vs. 1–3.5 mm), inflorescence sometimes inconspicuously pedunculate (vs. always sessile), sepals glabrous (vs. distinctly lepidote), red (vs. white or whitish), and petals acute (vs. obtuse-cucullate).
description: Published as part of Leme, Elton M. C., Ribeiro, Otávio B. C., Souza, Fernanda Vidigal D., Souza, Everton Hilo De, Kollmann, Ludovic J. C. & Fontana, André P., 2020, Miscellaneous new species in the " Cryptanthoid complex " (Bromeliaceae: Bromelioideae) from Eastern Brazil, pp. 157-202 in Phytotaxa 430 (3) on pages 191-193, DOI: 10.11646/phytotaxa.430.3.2, http://zenodo.org/record/13876272