Species richness of anthophilous butterflies of an Atlantic Forest fragment in Southeastern Brazil

Os objetivos do presente trabalho foram identificar borboletas antófilas em flores psicófilas de quatro espécies de Asteraceae em um fragmento de Floresta Atlântica, no município de Viçosa, Minas Gerais, Sudeste brasileiro, e deter minar se existem espécies de borboletas em comum com outros levantamentos de lepidópteros do Sudeste e do CentroOeste do Brasil. É o primeiro inventário de borboletas antófilas de um fragmento de Floresta Estacional Semidecidual na Zona da Mata de Minas Gerais. Foram registradas 108 espécies, representando o quarto maior levantamento de lepidópteros de Minas Gerais. Esses resultados demonstraram que espécies de Ast rac ae podem ser importantes ferramentas para o monitoramento de borboletas antófilas. A similaridade com outros inventários variou de 1 a 92,55%. Quinze espécies foram reportadas pela primeira vez em Minas Gerais e, entre elas, M lani alena e Thisbe irenea foram observadas somente nesse estudo.


INTRODUCTION
Atlantic Forest is one of the most threatened and destroyed biomes of the planet.Today, the remaining forests cover about 100,000 km 2 , corresponding to 1% of the Brazilian territory (Fundação SOS Mata Atlântica, 2009).In the State of Minas Gerais, Southeastern Brazil, the Atlantic Forest covers about 10.33% of the territory (IEF, 2010), including the region known as Zona da Mata of Minas Gerais.
The municipality of Viçosa is located in the Zona da Mata and originally its vegetation consisted of continuous forests inserted in Atlantic Forest domains, which is classified as Montane Semideciduous Forest (Veloso et al., 1991).The original vegetation was replaced by coffee plantations for some time, and today the vegetation is predominantly pastureland covered with molasses grass (Mellinis minutiflora Beauv.) and secondary forests in different successional stages.
The forest reserve Mata do Paraíso, site of the present study, is the largest forest fragment in Viçosa.In the 19th century, after deforestation, it was partly replaced by coffee plantations and pastures.Nowadays, the forest in different succession stages covers an area of 194.36 ha (Pinto et al., 2007) and represents a vegetation island.
Added to the drastic reduction of the Viçosa's flora, only two studies involving the fauna of lepidopterous were carried out, both in Mata do Paraíso: inventories of the species Sphingidae and Arctiidae, but without relating the species to their host plants (Ferreira et al., 1986;1995).These surveys reported 21 new occurrences of Arctiidae in Minas Gerais.Recently, in studies performed by Godinho (2007), Lelis (2008), Cruz (2009) and Fonseca (2009), also carried out in Mata do Paraíso, four species of Asteraceae were described as pollinated by butterflies (psychophily) and the high number of species of these insects visiting their flowers motivated this study.
According to Mani & Saravanan (1999), about 75% of the Asteraceae species are psychophilous.Their floral characteristics, such as brightly colors, no perceptible odor, narrow tubular corolla and concealed nectar at the corolla base are conforming to the butterfly pollination syndrome.Besides, the aggregated arrangement of flowers on the inflorescence (capitulum), forming a landing platform, is another important attribute.
The objectives of this study were to identify anthophilous butterflies (visiting flowers and feeding on nectar), visitors of four Asteraceae species in the forest reserve Mata do Paraíso, and to compare the recorded lepidopteran species, especially butterflies, with other inventories of the Southeast and Midwest regions of Brazil.

Study site
The climate in the region of Viçosa (20°48'07"S and 42°51'31"W, 680 m) is characterized by a cold and dry season (from April to September), with monthly averages of 17 °C and 32 mm precipitation, followed by a hot and rainy season (from October to March), with monthly averages of 21 °C and 171 mm precipitation (Departamento Nacional de Meteorologia, 1992).
Specimens were killed by pinching the thorax, and then mounted and deposited at the Entomological Museum (Museu Regional de Entomologia), Departmento de Biologia Animal, Universidade Federal de Viçosa (UFV).Species were identified with specialists' assistance.
The species of this study were compared with those recorded in inventories of Minas Gerais State and the most representative inventories of São Paulo, Espírito Santo and Distrito Federal State, conducted in areas of Atlantic Forest, Cerrado and urban vegetation.

Collected anthophilous butterflies
A total of 108 anthophilous butterfly species were recorded on the flowers of four asteracean species in Mata do Paraíso, belonging to 70 genera, 16 subfamilies and five families (Table 1).Nymphalidae (48 species) and Hesperiidae (36 species) together represented 78% of the collected species.Among the subfamilies of Nymphalidae, Ithomiinae was represented by the largest number (23 species).For Hesperiidae, the subfamily Pyrginae was the most representative (19 species).Papilionidae, Pieridae and Riodinidae together accounted for about 22% of the surveyed species.

Comparison with other lepidopteran inventories
The 108 species recorded in this study, along with the 125 species of Sphingidae and Arctiidae identified in other surveys in Mata do Paraíso (MP), represent the fourth largest inventory of Lepidoptera in Minas Gerais, totaling 233 species (Table 2).Compared to other surveys in the same State (Table 2), this number of records is close to the inventory in the region of Belo Horizonte (269 species), in areas of semideciduous forest, Cerrado, rocky fields and urban areas; and in Uberlândia (251 species), in similar areas.On the other hand, the number of species detected in Mata do Paraíso is about 2.5-fold lower than in Poços de Caldas, where the most comprehensive inventory of Minas Gerais (572 species) in Atlantic Forest was carried out.
The similarity of the anthophilous Lepidoptera fauna of Mata do Paraíso with the other sites ranged from 1 to 92.55% (Table 3).Over 90% of the 94 identified species were also found in São Paulo State (SP).The inventory of this State, carried out in the same vegetation as Mata do Paraíso, is the most representative of all surveys involving Atlantic Forest (652 species) (Table 2).
Comparing the survey of Mata do Paraíso with two others conducted in Atlantic Forest (in Santa Teresa, ES) and in Cerrado (in Brasília, DF), a distinct biome (Table 2), a high similarity was found with respectively, 78.72% and 70.21% butterfly species in common (Table 3).
In the State of Minas Gerais, the highest degree of similarity with the inventory of Mata do Paraíso was observed with Poços de Caldas (PC) and Belo Horizonte (BH 1 ), 63.82 and 61.70%, respectively (Table 3).Among the inventories conducted in Minas Gerais, these two contained the most representative number of species (Table 2).Besides, 69.56% of the Ithomiinae species found in Mata do Paraíso were also reported in the study carried out in Juiz de Fora (JF) (Table 2).
When comparing our results with those of other inventories, we found that 15 species were first reported in Minas Gerais State (Table 1).Among the new records, Melanis alena (Hewitson, 1870) and Thisbe irenea (Stoll, 1780), both belonging to Riodinidae, occurred only in Mata do Paraíso.

DISCUSSION
The results presented in this study showed that plants (Asteraceae species) can be important tools for monitoring anthophilous insects, as suggested by Frankie et al. (2002).These authors monitored bee species on Bignoniaceae flowers in tropical areas of Costa Rica and California.Results confirming the usefulness of plants for monitoring anthophilous butterflies were published by Fonseca et al. (2006).These authors recorded 98 butterfly species on flowers of Stachytarpheta cayennensis (Rich.)Vahl.(Verbenaceae) and concluded that flowers of this species are critical for maintaining the community of Lepidoptera visitors.In this study, we focused on the species A. brasilianum and E. intermedium, belonging to genera regularly visited by Lepidoptera (Brown Jr., 1984a;1987;1992).
The richness of anthophilous butterflies in Mata do Paraíso may reflect the richness of the flora of the reserve, creating conditions for the survival of these insects.For butterflies in the adult stage, nectar is provided by psychophilous flowers, and other plants provide leaves for the larvae.For example, larvae of Nymphalidae, the most representative group of butterflies found in Mata do Paraíso, feed on leaves of Solanaceae, Apocynaceae and Passifloraceae (Brown Jr., 1992), families that are wellrepresented in the studied site (according to the collection of the VIC Herbarium).
The largest number of the butterfly species Nymphalidae and Hesperiidae confirmed their status as important pollinator group (Brown Jr., 1992;Fonseca et al., 2006;Godinho, 2007;Lelis, 2008;Cruz, 2009;Fonseca, 2009).The high number of Ithomiinae species may be due to the richness of Eupatorium (at least 11 species), in addition to the occurrence of A. brasilianum.Ithomiinae evolved the ability to assimilate pyrrolizidine alkaloids (PAs) from the nectar of these Asteraceae and transform them into compounds required to complete their life cycle (Brown Jr., 1984a;b;1987;Trigo et al., 1996;Paiva & Barata, 2004).This illustrates the importance of Asteraceae plants in maintaining butterfly populations in a given vegetation formation.
The low representation of anthophilous butterflies of the families Papilionidae and Pieridae was also observed in the study of Fonseca et al. (2006).These authors reported 11 species of Pieridae and four of Papilionidae and a large number of Hesperiidae (72 species) visiting flowers of S. cayennensis.This similarity with our results is probably due to characteristics the two study sites have in common (semideciduous forest).However, Fonseca et al. (2006) recorded only seven species of Nymphalidae, which may be related with the absence of PAs required by Ithomiinae in the nectar of S. cayennensis.
In our study, the few species of Riodinidae that were observed confirmed the study of Callaghan (1978), i.e., populations of these butterflies are characterized by frequency in low intensity.
Records of Thyridia psidii cetoides [= Thyridia psidii hippodamia (Fabricius)], very rare in disturbed forest (Brown Jr., 1992), indicate that Mata do Paraíso contains well-preserved habitats.The existence of this species at a given site may be related to the topography and preserved vegetation that support the persistence of relict populations, very rare or with few known populations (Brown Jr. & Freitas, 2000).These results show that in Mata do Paraíso, conditions are given for maintaining a high diversity of butterfly species, including some of the most demanding in terms of habitat conditions.In contrast, some subfamilies reported to be favoured by forest fragmentation by Uehara-Prado et al. (2003) were poorly registered in Mata do Paraíso (for example Biblidinae, represented by Biblis hyperia nectanabis (Fruhstorfer, 1909) and Temenis laothoe meridionalis Ebert, 1965).
The almost complete similarity between the butterfly species of Mata do Paraíso and São Paulo was expected.In the latter region, the survey was carried out in an area of 10,000 ha with mainly the same semideciduous forest vegetation as in former one (Brown Jr., 1992;Leitão-Filho, 1992), a factor that raises the chances of recording species in common.These results and other studies reporting high similarities showed that more representative inventories of the butterfly fauna of a given site increase the chances of recording species in common, regardless of the type of vegetation.
This latter finding shows that the habitat of many butterflies comprises forests and open and dry areas, such as Cerrado.According to Brown Jr. & Freitas (2000), species of Papilionidae, Pieridae and Nymphalidae observed in Mata do Paraíso occur in Cerrado, Atlantic Forest, on the coast of Bahia, in inland mountainous areas and especially in the coastal plain of "Baixada Fluminense", Rio de Janeiro, Rio de Janeiro State.The capacity of these butterflies to explore different habitats and, consequently, different abiotic conditions resulted in their wide geographic distribution.
The richness of Lepidoptera in Mata do Paraíso was certainly underestimated, since frugivorous butterflies and diurnal and nocturnal moths were not included, except Sphingidae and Arctiidae (Ferreira et al., 1986;1995).The 15 new records increase the richness of the lepidopteran fauna of Minas Gerais and reveal the lack of systematic inventories to represent its diversity.The finding of two butterflies only in Mata do Paraíso (M.alena and T. irenea) indicates an apparently greater environmental restriction of these insects or their low frequency (Callaghan, 1978), which may hamper sampling by the low number of individuals, as they are not protected as rare or endangered species (Casagrande et al., 1998;Brown Jr. & Freitas, 2000;Machado et al., 2008).
The proportions of species in families and subfamilies of butterflies in tropical forests of Central and South America are relatively constant (Beccaloni & Gaston, 1995).These authors argued that there is a strong positive correlation between species richness of Ithomiine and the overall species richness of all other butterflies across all areas, and the proportion of Ithomiinae (as an indicator group) is reasonably invariant.They concluded that it should be possible to use the mean proportion (4.6%) to predict the overall butterfly species richness of an area for which the total number of Ithomiine is known.
Based on these statements and on the identification of all Ithomiinae in Mata do Paraíso (23 species) by the current inventory, the richness of this fragment would be 500 butterfly species distributed in different families and subfamilies.This estimate, if confirmed, highlights the relevance of this fragment in maintaining the lepidopteran population and indicates the need of further similar work to understand the richness of its Lepidoptera fauna.
In this paper, we present the first inventory of anthophilous butterflies of a semideciduous forest fragment in the Zona da Mata, Minas Gerais State.It includes 15 new records for the State, two of which restricted to the study site, and it shows the importance of forest fragments, particularly of the forest reserve Mata do Paraíso, as a last refuge for these insects.The survival of butterflies depends on the conservation of plants, as nectar source for the adults and leaves for the larvae.It is noteworthy that the mutualistic interactions between butterflies and psychophilous flowers, including those in Mata do Paraíso, call for further investigation.

CONCLUSIONS
Asteraceae species, especially E. intermedium, B. segetum and A. brasilianum, are important tools for monitoring anthophilous butterflies.
In these plants, 108 butterflies species were collected, belonging to 70 genera, 16 subfamilies and five families, representing the fourth largest lepidopteran survey of Minas Gerais State.
There is high similarity (above 60%) among the species of butterflies anthophilous of Mata do Paraíso and of the lepidopteran inventories made in Southeastern and Midwestern regions of Brazil, regardless of the type of vegetation.

Table 2 .
Lepidoptera inventories conducted in Distrito Federal, Espírito Santo, Minas Gerais and São Paulo: vegetation of study sites and number of collected species Data of Viçosa (MP) include 108 species of this study plus 125 Sphingidae and Arctiidae species identified in other surveys. 1

Table 3 .
Families , subfamilies and number of butterfly species (Lepidoptera: Rhopalocera) in common between the Seasonal Semideciduous Forest in the forest reserve Mata do Paraíso, Viçosa (MP) and other areas in Minas Gerais, São Paulo, Espírito Santo and Distrito Federal (for abbreviations, see Table2)