Acraea (butterfly)

Acraea is a genus of brush-footed butterflies (family Nymphalidae) of the subfamily Heliconiinae. It seems to be highly paraphyletic and has long been used as a "wastebin taxon" to unite about 220 species of anatomically conservative Acraeini. Some phylogenetic studies show that the genus Acraea is monophyletic if Bematistes and Neotropical Actinote are included (see Pierre & Bernaud, 2009). Most species assembled here are restricted to the Afrotropical realm, but some are found in India, Southeast Asia, and Australia.[2]

As invalidly established by Hübner in 1819, Acraea also refers to butterflies currently placed in Actinote

Acraea
Adult male fiery acraea (A. acrita)
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Nymphalidae
Tribe: Acraeini
Genus: Acraea
Fabricius, 1807
Type species
Papilio horta
(Linnaeus, 1764)
Species

Presently about 220, see text

Synonyms

[1]
Alacria Henning, 1992
Aphanopeltis Mabille, 1887
Auracraea Henning, 1993
Aurora Henning, 1992 (non Ragonot 1887: preoccupied)
Gnesia Doubleday, 1848
Hyalites Doubleday, 1848
Pareba Doubleday, 1848
Phanopeltis Mabille, 1887
Planema Doubleday, 1848
Rubraea Henning, 1992
Solenites Mabille, 1887
Stephenia Henning, 1992
Telchinia Hübner, 1819
(but see text)

Biology
Acraea zetes larva, pupae and imago

The eggs are laid in masses; the larvae are rather short, of almost equal thickness throughout, and possessing branched spines on each segment, young larvae group together on a protecting mass of silk; the pupa is slender, with a long abdomen, rather wide and angulated about the insertion of the wings, and suspended by the tail only. A. horta, A. cabira, and A. terpsicore illustrate typical life histories. The food plants of Acraea caterpillars are usually Urticaceae or, like in most Heliconiinae, Passifloraceae. Some feed on other plants, such as Fabaceae, "Flacourtiaceae", or Violaceae. Their preferred species contain cyanogenic glycosides, which make the larvae and adults poisonous to predators. The aposematic coloration of the adults announces this, and some species are mimicked by less noxious butterflies. At least some "Acraea" are able to produce the toxins themselves.[2] Their flight is slow and flapping.

Systematics and taxonomy

That all these species were properly placed in Acraea has never been generally accepted. In 1807, Johan Christian Fabricius established the genus for the garden acraea, described as Papilio horta by Carl Linnaeus in 1764, and its relatives. By and by, an increasing number of species were placed here. As early as 1848, and again in 1887 and the early 1990s, it was attempted to divide the genus into groups of closest relatives, as it was suspected that some "Acraea" might actually be closer to other genera in the tribe Acraeini.[3]

With increasing availability of DNA sequence data, it is confirmed that Acraea as loosely defined does not constitute a monophyletic group. Even before the attempts to split up Acraea in earnest had begun, Jacob Hübner in 1819 suggested to separate species around Acraea serena as Telchinia. This name has been applied to a generally African group whose members usually feed on Urticaceae, and they had already been noted to bear some uncanny resemblances to the American Actinote in anatomical details. Indeed, they seem to be closer relatives of these than of the other butterflies placed in Acraea, which usually feed on Passifloraceae and are at least in part quite close relatives of the African genus Bematistes. Those closest to that genus might warrant separation as Rubraea or Stephenia.[3]

But while several informal species groups have been established, it is not clear which of these are monophyletic and how to split the apparently still paraphyletic genus further. The placement of the garden acraea—the type species—and hence which of the any further subdivisions will get to bear the name Acraea, remains unresolved. As it is traditionally included in the former A. terpsicore group (now A. serena group) and its caterpillars, while polyphagous, do not feed on Urticaceae, it may be that the separation of Telchinia is unwarranted and other proposed genera might be resurrected instead.[1]

There was one major misidentification which still causes confusion today. Acraea terpsicore, described as Papilio terpsicore by Linnaeus in 1758, was held to be the senior synonym of A. serena, described by Fabricius as Papilio serena in 1775. Hence, the former name was commonly used for that African species. But as it turned out, Linnaeus had actually described an Indian species—the well-known tawny coaster. Fabricius in 1793 believed it was new to science and described it again, as Papilio violae. Consequently it had been long known as A. violae. It was also recognized that Fabricius' little-studied P. serena was none other than the orange acraea. For this, the name A. eponina, from the Papilio eponina established in the 1780 issue of Pieter Cramer's De uitlandsche Kapellen, had been used all the time.[4] Another instance of the confusion rife in this genus is exemplified by Boisduval's Acraea manjaca.

These developments come from two papers written by J. Pierre and D. Bernaud.[5][6]

Species

Since the proposed phylogenetic sequence of the species groups is almost certainly incorrect for a large part, the groups are simply listed alphabetically.[7]

J. Pierre & D. Bernaud have published a complete systematic and synonymic list.[8]

[4]

Small greasy (A. andromacha)

Acraea acrita species group

Acraea andromacha species group (close to part of A. terpsicore group?)

Acraea anemosa species group

Acraea aureola species group

A. cabira

Acraea bonasia species group (close to A. oberthuri and A. rahira groups? Paraphyletic?)

Acraea caecilia species group (close to A. cepheus and A. egina groups?)

Acraea ranavalona mating, Anjajavy Forest, Madagascar

Acraea cepheus species group (close to A. caecilia and A. egina groups?)

Tawny coster (হরিনছড়া), Acraea violae
Acraea grosvenori

Acraea circeis species group (close to A. masamba)

Common acraea (A. encedon)

Acraea egina species group (close to A. caecilia and A. cepheus groups?)

Acraea encedon species group (close to A. jodutta and A. pharsalus groups?) – common acraea or white-barred acraea or encedon acraea

Acraea issoria species group (a rather distinct lineage?)

Acraea amicitiae

Acraea jodutta species group (close to A. encedon and A. pharsalus groups?)

Dusky-veined acraea (A. dammii)

Acraea masamba species group (close to A. circeis?)

Acraea oberthuri species group (close to A. bonasia group?)

Acraea pentapolis species group (close to A. circeis and A. masamba groups?)

Acraea pharsalus species group (close to A. encedon and A. jodhutta groups?)

Acraea rahira species group (close to A. bonasia group?)

Garden acraea (A. horta) pupa (left) and caterpillar

Acraea satis species group

Tawny costers (A. terpsicore) mating

A. terpsicore group

Garden acraea (A. horta, the type species of the genus)

Acraea terpsicore species group (formerly A. violae group)

Acraea zetes species group (might include part of A. serena group; a very distinct lineage?)

Species group undetermined

Some other species formerly in Acraea have now been definitely assigned to other genera, e.g. Bematistes.

Footnotes
  1. See references in Haaramo (2007)
  2. Silva-Brandão et al. (2008)
  3. Pitkin & Jenkins (2004), Silva-Brandão et al. (2008). See also references in Haaramo (2007).
  4. Silva-Brandão et al. (2008); see also references in Haaramo (2007)
  5. http://acraea.com/image/liste/Acraea_terpsicore.pdf
  6. http://acraea.com/image/pdf/serena_01.pdf
  7. Woodhall (2005)
  8. http://acraea.com/image/liste/systematique.pdf

References

Further reading
  • Eltringham, H., 1912 A Monograph of the African species of the Genus Acraea, Fab., with a supplement on those of the Oriental Region. Transactions of the Royal Entomological Society of London Volume 60, Issue 1, pages 1–369, July 1912 pdf
  • Pierre J. & Bernaud D., 2009. Butterflies of the World, Part 31, Nymphalidae XVI et Supplément 16, Acraea sous-genre Actinote. Erich Bauer. Thomas Frankenbach, Goecke & Evers, Keltern, Germany ISBN 9783937783390
  • Pierre J. & Bernaud D., 2013. Butterflies of the World, Part 39, Nymphalidae XXIII et Supplément 22, Acraea sous-genre Acraea . Erich Bauer. Thomas Frankenbach, Goecke & Evers, Keltern, Germany ISBN 9783937783666
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