Nota científica / Scientific note Dyckia tubifilamentosa ( Pitcairnioideae-Bromeliaceae ) : a new species from Northeastern Brazil

(Dyckia tubifilamentosa (Pitcairnioideae-Bromeliaceae): a new species from Northeastern Brazil). Dyckia tubifilamentosa Wand. & G. Sousa is described and illustrated. It differs from the other species of the genus Dyckia by several distinctive characters, namely: the ovoid shape of the flower buds, the long and exserted staminal tube formed from completely connate white filaments, the anther initially connivent and then divergent, along with the fruit with partially persistent perianth. Dyckia tubifilamentosa is found in some areas of the semiarid region of Northeastern Brazil (Piauí State), growing in the Caatinga and transitional Caatinga-Cerrado biomes.

Bromeliaceae comprises 43 genera and 1290 species in Brazil (Forzza et al. 2014), which represents almost 40% of the family's diversity.This family is found in all Brazilian ecosystems and is very common in the humid coastal forest region (Atlantic Forest) and in the Cerrado vegetation, especially on rocky outcrops.
Very recently, terrestrial and rupicolous specimens of a taxon distinct from the previously described species of Dyckia were collected in the State of Piauí and are described herewith as a new species.The flower buds are greenish and ovoid, having a long exserted staminal tube, most of the ovary's length is above the petals and sepals; the fruits are capsular with winged seeds.Dyckia tubifilamentosa is easily distinguished from the other species of Dyckia by the ovoid shape of the flower buds, a long and exserted staminal tube formed from completely connate filaments which become vinaceous to purplish at post-anthesis; anthers are initially connivent and then divergent and the perianth is partially persistent in the fruit.This combination of characters is a distinctive and unusual set of diagnostic characters within the genus.
Etymology: The epithet refers to the long staminal tube.
Habitat: Heliophilous plants growing on rocky soils or on rock outcrops in the Caatinga vegetation (figure 2  Dyckia tubifilamentosa can be ascribed to the Pitcairnioideae subfamily by the terrestrial or rupicolous habit (figures 2 a-c), leaves with spiny margins (figure 1 a) and capsular fruits with winged seeds (figures 1 m, n) which are common features in most genera of the subfamily.The characteristics are the same as those used in the circumscription of Pitcairnioideae, both in the wide sense (Smith & Downs 1974) or under the new concept (Pitcairnioideae s. str.) adopted by Givnish et al. (2011).
This new species has lateral inflorescences (figures 1 a, 2 c), a common character in most species of Dyckia.However, it differs from the other species of the genus by many distinctive characters, namely: the ovoid flower buds (figures 1 f, 2 d), the long exserted staminal tube formed by completely connate white filaments which become vinaceous to purplish after the anthesis (figures 1 a, g, 2 e-g), the initially connivent then divergent and persistent anthers (figures 1 g, h, 2 e-g) and the fruit with partially persistent perianth and gynoecium.These combined features are good and unusual diagnostic characters in the genus.
Dyckia usually presents either orange or red to yellow petal with stamens adnate to the petals or to the sepals forming a common ring, erect and narrow to compact stigma lobes (Forzza & Wanderley 1998, Forzza 2005).The staminal tube in Dyckia is often short, and when longer it never exceeds the corolla (Smith & Downs 1974).Dyckia tubifilamentosa also has oblong-lanceolate petals, whereas often in Dyckia they are ovate to obovate.These characters, observed in the new species, are considered part of the morphological character variation of Dyckia, thus widening the morphological circumscription of the genus.
Dyckia is morphologically related to Encholirium, especially because both genera share the presence of naked petals.They can usually be distinguished by the lateral inflorescences and adnate filaments in Dyckia, while Encholirium often has a terminal inflorescence and free filaments.The weak delimitation between these two genera can be seen in certain intermediate species of each genus which show overlapping characters.Dyckia tubifilamentosa resembles Encholirium in its elongate and spirally conduplicate stigma lobes and green sepals and petals, however, the new species is easily distinguished from all species of Encholirium by its lateral scape and staminal tube, absent in Encholirium and present in almost all species of Dyckia.Smith & Downs (1974) characterized the genera of the Pitcairnioideae s.l. by the position of the ovary, as for example, by an entirely superior ovary (Encholirium) or a partially or entirely inferior one (Dyckia).However, ovary position is not as consistent as previously assumed within the genera of Pitcairnioideae.Bernardello et al. (1991) and  Forzza (2005) reported perigynous flowers with a short epigynous tube in Encholirium.In Dyckia tubifilamentosa, the occurrence of perigynous flowers was not confirmed, but an inconspicuous tube can be seen (figure 1 k).The capsular fruit (figure 1 m) and the appendaged seeds (figure 1 n) found in D. tubifilamentosa are also described within the Pitcairnioideae both in the wide or strict senses (Smith & Downs 1974, Givnish et al. 2011).
The distinctive and unusual combination of characters in Dyckia tubifilamentosa led us initially to consider proposing a new genus.Therefore, considering the weak delimitation of related genera of Pitcairnioideae s.l., emphasized by Krapp et al. (2014), we have decided to describe this new species under Dyckia, with which it shares some diagnostic characters (lateral inflorescence and connate filaments) and similar pollen morphology, with monosulcate pollen and reticulate exine (figures 2 h, i).

Figure. 1 .
Figure. 1. Dyckia tubifilamentosa Wand.& G. Sousa (from the holotype).a. Habit.b.Detail of the base of the peduncle.c.Floral bract.d.Sepals.e. Petals.f.Floral bud.g.Flower with the long staminal tube.h.Anthers at pre-anthesis.i. Detail of the gynoecium with the staminal tube longitudinally sectioned.j.Spirally conduplicate stigma.k.Longitudinal section of the base of the flower with a detail of the vestigial tube and the superior ovary.l.Transversal section of the ovary.m.Fruit.n.Seed.

Figure 2 .
Figure 2. Dyckia tubifilamentosa Wand.& G. Sousa (from the holotype).a.General view of the area of occurrence in Piauí State, Northeastern Brazil.b.Habit.c. Detail of the rosette with a lateral peduncle.d.Immature inflorescence with yellowish flower buds.e. Inflorescence showing buds and open flowers with a whitish and long staminal tube and divergent anthers.f.Inflorescence with flowers with whitish and long staminal tube and flowers with reddish tube at post-anthesis.g.Inflorescence showing secund flowers.h-i .Pollen grains (Sousa et al. 713).h.Equatorial view showing the monosulcate aperture.i. Polar view, detail of the reticulate exine.(scales bar: h = 10 µm; i = 5 µm).
a) as well as in areas considered transitional to the Cerrado biome in the State of Piauí, Northeastern Brazil.