There are 42 species of Heliconius and a total of 69 species among the Passion flower butterflies of the Americas, which form the sub-tribe Heliconiini and include eight related genera. There is an up to date classification of the nymphalid butterflies available here.
Agraulis, Dione, Podotricha, Dryadula, and Dryas, termed the ‘basal’ genera by Brown (1981), have the wing venation of the discal cell of the hind wing open. These open cell heliconiines are relatively palatable, and so generally fast flying to avoid predation. Also, their highly dispersive populations are associated with open sunny habitats, where they visit unspecialised butterfly-pollinated flowers with short corollas and large floral displays (e.g. Lantana).
The remaining genera Eueides and Heliconius (we here subsume the genus Laparus and Neruda into Heliconius), termed the ‘advanced genera’ by Brown (1981), are the most diverse in terms of numbers of species. All of these possess a closed hind wing discal cell. The closed-cell genera, Eueides and Heliconius are relatively unpalatable, warningly coloured and slow flying. Their wing patterns are simple and composed of a few striking pattern elements adapted for warning colouration.
In the last sixty years seven major studies have addressed the systematics of the passion-vine butterflies (Brower, 1994; Brower & Egan, 1997; Brown, 1981; Emsley, 1963; Emsley, 1965; Michener, 1942; Penz, 1999). These phylogenetic hypotheses are in conflict with one another, in particular with regard to the relationships among the genera Heliconius, Eueides, Neruda and Laparus, leading to disagreement over the origin of the derived behavioural trait, pollen feeding.
The most recent attempt to resolve the phylogenetic relationships in the group, using molecular markers, showed that Heliconius is paraphyletic, with Laparus doris and Neruda falling within the genus (Beltran et al., 2007). This suggests a single origin for pollen feeding but with a loss of the trait in Neruda. However, different genes are not congruent in their placement of Neruda therefore monophyly of the pollen feeding species cannot be ruled out. There was also a highly supported pupal-mating clade (H. erato, H. sapho and relatives) suggesting that pupal-mating behaviour evolved only once. In addition, there were three independent origins for larval gregariousness from a solitary ancestor, showing that gregarious larval behaviour arose after warning coloration.
Beltran M, Jiggins CD, Brower AVZ, Bermingham E, Mallet M. 2007. Do pollen feeding, pupal-mating and larval gregariousness have a single origin in Heliconius butterflies? Inferences from multilocus DNA sequence data. Biological Journal of the Linnean Society in press.
Brower AVZ. 1994. Phylogeny of Heliconius butterflies inferred from mitochondrial DNA sequences (Lepidoptera: Nymphalidae). Molecular Phylogenetics and Evolution 3: 159-174.
Brower AVZ, and Egan MG. 1997. Cladistics of Heliconius butterflies and relatives (Nymphalidae: Heliconiini): the phylogenetic position of Eueides based on sequences from mtDNA and a nuclear gene. Proc. R. Soc. Lond. B 264: 969-977.
Brown KS, Jr. 1981. The biology of Heliconius and related genera. Ann. Rev. Entomol. 26: 427-456.
Emsley M. 1963. A morphological study of imagine Heliconiinae (Lep.: Nymphalidae) with a consideration of the evolutionary relationships within the group. Zoologica NY 48: 85-130.
Emsley MG. 1965. Speciation in Heliconius (Lep., Nymphalidae): morphology and geographic distribution. Zoologica, New York 50: 191-254.
Michener CD. 1942. A generic revision of the Heliconiinae (Lepidoptera, Nymphalidae). Amer. Mus. Novit. 1197: 1-8.
Penz CM. 1999. Higher level phylogeny for the passion-vine butterflies (Nymphalidae, Heliconiinae) based on early stage and adult morphology. Zoo. J. Linn. Soc. 127: 277-344.