Siderasis albofasciata M.Pell., Nordic J. Bot. 35(1): 30. 2017.

Pellegrini, Marco O. O. & Faden, Robert B., 2017, Recircumscription and taxonomic revision of Siderasis, with comments on the systematics of subtribe Dichorisandrinae (Commelinaceae), PhytoKeys 83, pp. 1-41 : 14-15

1. Siderasis albofasciata M.Pell., Nordic J. Bot. 35(1): 30. 2017. Figs 1B , 2 , 6

Type.

BRAZIL. Espírito Santo: Santa Teresa, Alto do Julião, Fazenda Novo Triunfo , property of Mrs. Florinda, gallery forest with rocky formations, above the dam, fl., fr., 18 Apr 2013, M.O.O. Pellegrini et al. 337 (holotype: RB barcode RB00813532!; isotype: US!).

Description.

Herbs ca. 10 cm tall, rhizomatous, terrestrial or rupicolous. Roots with terminal tubers present. Rhizomes buried deep in the ground. Subterraneous stems with internodes moderately elongate, vinaceous, sparsely lanate, hairs light brown to hyaline. Aerial stems short to inconspicuous, unbranched; internodes inconspicuous to weakly elongate, vinaceous, lanate, hairs light brown to hyaline; flagelliform-shoots (ramets) present. Leaves spirally-alternate, forming a rosette at the apex of the aerial stems, sessile to subpetiolate; sheaths 0.7-1.3 cm long, vinaceous, with or without green spots, lanate, hairs light brown to rusty; subpetiole 1-2.7 cm long to inconspicuous, D-shaped in cross section, canaliculate, dark green to vinaceous, hispid, hairs light brown to hyaline; blade (4.5-4.8-)10-15.8 × (3.1-3.5-)4.4-7.2 cm, elliptic to obovate, rarely lanceolate, succulent, adaxially dark green, with a thin white stripe along the midvein, hispid, hairs light brown to hyaline, abaxially vinaceous to atro-vinaceous, lanate, hairs light brown, base slightly subcordate to cuneate, vinaceous, margins vinaceous, slightly revolute, apex acute, straight to curved downwards; midvein adaxially inconspicuous, slightly impressed, abaxially prominent, obtuse, secondary veins 3-5, inconspicuous in both faces, becoming more evident when dry. Synflorescence composed of a solitary main florescence with 1-2 coflorescences. Main florescence (inflorescence) reduced to a solitary pedunculate cincinnus, terminal or apparently so; basal bract 11.3-13.4 × 4.8-7.8 mm, triangular, slightly cymbiform, amplexicaulous, vinaceous, hispid, hairs rusty, opaque at the base and margins; inflorescence main axis 2.1-4.4 cm long, vinaceous, densely hispid, hairs rusty to brown; cincinni bract 3.3-6 × 2.2-4.6 mm, triangular, amplexicaulous, vinaceous, hispid, hairs rusty; cincinni (3-)5-8-flowered, peduncles 0.8-1.6 cm long, vinaceous, densely hispid, hairs rusty to brown, reflexed in fruit; bracteoles 2.9-4.4 × 2.8-3.2 mm, broadly ovate to depressed ovate, sessile, revolute, vinaceous to pinkish purple, sparsely hispid, hairs rusty, apex rounded to truncate. Flowers bisexual, actinomorphic, 2.3-2.8 cm diameter, pedicellate; pedicel 1-7.2 mm long, white to light green, hispid, hairs rusty, reflexed and slightly elongate in fruit; floral buds 0.7-1.6 × 0.3-0.6 cm, ellipsoid to narrowly obovoid, light green, apex obtuse; sepals 0.9-1.1 × 0.4-0.7 cm, narrowly ovate to elliptic, membranous, white to light green on both sides, externally sparsely hispid, hairs hyaline to rusty, rusty in fruit, internally glabrous, margin hyaline, apex obtuse, slightly purple; petals 1.3-1.6 × 1-1.2 cm, broadly ovate to broadly elliptic, bluish lilac to bluish purple, proximal third white, base cuneate, margin entire, apex obtuse to rounded, sometimes irregularly lacerated; stamens equal, filaments 5-7.1 mm long, straight, white, terminal third purple to bluish purple, anthers 1.5-2.2 × 1.3-2 mm, anther sacs purple to bluish purple, connectives quadrangular, purple; ovary 1.5-2 × 1.5-2 mm, globose, white, densely hispid, hairs hyaline, style 4.1-6.3 mm long, straight, white, terminal third purple to bluish purple; stigma annular-truncate, purple to bluish purple, papillate. Capsules 1-1.3 × 0.7-0.9 cm, subglobose to broadly oblongoid in outline, smooth, green, when mature light brown, hispid, hairs rusty. Seeds 3.3-5.2 × 2.4-2.9 mm, obconic to ellipsoid, medium to dark brown, testa rugose; hilum approximately ½ the length of the seed; embryotega semilateral; aril cream-colored, slightly translucent, thick.

Specimens seen

. BRAZIL. Espírito Santo: Fundão, Alto Piaba, cultivado na casa de epífitas do MBML, fl., 13 Sep 1989, W. Boone 1349 (MBML); A.P.A. do Goiapaba-açú, Piabas, propriedade de Albino Casimiro, fl., 8 Nov 2007, A.P. Fontana & K.A. Brahim 2827 (MBML, RB). Santa Teresa, Alto do Julião, propriedade de João Luiz Rodrigues de Souza, fl., 23 Feb 2007, A.P. Fontana & K.A. Brahim 2975 (MBML, RB); Cabeceira do 25 de Julho, Julião, fl., 10 Nov 2007, L. Kollmann et al. 11839 (MBML).

Etymology.

The epithet means “white-striped”, making reference to the thin and always present, white to silver stripe along the midvein of this species’ leaves.

Distribution and habitat.

Siderasis albofasciata is known exclusively from the municipalities of Santa Teresa and Fundão, state of Espírito Santo (Fig. 2 ). It occurs in the understory of evergreen forests, in shady areas with shallow and rocky soil, with great leaf-litter accumulation.

Phenology.

It blooms from November to February. This species was collected in fruit in April, when mature and immature capsules were seen.

Conservation status.

According to Pellegrini (2017), S. albofasciata should be considered as Critically Endangered [CR, B1ac(ii, iii, iv)+B2ab(ii, iii, iv)+C2a(i)].

Affinities.

Siderasis albofasciata is similar to S. fuscata due to its leaves being of a different color along the midvein of the adaxial side, abaxially vinaceous, and inflorescences covered with rusty hairs. However, S. albofasciata can be readily differentiated by its sessile to subpetiolate leaves covered by hyaline to light brown indumentum (vs. petiolate leaves with bright red to red indumentum, in S. fuscata ), a well-defined white stripe along the midvein on the adaxial side of the blade (vs. sometimes blotched silver to metallic light green), main axis of the synflorescence elongate (vs. inconspicuous), bracteoles present (vs. bracteoles absent), cincinni (3-)5-8-flowered [vs. 1-3(-4)-flowered], anthers purple, filaments and style apically purple (vs. androecium and gynoecium completely white), testa brown and rugose (vs. grey to light grey and foveolate), and aril cream-colored, thick and slightly hyaline (vs. aril colorless and inconspicuous). It is also similar to S. almeidae and S. medusoides due to the leaf blades adaxially hispid, abaxially lanate, and presence of bracteoles in the cincinni. Siderasis albofasciata can be easily differentiated from all the accepted species in the genus by the peculiar coloration pattern in its androecium and gynoecium.

Furthermore, S. albofasciata produces unique axillary flagelliform-shoots after its flowering period. Each flagelliform-shoot is homologous to a daughter ramet, consisting of an extremely elongate stem, that may or not develop leaf blades (sometimes the blades are very reduced or absent), and a terminal rosette that roots after it touches the soil. This clonal propagation strategy gives this species a chandelier appearance, similar to many epiphytic bromeliads. This clonal propagation strategy is unique within subtribe Dichorisandrinae ( Pellegrini 2017).

Figures

Figure 1. Floral morphology of subtribe Dichorisandrinae s. l. A-C Siderasis Raf. emend M. Pell. & Faden: A S. fuscata (Lodd.) H. E. Moore B S. albofasciata M. Pell. C S. zorzanellii M. Pell. & Faden. D-L Dichorisandra J. C. Mikan: D D. acaulis Cogn. E D. hexandra (Aubl.) C. B. Clarke F D. thyrsiflora J. C. Mikan G D. paranaensis D. Maia et al. H D. nana Aona & M. C. E. Amaral I D. incurva Mart. J D. penduliflora Kunth K D. sagittata Aona & M. C. E. Amaral L D. radicalis Nees & Mart. M Cochliostema odoratissimum Lem. N Geogenanthus rhizanthus (Ule) G. Brueckn. O Plowmanianthus panamensis Faden & C. R. Hardy. Photographs A-B, D-G, J by M. O. O. Pellegrini, C by J. P. F. Zorzanelli, H by V. Bittrich, I by G. H. Shimizu, K by J. L. Costa-Lima, L by M. A. N. Coelho, M by R. Moran, N by D. Scherberich, and O by C. R. Hardy.

Figure 2. Distribution map of Siderasis Raf. emend. M. Pell. & Faden. Blue circles - S. albofasciata; Blue triangles - S. almeidae; Red circles - S. fuscata; Red triangles - S. medusoides; Blue square - S. spectabilis; Red Square - S. zorzanellii; BA - state of Bahia; ES - estate of Espirito Santo; RJ - estate of Rio de Janeiro.

Figure 6. Siderasis albofasciata M. Pell. A habit, showing the well-defined white stripe along the midvein of the leaves and the flagelliform-shoots with terminal rosettes B detail of the abaxial side of the leaf, showing the light-brown lanate indumentum C detail of the adaxial side of the leaf, showing the light-brown hispid indumentum D detail of the inflorescence, showing the solitary cincinnus E flower F detail of the androecium and the gynoecium G detail of the capsules, the left one immature with evident accrescent sepals and the right one mature H detail of an open capsule, showing the biseriate to partially uniseriate, arillate seeds I dorsal view of a seed, showing the semi-lateral embryotega and the cream-colored, slightly translucent and thick aril. Photograph F by L. Kollmann, remaining by M. O. O. Pellegrini.