Siderasis zorzanellii M.Pell. & Faden, 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 : 28-31

6. Siderasis zorzanellii M.Pell. & Faden sp. nov. Figs 1A , 2 , 3B-C , 12

Diagnosis.

Similar to S. spectabilis due to its vining habit, distichously-alternate leaves, blades asymmetric at base, main florescence a many-branched thyrse, with alternate cincinni, flowers bisexual or staminate, zygomorphic, stamens unequal, curved upwards and sigmoid filaments. It can be differentiated from by its chartaceous and sparsely velutine leaves, inflorescences axillary in the primary branches or terminal in the secondary branches, and petals white with glabrous margins.

Type.

Brazil. Espírito Santo: Iúna, Serra do Valentim , ao lado do transecto 1, 20.4989°S, 41.4725°W, fl., 27 Mar 2014, J.P.F. Zorzanelli 969 (holotype: RB!; isotype: VIES!) .

Description.

Vines ca. 0.5-3 m tall, terrestrial. Roots thin, fibrous, terminal tubers present, fusiform. Rhizomes buried deep in the ground. Subterraneous stems inconspicuous. Aerial stems twining, primary stem indefinite, densely branched, internodes elongate, 4.3-10.6 cm long, green, minutely velutine on both sides, hairs hyaline to light brown; secondary branches definite, unbranched, (6.4-8-)15-34 cm long, internodes elongate, 2-2.3 cm long, green, minutely velutine on both sides, hairs hyaline to light brown. Leaves distichously-alternate, evenly distributed along the secondary branches, sessile; sheaths 2-2.7 cm long, green to brown, minutely velutine, with a line of eglandular hairs opposite the leaf above, margins setose to densely setose, hairs hyaline to light brown; subpetiole 2.9-3.5 mm long to inconspicuous, C-shaped in section, canaliculate, membranous, green to dark green, minutely velutine on both sides, hairs hyaline to light brown; blades 5.1-12.7 × 1.1-2.8 cm, linear elliptic to linear lanceolate, chartaceous, adaxially dark green to green, becoming dark brown when dry, abaxially light green to green, becoming greyish green to olive-green when dry, sparsely minutely velutine on both sides, hairs hyaline to light brown, base slightly asymmetric to asymmetric, cuneate to narrowly rounded, margins green to vinaceous, flat, glabrous, apex acuminate to caudate, straight; midvein conspicuous, impressed adaxially, prominent, obtuse abaxially, secondary veins 2-3 pairs, inconspicuous on both sides, becoming more evident when dry. Synflorescence composed of a solitary main florescence. Main florescence (inflorescence) a pedunculate, many-branched thyrse, with alternate cincinni, axillary in the primary branches or terminal in the secondary branches; basal bract reduced, rarely leaf-like, sessile, 1.7-2 × 0.2-0.4 cm, green, minutely velutine on both sides, base opaque, margins minutely velutine, apex caudate, hairs hyaline; peduncle 0.9-1.2 cm long, light green to green, minutely velutine hairs hyaline; cincinni bract linear triangular, 3-15.3 × 1.4-1.8 mm, green to brown, minutely velutine on both sides, base truncate, margin velutine, setose only at base, apex acuminate to caudate, hairs hyaline; cincinni 14-19 per thyrse, (1-)2-5-flowered, peduncles 1.2-5.3 mm long, white to pink, minutely velutine, hairs hyaline, erect in fruit; bracteoles ovate to broadly ovate, flat, 1-1.7 × 0.8-1.3 mm, vinaceous to brown, minutely velutine, base rounded, margin hyaline, ciliate, apex hyaline, acute to obtuse, hairs hyaline. Flowers bisexual or staminate, zygomorphic, 0.7-0.9 cm diameter, pedicellate; pedicel 1.2-2.8 mm long, white, minutely velutine, hairs hyaline, patent and slightly elongate in fruit; floral buds 3.6-4.9 × 2.2-4.1 mm, broadly obovoid to subglobose, white, apex truncate to rounded, green; sepals 3.6-4 × 1.5-2.1 mm, narrowly ovate to elliptic, cymbiform, unequal, the uppermost external, broader and shorter than the others, fleshy, white, externally minutely velutine, hairs hyaline, internally glabrous, margin hyaline, glabrous to sparsely velutine, hairs hyaline, apex obtuse, green; petals 3.7-4.5 × 2.7-3.4 mm, trullate to obovate, the lowermost narrower than the others, white, base cuneate, margin entire, glabrous, apex obtuse to rounded; stamens 6, unequal, the anterior longer than the posterior, curved upwards, filaments 1.3-4.2 mm long, sigmoid, white, anthers 0.7-0.9 × 0.7-1 mm, anther sacs white, connectives quadrangular in the shorter stamens and rectangular in the longer, white; ovary 1.5-1.7 × 1.1-1.2 mm, ellipsoid, white, velutine, hairs hyaline, style 2.7-3.2 mm long, curved upward at the apex, white; stigma annular-capitate, papillate, white. Capsules 0.9-1.3 × 0.8-1.2 cm, subglobose to globose, green, sparsely reticulate, sparsely velutine, hairs hyaline. Seeds 3.6-3.9 × 2.9-3.2 mm, obconic to ellipsoid, medium to dark brown, testa scrobiculate; hilum longer than ½ the length of the seed; embryotega semidorsal; aril cream-colored, slightly translucent, thick.

Specimens seen (paratypes).

BRAZIL. Espírito Santo: Iúna, Serra do Valentim, trilha do Sr. Aristides, próximo à borda da mata, fl., 27 Jan 2012, J.P.F. Zorzanelli et al. 328 (VIES); floresta do Sr. Aristides, próximo à borda da vegetação, antes da primeira subida íngreme da trilha, fl., 15 Dec 2015, J.P.F. Zorzanelli 1391 (RB, VIES); floresta do Sr. Aristides, próximo ao início do zigue-zague da trilha, 20°21' 56" S 41°28' 26" W, fr., 31 Mar 2016, J.P.F. Zorzanelli 1505 (RB, VIES).

Etymology.

The epithet honors the collector of the type specimens, João Paulo Fernandes Zorzanelli, Brazilian botanist and dear friend of the authors. JPFZ is an active and prominent collector in the state of Espírito Santo, with collections currently focused on Serra do Valentim, the type locality of S. zorzanellii .

Distribution and habitat.

Siderasis zorzanellii is confined to the municipality of Iúna, Espírito Santo (Fig. 2 ). It occurs in the "Floresta Ombrófila Densa Montana" vegetation, at 1200-1350 m above the sea level, generally near disturbed sites, being less frequent in well-preserved areas. This could be related to its climbing habit and the need of more sunlight exposure then the rosette species of the genus. This pattern is common in other liana and vine groups, such as Bignoniaceae , Malpighiaceae , and Sapindaceae ( Acevedo-Rodríguez, pers. comm.), especially evident in big families such as Asteraceae , where the primarily climbing genus Mikania Willd. is almost exclusively found at the edge of forests, along trails, and in disturbed areas (Oliveira 2015).

Phenology.

It was found in bloom from December to March and in fruit in March.

Conservation status.

Siderasis zorzanellii is very narrowly distributed, with an EOO of ca. 7.779 km2 and an AOO of ca. 300 km2. The subpopulations are small, with no more than 10 mature individuals each. Unlike for the rosette species in the genus, it is still uncertain if the two climbing species reproduce vegetatively through cloning. Flowering seems to be frequent, although fruits have been collected only once. Thus, following the recommendations from IUCN (2001), S. zorzanellii should be considered Critically Endangered [CR, A2abde+B1ab(iii, iv, v)+ B2ab(iii, iv, v)+C2a(ii)+D1+D2].

Affinities.

Siderasis zorzanellii is morphologically similar to S. spectabilis. Nevertheless, both species can be differentiated based on consistency of the leaf blades (chartaceous in S. zorzanellii vs. membranous in S. spectabilis ), density of their pubescence (sparsely minutely velutine vs. minutely velutine), position of the inflorescences (terminal in the secondary branches or axillary in the older nodes of the primary branches vs. exclusively terminal in the primary branches), floral morphology (flowers 0.7-0.9 cm diameter, petals white, margins glabrous vs. flowers 1-1.3 cm diameter, petals dark mauve to vinaceous, rarely light pink or white, margins ciliate with non-moniliform hairs), and by their disjunct distribution (southern montane Espírito Santo state vs. northern montane Rio de Janeiro state).

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 3. Growth forms in Dichorisandrinae s. s. A-D Siderasis Raf. emend. M. Pell. & Faden: A rosette habit of S. fuscata (Lodd.) H. E. Moore B rosette habit with flagelliform-shoots of S. albofasciata M. Pell. C habit of an immature, still prostrate, individual of S. zorzanellii M. Pell. & Faden. D habit of a mature individual of S. zorzanellii spirally ascending a tree. E-F Dichorisandra hexandra (Aubl.) C. B. Clarke: E intertwined habit F decumbent stem apex, bearing flowers and fruits. Photographs A-B, E-F by M. O. O. Pellegrini, C-D by J. P. F. Zorzanelli.

Figure 12. Siderasis zorzanellii M. Pell. & Faden. A habit, showing an immature individual B habit, showing a mature individual spirally ascending a tree C detail of a secondary branch, showing distichously-alternate, asymmetric leaves D detail of an axillary inflorescence, in the primary branch E detail of a terminal inflorescence, at pre-anthesis, in a secondary branch F detail of a terminal inflorescence, at anthesis, in a secondary branch, showing an open male flower G side view of a male flower, showing the unequal and sigmoid stamens H side view of a post-anthesis bisexual flower, showing the bent style I detail of the inflorescence bearing two mature capsules J dorsal and ventral view of the seeds, showing the rugose testa, cleft towards the semidorsal embryotega, and the C-shaped hilum. Photographs by J. P. F. Zorzanelli.