Tradescantia seubertiana M.Pell., Phytotaxa 265(1): 80. 2016.

Pellegrini, Marco O. O., 2018, Wandering throughout South America: Taxonomic revision of Tradescantia subg. Austrotradescantia (D. R. Hunt) M. Pell. (Commelinaceae), PhytoKeys 101, pp. 1-97 : 36-40

10. Tradescantia seubertiana M.Pell., Phytotaxa 265(1): 80. 2016. Figs 26 , 27

Holotype.

BRAZIL. Santa Catarina: Grão Pará, Serra do Corvo Branco, 4 Oct 2014, fl., M.O.O. Pellegrini et al. 436 (RB barcode RB01045343!; isotypes: UEC!, US barcode US01926164!).

Description.

Herbs rupicolous, ca. 20-40 cm tall. Stem erect, succulent, little branched, branching at the base, rarely branching at the upper half; internodes 3.1-6.3 cm long at base, distally shorter, green to reddish-purple to vinaceous, glaucous, glabrous. Leaves distichously-alternate, sessile; ptyxis convolute; sheaths 0.4-1.3 cm long, green to green with vinaceous striations to vinaceous, glaucous, glabrous, margin glabrous; blades ovate to broadly ovate, 2.8-7.7 × 0.9-3.2 cm, falcate to complicate, succulent, glabrous, adaxially light-green, glaucous, abaxially slightly lighter to reddish-purple to vinaceous, glaucous, turning olive-green to light-brown when dry, base cordate to slightly amplexicaulous to obtuse, rarely cuneate, margin green, glabrous, slightly revolute, apex acute; midvein conspicuous to inconspicuous, adaxially impressed to inconspicuous, secondary veins inconspicuous on both sides, becoming more evident on both sides when dry. Inflorescences terminal or axillar in the distal portion of the stems, 1 per leaf axis; peduncles 1.6-3.7 cm long, green to reddish-purple to vinaceous, glaucous, glabrous; cincinni bracts unequal to strongly unequal to each other, ovate to broadly ovate, 0.7-3.3 × 0.4-1.2 cm, leaf-like, glabrous, adaxially light-green, glaucous, abaxially slightly lighter to reddish-purple to vinaceous, glaucous, base cordate to obtuse, not saccate, margin glabrous, slightly revolute, apex acute; double cincinni ca. 6-14-flowered. Flowers 0.8-1 cm diam., pedicels 0.7-1.4 cm long, green to reddish-purple to vinaceous, glaucous, glabrous, rarely with some odd glandular hairs; floral buds ellipsoid; sepals 4.8-5.9 × 2.4-4.6 mm, dorsally keeled, green to reddish-purple to vinaceous, glaucous, glabrous; petals 6.3-7 × 3.2-4.4 mm, light-pink to pink; filaments 2.8-3.2 mm long, anthers 0.5-0.8 × 1.3-1.5 mm; ovary 1-1.3 × 0.9-1.2 cm, style 4.3-8.5 cm long; pistil longer than the stamens. Capsule 1.8-2.6 × 1.8-2.2 cm. Seeds 1-1.2 × 0.8-1 mm, testa grey to greyish-brown, costate, cleft towards the embryotega; hilum longer than ½ the length of the seed.

Specimens seen.

BRAZIL. Rio Grande do Sul: Bagé, km 82 da rodovia Caçapava do Sul/ Bagé, fl., fr., 30 Sep 1982, J. Mattos 25637 (HAS); Bento Gonçalves, Santa Teresa, fl., 20 Oct 1984, R.A. Wasum 511 (HUCS, PACA, US); na descida da Serra do Vale do Rio das Antas, fl., fr., 17 Oct 1988, N. Silveira & C.J. Mansan 6066 (HAS); Caxias do Sul, Galópolis, fl., 31 Oct 1949, A. Sehnem 4027 (CORD); Pelotas, Instituto Agronômico do Sul, fl., fr., Mar 1955, Boeira 1188 (HAS); Rio Pelotas, BR-116, km 270, fl., 23 Nov 1980, A. Krapovickas & R. Vanni 36870 (CORD, CTES); São Francisco de Paula, Barragem Passo do Inferno, fl., fr., 28 Nov 1996, C. Mansan & M. Neves s.n. (HAS 36560); fl., 27 Oct 1997, C. Mansan 65 (HAS); Santa Maria do Herval, fl., fr., 1 Nov 1989, N. Silveira 9272 (HAS); Vacaria, entre Vacaria e Caxias do Sul, fl., fr., 26 Oct 1961, E. Pereira et al. 6527 (R, RB); à 8km do Rio Pelotas, rodovia para Lajes, fl., fr., s.dat., J. Mattos & S.N. Mattos 24682 (HAS); fl., fr., 29 Nov 1986, J. Mattos & S.N. Mattos 30378 (HAS); BR-116, divisa com Lages, fl., 12 Dec 2015, M.O.O. Pellegrini & R.F. Almeida 481 (RB); Veranópolis, fl., 18 Oct 1986, G. Grazziotin 2149 (HPBR, HUCS, US); 10 km S de Veranópolis, fl., 16 Sep 1971, J.C. Lindeman & B. Irgang 8107 (CORD, CTES, EFC, HAS, ICN); Estação Experimental Fitotécnica, fl., fr., 4 Nov 1982, J. Mattos & S.M.H. Bassan 28557 (HAS); no vale do Rio das Antas, fl., 27 Sep 1985, J. Mattos & S.M.H. Bassan 28542 (HAS); no vale do Rio das Antas, fl., 27 Sep 1985, J. Mattos & S.N. Mattos s.n. (HAS no. 67967); no vale do Rio das Antas, na rodovia para Veranópolis, fl., fr., 27 Oct 1987, J. Mattos & S.N. Silveira 31228 (HAS). Santa Catarina: Urubici, Rio dos Bugres, fl., fr., 11 Nov 2001, G. Hatschbach et al. 72640 (MBM); Comunidade de São Pedro, fl., 15 Nov 2008, Silva et al. 7171 (MBM).

Distribution and habitat.

Tradescantia seubertiana is endemic to the alpine region of Rio Grande do Sul and Santa Catarina, Brazil; in the Atlantic Forest and Pampa domains (Fig. 27 ). It can be found growing on wet rock walls, from ca. 700 to 1.800 metres above sea level.

Phenology.

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

Etymology.

This species was named after the prominent German botanist Moritz August Seubert (1818-1878), in appreciation for his extensive contribution to Commelinaceae systematics, especially for his contributions to the knowledge of the Brazilian Commelinaceae .

Conservation status.

As stated by Pellegrini (2015), T. seubertiana is known from few localities and very small populations, none of which are inside any conservation unit. This species is directly threatened by habitat loss, since all known collections are found along roads and high roads, currently being enlarged. In the near future, most known subpopulations might become extinct. Thus, following the IUCN recommendations ( IUCN 2001), this species should be considered Critically Endangered [CR, A3cd+C2a(i)].

Comments.

Tradescantia seubertiana is a member of the well supported T. crassula group ( Pellegrini 2017). This group is characterised by Pellegrini (2017) as comprising species with erect habit, definite base, convolute ptyxis, complicate to falcate and succulent leaves, generally with inconspicuous secondary veins (Fig. 26B-D ), cincinni bracts non-saccate (Fig. 26E-G ), pistil longer than the stamens (Fig. 26G-H ), seeds cleft towards the embryotega, hilum longer than ½ the length of the seed and for preferentially inhabiting open areas and rocky outcrops. Tradescantia seubertiana is morphologically similar to T. crassula and T. decora , but only superficially similar to T. cerinthoides , especially due to its pink petals (which can range in T. cerinthoides from white to light pink to pink to lilac; Fig. 10N ; Pellegrini 2015, 2017; Pellegrini et al. 2017). It can be differentiated from T. crassula and T. decora by its glabrous leaf-sheath margin - a very uncommon character in Commelinaceae - (vs. leaf-sheath margin ciliate in T. crassula and long ciliate in T. decora ), leaf base cordate to slightly amplexicaulous to obtuse (vs. obtuse to truncate), ellipsoid flower buds (vs. broadly ovoid in T. crassula and T. decora ), sepals glabrous (vs. setose along the keel in T. crassula and with minute caducous hairs at the apex of the sepals in T. decora ) and by its light pink to pink petals (vs. white in T. crassula ). It can be easily differentiated from T. cerinthoides by being almost entirely glabrous (vs. generally densely pubescent in T. cerinthoides with a mixture of glandular and eglandular, hyaline to light brown to golden hairs), inconspicuous secondary veins (vs. conspicuous in T. cerinthoides ), its unequal cincinni bracts (vs. equal in T. cerinthoides ), ellipsoid floral buds (vs. ovoid in T. cerinthoides ) and keeled and glabrous sepals (vs. not keeled and densely pubescent in T. cerinthoides with a mixture of glandular and eglandular, hyaline to light brown to golden hairs). Additionally, T. seubertiana is found growing exclusively on wet rocky cliffs, while T. cerinthoides , T. crassula and T. decora are commonly found growing in open fields, sand dunes near the shore, dry rocky outcrops or understorey as terrestrial or epiphytes.

Figures

Figure 10. Tradescantia cerinthoides Kunth. A rupicolous subpopulation in the municipality of Vacaria, state of Rio Grande do Sul, Brazil B-C habit B habit, showing the spirally-alternate leaves C habit, showing the distichously-alternate leaves D-F stems and leaf-sheaths D detail of a glabrous stem, vinaceous with green striations and sparsely hispid leaf-sheath, light green with vinaceous striations E detail of a hispid stem, vinaceous with green striations and hispid leaf-sheath, vinaceous with darker striations F detail of a velutine stem, medium green and velutine, pinkish leaf-sheath with vinaceous striations G-J pubescence of the leaf-blades G abaxial side, showing the dark vinaceous colouration and lack of pubescence H abaxial side, showing the vinaceous colouration and sparsely hispid indumentum I adaxial side, showing the medium green colouration and the hispid indumentum J abaxial side, showing the medium green colouration and velutine indumentum K inflorescence, showing the non-saccate cincinni bracts and velutine indumentum L-M floral buds L green floral bud, showing the velutine indumentum M vinaceous floral bud, showing the hispid indumentum N front view of flowers from the same subpopulation (Vacaria, Rio Grande do Sul, Brazil), showing the variation of sepal colour (green to dark vinaceous), sepal pubescence (velutine to sparsely hispid to hispid to densely hispid) and petal colour (white to shades of pink to lilac) O dorsal and ventral views of the seed, showing the costate testa cleft towards the embryotega and the hilum longer than 1 / 2 the length of the seed. Photos by M. O. O. Pellegrini.

Figure 26. Tradescantia seubertiana M. Pell. A Serra do Corvo Branco, Santa Catarina, Brazil B habit, showing the erect stem C detail of the stem, leaf-sheath and leaf, showing the amplexicaulous leaf-blade base D detail of the stem, leaf-sheath and the abaxial side of the leaf-blade, showing the reddish-purple colouration and the complete absence of indumentum E detail of the inflorescence, showing the not saccate and unequal cincinni bracts F detail of the floral buds and flowers at post-anthesis, showing the reddish-purple colouration of the pedicels and sepals and the complete absence of indumentum G side view of a flower, showing the green sepals and pink petals H front view of a flower, showing the pistil longer than the stamens. Photos by M. O. O. Pellegrini.

Figure 27. Distribution of Tradescantia seubertiana M. Pell. Yellow- Chaco and Pantanal; Olive-green- Pampa; Dark green- Atlantic Forest.