Discussion
In morphological terms, Canistrum alagoanum is very closely related to C. pickelii. Its recognition as a new species was only possible with the study of living specimens, since the samples available from herbaria did not provide all the information necessary to establish the differences between the two species. Thereby, the new species differs from C. pickelii, mainly in its prevailing orange-red primary bracts, sparsely and inconspicuously spinulose toward the apex, as well in its flowers with diurnal anthesis. Despite the slightly shorter size of the flowers, its pedicels are twice as long (ca. 4 mm vs. 2 mm) and the sepals are longer too ( ca. 24 mm vs. ca. 20 mm). In addition, the proportionally shorter petals of C. alagoanum (26-28 mm vs. 27-35 mm) are shorter to about equaling the primary bracts and remain suberect at anthesis, while in C. pickelii the petals are well protruded and distinctly surpass the primary bracts, becoming apically suberect-recurved to reflexed at anthesis. Another outstanding difference of the new species is the light yellow color of the petals and their well-developed basal appendages. In the night-blooming C. pickelii the petals are white and naked or bearing rudimentary appendages only.
Concerning pollen features, the new species differs from C. pickelii by its exine lumina which are irregular (vs. regular), polygonal (vs. rounded), larger, about 23 per µm² ( vs. ca. 18 per µm²) and by the wider aperture.
Conclusion
The rediscovery of C. pickelii in nature after 25 years and the discovery of C. alagoanum reveals four basic aspects of the situation in which the Atlantic Forest of the Northeast, North of the Sao Francisco River, finds itself, and of the level of taxonomical knowledge of Bromeliaceae:
1) It has been verified that an accelerated process of destruction of the few fragments of the Atlantic Forest biome that have survived in the Northeastern sector, North of the Sao Francisco River, is still underway despite the fact that only 2% of the original forest still exists (Teixeira, 1986).
2) It can be verified that very little is yet known about the floristic composition and biology of the species of these fragments. In fact, these fragments of Atlantic Forest, that form one of the five most threatened hotspots of the planet (Mittermeier et al. , 2000) and now give us a vague picture of the original vegetation of yesteryear, still hold a great variety of organisms that are little known or completely unknown to science. A good example is the discovery of five new species (Aechmea frassyi Leme & J. A. Siqueira, A. gustavoi J. A. Siqueira & Leme, A. marginalis Leme & J. A. Siqueira, Cryptanthus alagoanus Leme & J. A. Siqueira and Neoregelia pernambucana Leme & J. A. Siqueira) during the taxonomical research already reported (Siqueira & Leme, 2000; Leme & Siqueira, 2001 ).
3) It has also been verified that the perfection of taxonomical knowledge and the reconstruction of the phylogeny of Bromeliaceae are closely related to the increase of information provided especially in the field or with the maintenance in cultivation of live specimens. Research based only on herbaria samples is insufficient to fulfill the purpose of taxonomical and phylogenetic improvement of the Bromeliaceae, as exemplified by the recognition of C. alagoanum.
4) Finally, it can be concluded that an intensified and immediate effort to research and preserve the fragments of Atlantic Forest of Northeastern Brazil should be carried out, emphasizing groups of organisms such as Bromeliaceae that are known to be bio-indicators of biodiversity.
General notes
Canistrum is a genus of the subfamily Bromelioideae, typical of the Brazilian Atlantic Forest. It is distinguished by flashy and ornamental capitate and involucral inflorescences, with upper scape bracts and primary bracts disposed in a cup-shaped format. Its flowers are bird-pollinated and it has distinctly asymmetrical mucronate to spinescent sepals, (Leme, 1997; Siqueira, 1998). There are currently ten species grouped in two subgenera, Canistrum and Cucullatanthus (Leme, 2000; Luther, 2001). The overwhelming majority of species occur in the northeastern sector of the country, throughout the States of Pernambuco, Alagoas and Bahia, with just one species found in Espirito Santo in the Southeast (Leme, 1997; 2000).
In 1996, during the beginnings of the survey of Bromeliaceae in Pernambuco conducted by the first author in Brazilian herbaria (Siqueira, 2001 ), a specimen from the Empresa Pernambucana de Pesquisa Agropecuaria herbarium (IPA) soon attracted attention. It was the holotype of Portea pickelii, presenting a compact inflorescence and an unusual bract disposition that distinguished it considerably from all the species of Portea known at the time. Through comparison, it was possible to perceive the structural resemblance of its inflorescence to Canistrum aurantiacum, a typical species of Pernambuco.
Portea pickelii was described in 1970 by the late botanists Dardano de Andrade Lima and Lyman B. Smith, on the basis on a specimen collected in 1963 by the former, in the Mata do Camocim, in Pernambuco (Smith, 1970). In the protologue, the authors characterized the species as a plant that lived in the shaded areas of low open woods, differing from P. kermesina - that was according to them, the species with most morphological similarities by smaller leaf spines and short connate sepals with short mucronate apex.
After the conclusion of the revision of Canistrum (Leme, 1997), it became even more evident that P. pickelii was uncomfortably positioned in Portea. Curiously, the label of the holotype and also of the isotype (unclear on the latter), contains an identification by Andrade Lima himself that indicated the taxon as a new species of the genus Wittrockia. However, this initial conception by Andrade Lima, certainly intuitive and more natural from a phylogenetic point of view, was unrelated to the concepts of this genus that prevailed at the time.
In order to respond to the numerous questions regarding the taxonomical positioning of P. pickelii, field investigations aimed at finding its remaining populations were intensified. The search was initiated at the type locality, known as Mata do Camocim, belonging to the Ecological Station of Tapacurci, in the municipality of Sao Lourenco da Mata, that shelters stretches of seasonal semideciduous forest (sensu Vasconcelos Sobrinho, 1970). However, after several expeditions, no populations of P. pickelii were found. These probably became locally extinct due to the flooding caused by the Tapacurci dam. Finally, in January 1997, dense rupicolous and epiphytic populations of P. pickelii were found in Pernambuco in the forests of the Frei Caneca sugar-mill, in the municipality of Jaqueira, whose morphological traits were revealed to be perfectly adequate to the protologue of the species.
The study of these new populations has allowed deeper understanding of the taxonomical traits of the species, specially the floral morphology, but also of the phenological and floral biology. Also, the resumption of its studies and an expansion in field investigation, covering the neighboring state of Alagoas, gave rise to the recognition of another taxon, very similar to P. pickelii, but still unknown to science. So, taking the morphological, palynological, phenological and ecological information into account, it became clear that both should be placed within the genus Canistrum.
Materials and Methods
Besides several field expeditions between 1996 and 2001, the herbaria of the Empresa Pernambucana de Pesquisa Agropecuaria, Professor Dardano de Andrade Lima (IPA), Universidade Federal Rural de Pernambuco, Professor Vasconcelos Sobrinho (PEUFR) and Professor Sergio Tavares (HST), Universidade Federal de Pernambuco, Professor Geraldo Mariz (UFP), all in Pernambuco, Universidade Federal da Paraiba, Areia (EAN) in Paralba, Instituto do Meio-ambiente de Alagoas (MAC) and Universidade Federal de Alagoas (MUFAL) in Alagoas, Herbarium Alexandre Leal Costa (EAL) in Bahia, and the National Herbarium of the Botanical Department of the Smithsonian Institution in Washington, D.C. (US), were visited. (Three of the herbaria mentioned above (HST, MUFAL, and EAL) are not presently listed in the Index Herbariorum or on the electronic version available at http://www.nybg.org/bsci/ih/.)
For scanning electron microscope studies, plant material was dried using the critical point method. The material was coated with gold and observed in a SEM.
Herbarium material of the studied species collected by the authors were deposited in Herbarium Professor Geraldo Mariz (UFP) and Herbarium Bradeanum (HB), and living specimens were maintained in the author's collection in Recife and Rio de Janeiro.
Canistrum alagoanum occurs as an epiphyte in the coastal Atlantic Forest in the Maceio region and neighbouring areas, such as Paripueira. The fragmentation of the remaining forests which it inhabits are a serious threat and little different from the situation observed in Pernambuco for C. pickelii. Besides sugar cane, there is coconut production and urban expansion that is gradually eliminating the remaining forest —SeeJ. Bromeliad Soc.
