Ithomiini is a butterfly tribe in the nymphalid subfamily Danainae. Some authors consider the group to be a subfamily (Ithomiinae). These butterflies are exclusively Neotropical, found in humid forests from sea-level to 3000 m, from the southwestern United States to Argentina. There are around 370 species in some 40–45 genera.
Ithomiines are unpalatable because their adults seek out and sequester pyrrolizidine alkaloids from plants that they visit, especially composit flowers (Asteraceae) and wilted borages (Boraginaceae). The slow-flying adults are Müllerian mimics of each other as well as of many other Lepidoptera. Identification of adult ithomiines relies on hindwing venation and male androconial scales (sex brushes located on the hindwing costa).
The group has repeatedly been proposed as biological indicators of ecological conditions or biological diversity within neotropical forests, but individual sites harbor between 10 and 50 species, for the most part, and beta diversity is often great, even over relatively short distances.
Ithomiine larvae feed mostly on Solanaceae host plants. Exceptions are the more basal genera Tithorea, Aeria, and Elzunia that, like Tellervo and some Danainae, feed on Echiteae vines (Apocynaceae, Apocynoideae), as well as Megoleria and Hyposcada that feed on Gesneriaceae.
The local abundance of ithomiine butterflies in the Amazon forest, the lack of observations of predation, and their “peculiar smell” led Henry Walter Bates in 1867 to suggest that these organisms should be chemically defended. This was first experimentally demonstrated in 1889 when Thomas Belt fed ithomiines (that he called “Heliconii”) to birds, the spider Nephila, and the white faced monkey Cebus capucinus. The butterflies were consistently rejected, but other insects were eaten. Lincoln P. Brower in 1964 also showed that adults of Ithomia drymo pellucida were rejected by the bluejay Cyanocitta cristata bromia, and Haber showed that nine species of birds also rejected several ithomiine species. Besides, Vasconcellos-Neto and Lewinsohn demonstrated that the neotropical orb-weaving spider Nephila clavipes released unharmed 14 species of field-caught ithomiine butterflies.
The source of the protecting chemicals in the bodies of adult ithomiines proved not to be their larval host plants, as was first suggested, but rather in plants visited by the butterflies. Adults of ithomiine, mainly males, visit flowers of some Boraginaceae, (Tournefortia, Heliotropium), Asteraceae (mostly in the tribe Eupatorieae, and rarely on Senecio species), Apocynaceae (Prestonia, belonging to the tribe Echiteae) and Orchidaceae (Epidendrum paniculatum). Dead or withered plants are also visited and, when feeding on these plants, the butterflies scratch the tissues with their legs and suck the oozing sap. These plants are known to contain pyrrolizidine alkaloids, indicating their role as chemical sources for sequestration. Other butterfly and moth species that sequester pyrrolizidine alkaloids (Danainae, Ctenuchidae, and Arctiidae) also visit similar sources. The first demonstration that pyrrolizidine alkaloids were involved in the chemical defense of insects was given by Thomas Eisner, who showed that the spiders Nephila and Argiope rejected adults of the arctiid moth Utetheisa ornatrix that contain pyrrolizidine alkaloids from their larval host plant, Crotalaria (Fabaceae: Crotalarieae). Eisner's best-selling popular science book For love of insects tells the story of this exciting discovery.
The subtribes in the Ithomiini help to organize the 43 recognized genera, but this group is the subject of ongoing molecular, phylogenetic, and morphological research, and the classification presented below will no doubt be refined in the near future.
The sister group to the tribe Ithomiini is either the small tribe Tellervini (containing the single Australasian genus Tellervo) or the larger tribe Danaini. The relationships of the three tribes in the subfamily Danainae are still unclear.
- Source: The higher classification of Nymphalidae, at Nymphalidae.net
- Note: A species list with proposed new tribes for subfamily Ithomiinae is available from Keith Willmott at .
- Note: Names preceded by an equal sign ( = ) are synonyms, homonyms, rejected names or invalid names.
Tribe Ithomiini Godman & Salvin, 1879
- (Subtribe Tithoreina Fox, 1940)
- (Subtribe Melinaeina Clark, 1947)
- (Subtribe Mechanitina Bar, 1878)
- Methona Doubleday 1847 ( = Gelotophye d’Almeida 1940)
- Thyridia Hübner 1816 ( = Xanthocleis Boisduval 1870; = Aprotopus Kirby 1871; = Aprotopos Kirby 1871)
- Scada Kirby 1871 ( = homonym Salacia Hübner 1823; = Heteroscada Schatz 1886)
- Sais Hübner 1816
- Forbestra Fox 1967
- Mechanitis Fabricius 1807 ( = homonym Nereis Hübner 1806; = unavailable name Hymenitis Illiger 1807; = Epimetes Billberg 1820)
- (Subtribe Napeogenina)
- Aremfoxia Réal 1971
- Epityches d'Almeida 1938 ( = homonym Tritonia Geyer 1832)
- Hyalyris Boisduval 1870 ( = Oreogenes Stichel 1899)
- Napeogenes Bates 1862 ( = homonym Ceratonia Boisduval 1870; = Choridis Boisduval 1870)
- Hypothyris Hübner 1821 ( = Mansueta d'Almeida 1922; = Pseudomechanitis Röber 1930; = Garsauritis d'Almeida 1938; = Rhodussa d'Almeida 1939)
- (Subtribe Ithomiina Godman & Salvin, 1879)
- (Subtribe Oleriina)
- (Subtribe Dircennina d'Almeida, 1941)
- Ceratinia Hübner 1816 ( = Calloleria Godman & Salvin 1879; = Epileria Rebel 1902; = Teracinia Röber 1910)
- Callithomia Bates 1862 ( = Cleodis Boisduval 1870; = Epithomia Godman & Salvin 1879; = Corbulis Boisduval 1870; = Leithomia Masters 1973)
- Dircenna Doubleday 1847
- Hyalenna Forbes 1942
- Episcada Godman & Salvin 1879 ( = Ceratiscada Brown & d’Almeida 1970; = Prittwitzia Brown, Mielke & Ebert 1970)
- Haenschia Lamas 2004
- Pteronymia Butler & Druce 1872 ( = Ernicornis Capronnier 1874; = Parapteronymia Kremky 1925; = Talamancana Haber, Brown & Freitas 1994)
- (Subtribe Godyridina)
- Velamysta Haensch 1909
- Godyris Boisduval 1870 ( = Dismenitis Haensch 1903; = Dygoris Fox 1945)
- Veladyris Fox 1945
- Hypoleria Godman & Salvin 1879 ( = homonym Pigritia d’Almeida 1922; = homonym Pigritina Hedicke 1923; = homonym Heringia d’Almeida 1924)
- Brevioleria Lamas 2004
- Mcclungia Fox 1940
- Greta Hemming 1934 ( = homonym Hymenitis Hübner 1819; = Hypomenitis Fox 1945)
- Heterosais Godman & Salvin 1880 ( = Rhadinoptera d'Almeida 1922)
- Pseudoscada Godman & Salvin 1879 ( = Languida d’Almeida 1922)