THE DIVERSITY AND DISTRIBUTION OF HELICONIA ( HELICONIACEAE ) IN BRAZIL

A review of the phylogenetic relationships of the Zingiberales is pres~nted and the distribution patterns and diversity of Heliconia are discussed. Sixty-five species names have been applied to the heliconias that occur in Brazil. Of these 6S names, 28 are generally recognized synonyms. Of the remaining 37 species of Brazilian Heliconia, some controversy exists over the taxonomic status of at least eight. Two primary areas of distribution of species of Heliconia exist in Brazil: the Amazon basin (21 species) and the AtlanÚc coas tal forest (20 species). Key-words: Zingiberales, Heliconia, diversity, distribution.


Results and discussion
The Zingiberales Heliconia is the only genus in the plant family Heliconiaceae, which is a member of the order Zingiberales (earlier called the Scitamineae).In addition to the several cellular features (short root hair cells, sieve tube plastids with starch, silica bodies, inaperturate and exineless pollen) that distinguish the Zingiberales from other monocots, there are several very conspicuous characters by which they can be recognized, including, 1) large leaves with long petioles and blades possessing transverse venation, 2) large, usually colorful, bracteate inflorescences, and 3) arillate seeds.This order is most closely related to the family Bromeliaceae and their relatives in the superorder Bromeliiflorae (Dahlgren, Clifford & Yeo, 1985;Kress, 1990b).
Most current taxonomists (see Kress, 1990b) recognize eight separate families in the Zingiberales: Musaceae, Strelitziaceae, Lowiaceae, Heliconiaceae, Zingiberaceae, Costaceae, Cannaceae, and Marantaceae.Most of the members of these eight families are native to the tropical regions of the earth and many are found in Brazil.
F AMIL Y MUSACEAE.Native species of the two genera of the banana family, Musa (35 species) and Ensete (7 species), are restricted to the paleotropics of Africa, eastern Asia, Australia, and the South Pacifico However, both genera have been extensively cultivated and hybridized for thousands of years and are now distributed around the world.In Brazil, many cultivars of edible bananas (triploids of M. acuminata) and plantains (hybrids of M. acuminata x paradisiaca) are grown.
F AMIL Y STRELITZIACEAE.The three genera and seven species of the family, Strelitzia (five species), Ravenala (one species), and Phenakospermum (one species), are restricted to southern Africa, Madagascar, and South American.respectively.The latter genus is native to Amazonian Brazil.The birdsof-paradise (Strelitzia reginae and Strentzia nicolai) and traveller's paIm (Ravenala madagascariensis) are common1.ygrown as landscape and greehhouse ornamentaIs throughout tropical América, including Brazil.
FAMILY LOWIACEA:E.The single genus of the family, Orchidantha, with five to eight species, is found in Southeast Asia and some Pacific Islands.Orchidantha has always been considered an unusual member of the Zingi-berales and is among the most poorly known taxa in the order in terms of botany and horticulture.
FAMILY HELICONIACEAE.Heliconia has been variously associated with the Musaceae or the Strelitziaceae, but is now placed in its own family Heliconiaceae.The inverted flowers, the presence of a single staminode, and the drupaceous fruits are special features of Heliconia.Many species and varieties native to Brazil are now being grown as pot plants and as cut-flowers.
FAMILY ZINGIBERACEAE.The Zingiberaceae, the largest family in the Zingiberales, consist of approximately 50 genera and 1000 species.Gingers are found in all tropical regions of the world, but are concentrated in the Old W orld, especially in Southeast Asia.Only one genus, Renealmia, is found in the neotropics (one-third of the genus occurs in Africa) with about eight species found in Brazil (Maas, 1977).
FAMILY COSTACEAE.The Costaceae, consisting of four genera and about 150 species, are distributed throughout the Asian, African, andAmerican tropics.The largest genus Costus (100 species) is most diverse in the American tropics, but is also found in Africa, Asia, and northern Australia.Monocostus (one species) and Dimerocostus (two species) are restricted to the New W orld tropics.Tapeinochilos (20 species) extends through New Guinea, Indonesia and tropical Australia.Only the genus Costus is found in Brazil with a center of diversity in Pará (Maas, 1972).The Costaceae in the past have been classified as a subdivision of the Zingiberaceae, but are now accepted by the majority of taxonomists as a separate family.
FAMILY CANNACEAE.Canna, the solitary genus in the family, is primarily found in the New World tropics and subtropics.Estimates on the number of species in Canna range from 10 to 60 (Maas & Maas, 1988).Probably three species occur in Brazil.
F AMIL Y MARANT ACEAE.The Marantaceae are the second largest family in the order with 30 genera and 450 to 500 species.Although members of this family are found throughout the tropics, three-quarters of the species, many in the large genus Calathea, are found in the neotropics.Of the 14 genera occuring in South America, 11 are represented in Brazil.Among the Brazilian genera, two are endemic to Brazil (Saranthe, Koernickanthe) , five have their major centers of diversity in Brazil (Monotagma, Hylaeanthe, Maranta, Cte- nanthe, Myrosma), and three have at least one secondary center of diversity in Brazil(Calathea, Ischnosiphon, Stromanthe} (Andersson, 1977(Andersson, , 1981b;;H. Kennedy, pers. comm.).Many members of the Marantaceae (e.g., Maranta, Ca- lathea, Stromanthe, and Ctenanthe) endemic to Brazil (especially the Atlantic coastal forests) are cultivated as ornamentaIs.

Habitat and distribution of Heliconia
Heliconias are native primarily in the American tropics from the Tropic of Cancer in Central Mexico to the Tropic of Capricorn in South America, including the Caribbean.A curious disjunct group of six species of Heliconia separated by thousands of miles from most other species is found in the Old World tropics (Kress, 1985(Kress, , 1990a)).The center of diversity of the genus is found along the northern Andes (Colombia and Ecuador) extending into southern Central America (Panama and Costa Rica;Andersson, 1989).Most species inhabit moist or wet regions, but some are found in seasonally dry areas.AIthough heliconias attain their most luxuriant vegeta tive" growth in the humid lowland tropics at elevations below 500 meters, the greatest numbers of species (many locally endemic) are found in middle-elevation (800-1,500 meters) rain and cloud forest habitats.Few species occur above 2000 meters.
The most conspicuous members of the genus inhabit open sites in secondary growth along roadsides, on river banks, and in forest light gaps.With increased destruction by man of the tropical rain forest, these species readily invade and colonize the newly opened areas.Other species never attain such extensive vegeta tive growth and are restricted tn the more shaded habitats of the primary forest.These latter species are often locally endemic and are fast becoming extinct as destruction of the tropical forest accelerates.

Classification of Heliconia
Over the past 100 years several infrageneric classifications of Heliconia have been proposed; each one has been more complex than its predecessors.(Kress, 1984).Until recently the classification recognized by most workers is the one proposed by Griggs in 1915.His classification consists of two subgenera and six subordinate taxa of unspecified rank.Plant habit and height, inflorescence orientation, cincinnal bract orientation, and the distance between adjacent bracts are characters he used to define subgeneric groups.
Andersson (1985a, b) has proposed a new, slightly different classification of the genus in which the ranks and arrangement of Griggs' taxa are changed (Table 1).Andersson's subgenera and sections are more carefully defined and circumscribed than those ofGriggs.Although he has not discussed the phylogenetic relationships of his taxa nor provided evidence that his subgenera and sections are monophyletic, Andersson's system is a great improvement on the system of Griggs.A detailed analysis of the classification of subgen.Griggsia, one of the largest taxa that is made up of species possessing pendent in florescences, is in progress (Kress, unpubl.).

Diversity and distribution of Heliconia in Brazil Kress
He/iconia bihai, a widespread neotropical species, was published by Linnaeus in 1771 and is therefore the earliest name for a species occuring in Brazil.However, the earliest name for an endemic Brazilian heliconia, H. angusta, was published by Vellozo in 1825 in Flora F/uminensis (Emygdio, 1975).Since that time many new taxa have been described and many new names have been published for Brazilian heliconias.The Brazilian botanists Dr. Luiz Emygdio de Mello Filho, Dr. Emilia Santos, and Dr. Humberto de $óuza Barreiros have been instrumental in furthering our understanding of the native taxa.
Sixty-five species names have been applied to the heliconias that occur in Brazil.Of these 65 names, 28 are generally recognized synonyms.Of the remaining 37 species of Brazilian Heliconia, some controversy exists over the taxonomic status of at least eight.For example, Andersson (1985a) has synonomized with H. angusta five species described from the Atlantic coastal forests.Estimates of the number of Heliconia species in Brazil therefore ranges between 29 and37.
Thirty-seven is a relatively low number of species of He/iconia for a country the size of Brazil with so many diverse habitats, especially when compared to the number of taxa found in some of the smaller Andean and Central American countries (e.g., 39 species in Costa Rica; 4S species in Ecuador).This low number is most likely the result of historical factors of distribution of Heliconia (i.e., the Andean-Central American center of diversity) and not environ- mental variables.
Two primary areas of distribution of species of Heliconia exist in Brazil (Table 2): the Amazon basin (21 species) and the Atlantic coastal forests (20 species).The species occuring in each of these general regions can be classified as endemic to one of these regions, disjunct between one of these regions and some other region (e.g., the Guianas, the Planalto), ar widespread (found in more than one region of South America) (see Table 2).
With respect to the species found in the Amazon basin, eight (38%) are endemic to the Amazonian region in the broad sense.Only two of these species (H.ade/iana and H. auriculata) are endemic to Brazil (and both are taxonomically controversial).Eight species (38%) are widespread throughout South America; four (19%) are found in the Amazon region and the Guianas; and one is distributed in the southern Amazon region and parts of the Planalto.Of the 20 species found in the Atlantic coastal rain forests of Brazil, 14 (70%) are endemic to the region.Even if one accepts Andersson's many synonyms for He/iconia angusta, the region is exceptionalIy high in endemics.This high degree of endemism for heliconias in the coas tal forests is similar to the patterns of distribution of forest trees reported by Mori, Boom and Prance (1981).Of the remaining species of Heliconia in this region, four (20%) are widespread and two (10%) are also found in the Guianas.
There is at least one species of Brazilian Heliconia in each taxonomic category in Andersson's classification of the genus (Table 1).This distribution of species suggests that alI of the major lines of evolution within the genus have radiated into Brazil.The broad taxonomic representation is also true if just the Amazonian species are considered.However, in the Atlantic coastal forests, only one-half of the taxonomic categories are represented.The high incidence of endemics in this region is mostly the result of diversification in Subgen.Stenochlamys Sect.Stenochlamys (the H. angusta complex) and Subgen.He/iconia Sect.Novo 11 (the H.farinosa complex).
In conclusion, Brazil is not exceptionally species rich for the genus Heliconia.Species that are endemic occur primarily in the Atlantic coastal rain forests and represent principally two taxonomic groups in the genus.It is doubt-fuI that many new species are still to be found in Brazil relative to the great number of new taxa being discovered in the Andean regions of Ecuador, Colombia, and Peru.
However, for the Brazilian heliconias, further systematic and evolutionary studies are certainly warranted.For example, investigations of reproductive biology and plant-pollinator relationships have not yet been thoroughly studied in Brazilian species.Moreover, studies on genetic diversity using isozyme electrophoresis and nucleic acid variation, especially in the Atlantic coastal species (e.g.,the H. farinosa complex and H. angusta complex) should prove to be particularly interesting and informa tive for an understanding of species boundaries and the processes of speciation in these plants.

Table 2 .
Geographic Distribution of Heliconia which occur in Brazil.