Siderasis medusoides M.Pell. & Faden, 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: 22-25

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Siderasis medusoides M.Pell. & Faden

sp. nov.

4. Siderasis medusoides M.Pell. & Faden   sp. nov. Figs 2 View Figure 2 , 9 View Figure 9


Similar to S. almeidae   due to its sessile to subpetiolate, entirely green leaves, present bracteoles, sessile flowers, purple filaments and style combined with white anthers, and oblongoid to broadly oblongoid capsules. Siderasis medusoides   is distinct due to its membranous leaves, elongate and tangled cincinni, small flowers, and purple to dark blue and elliptic to narrowly obovate or spatulate petals.


BRAZIL. Espírito Santo: Marilândia, perímetro urbano, na Estrada para Sao Pedro , fragment de floresta junto a uma serraria de madeira, a ca. 100 m do portão da serraria, em encosta de morro, 19°24'30.5"S 40°32'1.8"W, fl., fr., 20 Jan 2011, P. Fiaschi et al. 3489 (holotype: SPF barcode SPF200900!; isotype: MBML barcode MBML42135!) GoogleMaps   .


Herbs ca. 5-10 cm tall, rhizomatous, terrestrial. Roots with terminal tubers present. Rhizomes shallowly buried in the ground. Subterraneous stems short to inconspicuous, unbranched, dark green to vinaceous to brown, sparsely lanate, hairs light brown to hyaline. Aerial stems short to inconspicuous, unbranched; internodes inconspicuous to weakly elongate, green, lanate, hairs light brown to hyaline; flagelliform-shoots (ramets) absent. Leaves spirally-alternate, forming a rosette; sheaths 0.8-1.4 cm long, hispid, hairs hyaline to light brown; subpetiole 0.4-4.6 cm long to inconspicuous, D-shaped in cross section, canaliculate, dark green to vinaceous, hispid, hairs light brown to hyaline; blades 10-24.4 × 5.9-11.2 cm, elliptic to broadly elliptic, membranous, adaxially dark green, hispid, hairs light brown to hyaline, abaxially green to vinaceous, hispid to lanate, hairs light brown to hyaline, base cuneate, margins green, revolute, lanate, hairs light brown to hyaline, apex obtuse, rarely acute, straight; midvein conspicuous, adaxially impressed, abaxially prominent, acute, secondary veins 2-7 pairs, inconspicuous on both sides, becoming more conspicuous on both sides when dry. Synflorescence composed of a solitary main florescence, or with 1-15 coflorescences. Main florescence (inflorescence) reduced to a solitary pedunculate cincinnus; basal bract 7.6-10.4 × 4.6-6.2 cm, broadly elliptic to broadly ovate, slightly cymbiform, amplexicaulous, green, sparsely hispid, hairs rusty, opaque at the base and margins; inflorescence main axis 2.3-4.8 cm long, green, densely hispid, hairs rusty; cincinni bract ovate, amplexicaulous, 2.4-4.9 × 1.5-4 mm, green, hispid, hairs rusty, apex acute; cincinni (5-)8-26-flowered, peduncles 5.6-12.7 mm long, green, densely hispid, hairs rusty, reflexed in fruit; bracteoles 0.9-1.5 × 0.8-1.3 mm, broadly triangular, sessile, flat, green, hispid, hairs rusty, apex obtuse. Flowers bisexual, actinomorphic, 0.9-1.2 cm diameter, sessile; pedicel inconspicuous, elongate in fruit, 1-2.2 mm long, green, hispid, hairs light brown to rusty; floral buds 2.6-5.4 × 2-3.7 mm, broadly ellipsoid to broadly obovoid, light green, apex obtuse to truncate; sepals 3.7-6.7 × 2.2-3.6 mm, elliptic to obovate, the uppermost external and broader than the others, membranous, externally light green to green, sparsely hispid, hairs light brown to rusty, internally light green, purple towards the apex, glabrous, margin hyaline, apex obtuse; petals 4.4-10.1 × 1.9-6.7 mm, elliptic to narrowly obovate to spatulate, the lowermost usually broader than the others, bluish purple to dark blue, margin entire to irregularly lacerated, apex obtuse to round, irregularly lacerated; stamens 6, equal, filaments 2.6-3.4 mm long, bluish purple to dark purple, anthers 0.8-1 × 1-1.3 mm, anther sacs semicircular, divergent, white, connectives quadrangular, white; ovary broadly oblongoid, 1.2-1.9 × 1-1.5 mm, white, densely hispid, hairs white; style 1.3-4.7 mm long, straight, bluish purple to dark blue, lilac at the terminal end; stigma annular-truncate, lilac to white, papillate. Capsules 6.8-9.4 × 6.7-7.8 mm, oblongoid to broadly oblongoid, smooth, green, hispid, hairs rusty. Seeds 3.6-4.1 × 2.6-3.2 mm, obconic to ellipsoid, medium to dark brown, testa rugose; hilum longer than ½ the length of the seed; embryotega semilateral; aril cream-colored, slightly translucent, thick.

Specimens seen (paratypes).

BRAZIL. Espírito Santo: Marilândia, rodovia Marilândia-Rio Bananal, ca. 1 km N de Marilândia, remanescente de floresta junto a Cerâmica Floresta, fl., 6 Dec 1994, J.R. Pirani et al. 3421 (NY, SPF); Liberdade, propriedade de Deoclécio Lorenccini, 19°21' 7" S 40°30' 51" W, fl., fr., 22 Mar 2007, V. Demuner et al. 3429 (HERB, MBML); propriedade de Sônia e Reinaldo Bautz, 19°20' 8" S 40°32' 8" W, fl., 10 Dec 2007, V. Demuner et al. 4682 (MBML). Santa Leopoldina, Colina Verde (Morro do Agudo), propriedade de Israel Elias Ramos, trilha da casa, 20°6' 12" S 40°26' 34" W, fl fr., 13 Mar 2007, V. Demuner et al. 3118 (MBML).


The epithet alludes to the extremely elongated cincinni, common in mature individuals of this species, due to their resemblance to the snakes that composed the hair of Medusa, one of the three Gorgon sisters from Greek mythology.

Distribution and habitat.

Siderasis medusoides   is known from the municipalities of Marilândia and Santa Leopoldina, in the state of Espírito Santo (Fig. 2 View Figure 2 ). It grows in lowland Atlantic Forest, in shady and moist areas with great leaf litter accumulation, 90-550 m above the sea level.


It blooms from December to March and fruits between January and March.

Conservation status.

Siderasis medusoides   possesses narrow EOO (ca. 11037 km2) and AOO (ca. 2000 km2), and based solely on distribution data should be treated as Endangered (EN). Nonetheless, it is known from only five collections in three different localities. They were made within urban areas, and these localities have suffered greatly with direct anthropic influence and deforestation in recent years. We have made several attempts to recollect S. medusoides   , but they were all unsuccessful. Thus, we suggest that S. medusoides   be considered Critically Endangered [CR, A2abcd+B2ab(i, ii, iii, iv)+C1+C2b+D2].


Siderasis medusoides   is similar to S. almeidae   and S. albofasciata   , due to their sessile to subpetiolate leaves, inflorescence with elongate main axis, bracteolate cincinni, sessile flowers, and purple filaments and style combined with white anthers. Nevertheless, it can be easily differentiated from S. almeidae   by its inconspicuous subterraneous and aerial stems (vs. subterraneous stems absent and aerial stems elongate, in S. almeidae   ), membranous leaves appressed against the soil (vs. succulent and ascending), membranous and internally light green sepals (vs. fleshy and internally lilac to purple), narrowly obovate to spatulate petals (vs. rhomboid to broadly obtrullate), and hispid ovary (vs. lanate). It can be differentiated from S. albofasciata   by lacking flagelliform-shoots (vs. flagelliform-shoots produced after the fertile period, in S. albofasciata   ), concolorous and membranous leaves (vs. adaxially variegated, abaxially vinaceous, succulent leaves), petals entirely purple to bluish purple (vs. petals with white basal third), and white anthers (vs. anthers purple to bluish purple). Siderasis medusoides   is peculiar due to its membranous leaves appressed to the soil, tangled and elongate cincinni, small flowers, and narrow petals.