Belongs within: Heliconiinae.
Butterfly self defense
Published 24 December 2024
For many butterflies, their bright colours are aposematic indicators of their toxicity, broadcasting a warning to any potential predators. Often, these species feed on toxic plant species as caterpillars, sequestering the host plant’s toxins as they develop. However, there are some cases where butterflies are capable of generating toxic defenses of their own. Such is the case with the Acraeini.
Close to 300 species of Acraeini are known from tropical regions around the world, with over two-thirds of those species found in Africa (Silva-Brandão et al. 2008). They are slender-bodied, slow-flying butterflies with long, apically rounded wings. Males have straight, large, asymmetrical claws on the second pair of legs, with the ventral spines on the last tarsomere being irregularly spaced and pulvilli highly reduced or absent. Females have few sensilla on the first legs and the second tarsomere of these legs is less than one-third longer than the third (Penz & Peggie 2003). Classification has shifted about in recent years, but Williams & Henning (2023) recognised seven genera (plus Cethosia, an Oriental genus that has not been considered acraein by other authors) with Neotropical species assigned to a single genus Actinote.
Species of the Acraeini have been recorded feeding on a wide range of host plants (Silva-Brandão et al. 2008). Actinote species are, so far as we know, exclusive feeders on Asteraceae. Telchinia, a mostly African genus with one species found in Asia, has most commonly been found to feed on Urticaceae. The remaining African genera all focus on Passifloraceae. Phylogenetic analysis indicates that Passifloraceae were probably the ancestral food plant for the lineage. Host plants used by these basal lineages produce cyanoglycosides, seemingly the primary defensive chemical utilised by Acraeini. However, rather than having to sequester the compound from their host plants, Acraeini species are able to secrete cyanoglycosides de novo from a gland in their thorax. Presumably, early acraeins somehow evolved the ability to produce cyanoglycosides while feeding on Passifloraceae, then were able to continue producing these defensives after certain lineages transferred to non-cyanoglycoside-producing Urticaceae and Asteraceae. However, how this ability evolved, and just how the acraeins are able to do it, remains a question to be answered.
Systematics of Acraeini
<==Acraeini [Acraeinae]WWN03
|--ActinoteWWN03
| |--A. demonica (Hopffer 1874)S55
| |--A. lapithaFS54
| | |--A. l. lapithaFS54
| | `--A. l. zilchi Franz & Schröder 1954FS54
| |--A. leucomeles (Bates 1864)FS54
| `--A. stratoniceWWN03
`--Acraea Fabricius 1807B2000
|--A. acaraB1900
|--A. aliciaB01b
|--A. andromacha (Fabricius 1775)B12
|--A. anemosaB01a
|--A. buxtoniB1900
|--A. cabiraB01b
|--A. caeciliaB01b
|--A. doubledayiB1900
|--A. egina [incl. A. areca]B1900
|--A. horta [=Heliconius (Acraea) horta]G20
|--A. insignisB01a
|--A. jacksoniB01a
|--A. johnstoni [incl. A. johnstoni var. flavescens]B01b
|--A. masambaO90
|--A. mombasaeB02
|--A. lycia [incl. A. lycia var. daira]B01a
|--A. natalicaB01a
|--A. neobuleB01a
|--A. oblineataR13
|--A. onerataB01a
|--A. sambavaeO90
|--A. satisB01a
|--A. serena [incl. A. serena var. perrupta]B01a
`--A. uvuiB01b
*Type species of generic name indicated
References
[B2000] Braby, M. F. 2000. Butterflies of Australia: their identification, biology and distribution vol. 2. CSIRO Publishing: Collingwood (Victoria).
[B12] Braby, M. F. 2012. The butterflies of El Questro Wilderness Park, with remarks on the taxonomy of the Kimberley fauna, Australia. Records of the Western Australian Museum 27 (2): 161–175.
[B1900] Butler, A. G. 1900. On a second collection of butterflies obtained by Mr. Edward M. de Jersey in Nyasaland. Annals and Magazine of Natural History, series 7, 5: 59–63.
[B01a] Butler, A. G. 1901a. An account of a collection of butterflies made by the Rev. K. St. Aubyn Rogers between Mombasa and the forests of Taveta. Annals and Magazine of Natural History, series 7, 7: 22–35.
[B01b] Butler, A. G. 1901b. An account of a collection of butterflies obtained by Lord Delamere, chiefly at Munisu, near Mount Kenya. Annals and Magazine of Natural History, series 7, 7: 197–203.
[FS54] Franz, E., & H. Schröder. 1954. Tagfalter (Lep. Rhopalocera) aus El Salvador. Senckenbergiana Biologica 35: 75–87.
[G20] Goldfuss, G. A. 1820. Handbuch der Naturgeschichte vol. 3. Handbuch der Zoologie pt 1. Johann Leonhard Schrag: Nürnberg.
[O90] Oberthür, C. 1890. Note suivante. Annales de la Société Entomologique de France, 6e série 9: ccxli–ccxlii.
Penz, C. M., & D. Peggie. 2003. Phylogenetic relationships among Heliconiinae genera based on morphology (Lepidoptera: Nymphalidae). Systematic Entomology 28: 451–479.
[R13] Reuter, O. M. 1913. Lebensgewohnheiten und Instinkte der Insekten bis zum Erwachen der sozialen Instinkte. R. Friedländer & Sohn: Berlin.
[S55] Schröder, H. 1955. Eine Falter-Ausbeute aus dem westlichen Bolivien. (Ins. Lepid. Rhopal.) Senckenbergiana Biologica 36: 329–338.
Silva-Brandão, K. L., N. Wahlberg, R. B. Francini, A. M. L. Azeredo-Espin, K. S. Brown, Jr, M. Paluch, D. C. Lees & A. V. L. Freitas. 2008. Phylogenetic relationships of butterflies of the tribe Acraeini (Lepidoptera, Nymphalidae, Heliconiinae) and the evolution of host plant use. Molecular Phylogenetics and Evolution 46: 515–531.
[WWN03] Wahlberg, N., E. Weingartner & S. Nylin. 2003. Towards a better understanding of the higher systematics of Nymphalidae (Lepidoptera: Papilionoidea). Molecular Phylogenetics and Evolution 28: 473–484.
Williams, M. C., & G. A. Henning. 2023. Taxonomic revision of the tribe Acraeini Boisduval, 1833 (Papilionoidea: Nymphalidae: Heliconiinae). Metamorphosis 34: 35–49.