Tillandsia mantiqueirae Paixão-Souza, N.G. Silva & R.J.V. Alves, 2021

Paixão-Souza, Bruno, Silva, Nílber Gonçalves Da, Guimarães, Alessandra Ribeiro, Alves, Ruy José Válka & Costa, Andrea Ferreira Da, 2021, Tillandsia mantiqueirae (Bromeliaceae), a New Species from Minas Gerais State, Brazil, Phytotaxa 525 (3), pp. 196-204 : 198-201

Tillandsia mantiqueirae Paixão-Souza, N.G. Silva & R.J.V. Alves , sp. nov. ( Fig. 1 , 2 A-D)

Tillandsia mantiqueirae shares carinate sepals and white petals with the closely allied T. nuptialis from which it differs by shorter leaf blades (5 cm vs. 10 cm); red peduncle bracts and floral bracts (vs. green); connate red sepals (vs. free green sepals); non-mechanical epidermal cell thickening (vs. mechanical); and a single celled trichome epidermis stalk (vs. multiple-celled).

Type:— BRAZIL. Minas Gerais: Alagoa, estrada a oeste da cidade. Paredão de rocha granítica, 1,345 m elevation, 22 June 2013, B . Paixão-Souza 201 (holotype R!) .

Plant rupicolous, caulescent, 25–35 cm long in flower, growing in clumps. Roots present. Stem 15–30 cm long, apically branching. Leaves ca. 30, curved upward secund, 6–8 cm long, polystichously arranged along the stem; sheaths 1.5–2 × 0.5 cm, narrowly ovate, densely lepidote; blades 4.5–6 × 0.5 cm, very narrowly triangular, involute, fleshy, covered by scales giving it a whitish color. Inflorescence simple, 9–15 cm long, 4–6 polystichous flowered; peduncle 5–10 cm long, exceeding the leaves, slender; peduncle bracts foliaceous, 2–3.5 cm long, the upper lanceolate, lepidote at the apex, reddish; rachis reddish. Floral bracts 1.5–1.8 × 0.9–1 cm, exceeding the sepals, oval, acuminate, carinate, sparsely lepidote, pink. Flowers 2.5 cm long, sessile; sepals 1.2–1.5 x 0.4 cm, obovate-lanceolate, apiculate, carinate, glabrous, pink, adaxial ones carinate and connate up to about ½ the length; petals 2.1–2.5 cm long, lingulate, obtuse, apical part spreading at anthesis, white; stamens included, ca. 11 mm long; filaments 7–8 mm long, free, flattened, plicate below the anthers; anthers 3 mm long, linear, basifixed; ovary 3–4 mm long, 2 mm in diameter, ovoidal; style 7 mm long; stigma simple-erect.

Distribution, habitat and phenology:— Known only from the type locality, a granitic cliff in the Alagoa municipality, southern Minas Gerais in southeastern Brazil. The species forms a dense population on the north-facing cliff, exposed to full sunlight, surrounded by pasture within an area of dense forest ( Fig. 2 A–D ; 3 ). Flowering in August.

Conservation status:— IUCN (2001): The provisory status of the species is Critically Endangered (CR) (B2abiii), because it is known from a single population which is surrounded by an area of extensive cattle grazing, and is not represented in conservation units. Furthermore, there are several large mining operations in the region of the only known population.

Etymology:—The specific epithet refers to one of the most expressive massifs in southeastern Brazil, the Mantiqueira mountain range.

Paratype:— BRAZIL, Minas Gerais, Mun. Alagoa, Morro do Morro, ca. 2 km a oeste da cidade. Paredão de rocha granítica, 1369 m elevation, 06/08/2009, R. J. V . Alves 7955 & N. G . Silva ( R!) .

Additional examined material of T. nuptialis :— BRAZIL, Rio de Janeiro, Montserrat, Pedra Paraibuna , P . I .S. Braga 1556 (Holotype RB!) .

Compared leaf anatomy:—Epidermis of the new species and T. nuptialis unistratified ( Fig. 4 A, B ); in T. nuptialis the internal periclinal and the anticlinal walls are similarly thickened, resulting in a small lumen ( Fig. 4 B, D, F ). In T. mantiqueirae the internal periclinal wall is thicker than the anticlinal, resulting in a much larger “U –shaped” lumen ( Fig. 4 A, C, E ). In both species the stomata and trichomes are sunken below the surface of the remaining epidermal cells ( Fig. 4 E, F ). The leaves are hypostomatic and the stomata are accompanied by substomatic chambers ( Fig. 4 E, F ). Peltate multicellular trichomes consisting of a stalk and a disc occur on both leaf surfaces; stalks consisting of a single cell in T. mantiqueirae and three cells in T. nuptialis ( Fig. 4 C, D ). The discs in both species are similar, with four large central cells surrounded by three layers, respectively with 8, 16 and 24 cells and by the wing, a final portion of the trichome composed of asymmetrically elongated cells ( Fig. 4 G, H ). Mesophyll: in both species the first layer below the epidermis consists of relatively small cells, translucid, tubular with thin, non-lignified walls in T. mantiqueirae ( Fig. 4 A, C, E ); slightly flattened, with thickened and highly lignified walls, forming a mechanical tissue in T. nuptialis ( Fig. 4 B, D, F ). Subtending the previous layer, a water storage parenchyma occurs below both surfaces ( Fig. 5 A, D ). The adaxial aquiferous parenchyma consists of elongated cells with undulating walls (concertini cells) ( Fig. 5 B, E ); in T. mantiqueirae these are disposed in 2-3 layers of cylindric cells, more elongated anticlinally, occupying more than half of the mesophyll ( Fig. 5 A ); in T. nuptialis these cells are isodiametric, appear in 3-4 layers and occupy less than half of the mesophyll ( Fig. 5 D ). The abaxial aquiferous parenchyma in T. mantiqueirae consists of 2-3 layers of continuous isodiametric cells interrupted only by the substomatic chambers, while in T. nuptialis these layers are less developed and are also interrupted by chlorenchyma ( Fig. 5 A, D ). The chlorenchyma is situated between the aquiferous parenchyma layers of both leaf surfaces and consists of juxtaposed isodiametric cells comprising 8-10 layers in T. mantiqueirae and 12-14 in T. nuptialis ( Fig. 5 A, D ). The vascular tissue within the chlorenchyma consists of a single series alternating wide and narrow collateral vascular bundles ( Fig. 5 A, D ) all of which have sclerenchyma caps adjacent to the xylem and phloem; in T. mantiqueirae these are less developed ( Fig. 5 C, F ).

Discussion:—The infrageneric delimitations within Tillandsia have been vehemently questioned for decades ( Gardner 1982, 1986; Till 1992, Spencer & Smith 1993, Beaman & Judd 1996, Espejo-Serna 2002), especially with molecular-based phylogenetic hypotheses that revealed the polyphyly of the genus and infrageneric taxa ( Barfuss et al. 2005). With the recent realignment of the subfamily Tillandsioideae , new circumscriptions of the subgenera of Tillandsia were recognized and new genera were described ( Barfuss et al. 2016). Tillandsia subg. Anoplophytum ( Beer 1854: 346) Baker (1887: 42) , as circumscribed by Smith & Downs (1977), proved to be polyphyletic and was split into three different lineages. The lineage containing the type species - Tillandsia stricta Sol. ex Sims (1813 : pl. 1529) - is highly supported and encompasses 33 species ( Barfuss et al. 2016) which share the simple inflorescences and polystichous flowers ( Paixão-Souza 2016). Most of them are endemic, rock-dwelling and often have extremely narrow distribution ranges, such as T. mantiqueirae and T. nuptialis , which are currently known only from their type populations, both being vertical granite cliffs facing north ( Figs. 2 , 3 ), thus highly exposed to solar radiation throughout most of the daytime. Some of the anatomic features, e.g. the well-developed aquiferous parenchyma, peltate scales densely covering the epidermis, the air channels typical of CAM plants are adaptations which enhance the chance of colonization on impermeable substrates highly exposed to sunlight ( Benzing 2000).

Within the Mantiqueira mountain range, T. nuptialis and T. mantiqueirae are separated by ca. 200 km, which could suggest they are conspecific ( Fig. 3 ). However, the morphological, anatomical, and phenological features ( Tab. 1 ) are solid evidence to keep them separate. Moreover, in a phylogenetic analysis molecular based of T. subg. Anoplophytum currently being conducted by the first author, both aforementioned species appear in the same clade related mainly to T. tenuifolia . Another species from that clade is T. hofackeri , endemic to the Caatinga of the Bahia state, which is also allied to T. mantiqueirae , but the latter presents larger dimensions and the populations are separated by more than 1000 Km ( Tab. 1 ). Plants of this group are long-caulescent and share simple inflorescences, green to pink bracts and white to bluish corolla. Comparative anatomy has proven to be a useful tool in finding additional distinctive characters useful for taxonomy, in several plant families and for the understanding of the ecology and biology of the taxonomic groups. The concept of metapopulation by De Queiroz (2007) also corroborates the arguments presented in support of the species presented here.

Tillandsia nuptialis is a little-known species, naturally endemic to only one granitoid massif. However, it is found for sale on web sites, possibly a product of illegal collecting for cultivation and sale, which may indicate a threat to the species. However, due to the vertical cliffs on which these plants thrive, the inherent difficulty in collecting them is a favorable point in their conservation. The questions remain are: how is a species so little known by science so readily commercialized? How many narrowly endemic Tillandsia species are in the same situation? Is the cultivation of rare plants, even if not legalized, also a form of conservation?

Figures

FIGURE 1. Tillandsia mantiqueirae. A. Habit. B. Inflorescence. C–D. Flower partly concealed by bract in natural position (C—open flower; D—bud). E. Extended floral bract. F. Extended sepals. G. Extended petals and stamens. H. Pistil. I. Anther.

FIGURE 2. Population of Tillandsia mantiqueirae (A–D), and T. nuptialis (E–F). A. General view of topotypic habitat. B. Cliff, ca. 1,350 m.a.s.l.. C. Population covering the granitic outcrop. D. Habit in situ. E. T. nuptialis population over the granitic outcrop from topotypic habitat. F. Habit in situ.

FIGURE 3. Location map of Tillandsia mantiqueirae, Alagoa, Minas Gerais State and T. nuptialis, Levy Gasparian, Rio de Janeiro State, Brazil.

FIGURE 4. Transversal sections of median leaf portions of T. mantiqueirae (A, C, E, G) and T. nuptialis (B, D, F, H). A–B (adaxial surface). Detail of the single-layered epidermis. A. Cells with “U-shaped” thickening and thin-walled cells in the subepidermic layer characterizing a non-mechanical tissue.B. high degree of thickening of the anticlinal and internal periclinal walls and secondary thickening of the subepidermal cells forming a mechanical layer. C–D (adaxial surface). C. Detail of trichome with single-celled stalk and central cell in disc. D. Detail of trichome with 3-celled stalk and a single central cell in the disc. E–F (abaxial surface). Details of stomata (arrows) and substomatic chambers. G–H. Frontal view of peltate trichomes. Abbr.: ep. epidermis; snml. subepidermal not mechanical layer; sml. subepidermal mechanical layer; *. stalk cells; dcc. disc central cell; sc. substomatic chamber; Scale bars: A–B—10 μm; C–H—5 μm. (Preparations and images by A.R. Guimarães).

FIGURE 5. Transversal sections of median portions of leaf laminas.A–C. Tillandsia mantiqueirae.D–F. T. nuptialis. A, D. General aspect of leaf lamina, with mesophyll consisting of aquiferous parenchyma and chlorenchyma. B, E. Detail of abaxial aquiferous parenchyma cells with undulating lateral walls resembling consertini. C, F. Detail of collateral vascular bundles with sclerenchymatic girders. Abbr.: ap. aquiferous parenchyma; sg. sclerenchymatic girders; cc. concertini cells; ch. chlorenchyma; cvb. collateral vascular bundle. Scale bars: A, D = 100 μm; B, E—10 μm; C, F—5 μm.