Fiery red moth from Central America finally gains a scientific name

A moth with rusty, fiery red wings that has fluttered under the radar of formal science for decades — while quietly building a devoted following on the community-science platform iNaturalist — has at last been given a name. In a new taxonomic study, researchers Ryan St Laurent and Daniel Herbin describe Flammopenna, a new genus of sack-bearer moth, along with its single named species, Flammopenna maya. The animal belongs to the family Mimallonidae, a group of moths endemic to the Americas, and to the tribe Alheitini within the subfamily Lacosominae.

What makes the description remarkable is not just the moth's striking appearance, but its geography: Flammopenna is the only genus of alheitine moths endemic to Mexico and Central America, and the most northerly distributed member of its entire tribe. For a lineage whose species are overwhelmingly restricted to South America, this ruddy Central American outlier represents a genuine biogeographic puzzle now formally on the books. The description caps a broader effort to bring order to one of the most historically poorly studied families of American moths.

Recent phylogenomic work — studies that use genome-scale data to reconstruct evolutionary relationships — revised the higher classification of Mimallonidae and resulted in nearly all described species being assigned to monophyletic, thoroughly diagnosed genera, meaning groups that each contain an ancestor and all of its descendants. Two lineages, however, were left formally undescribed: one in the subfamily Mimalloninae and one in the lacosomine tribe Alheitini. The new study resolves the latter, placing Flammopenna on firm taxonomic footing.

The authors note that the moth has long been known to them, but formal description was required so that this organism could be properly identified and recorded by the scientific and naturalist communities alike — a need made urgent by the steady stream of iNaturalist observations accumulating over the past six years. Flammopenna is, by the authors' own diagnosis, unmistakable among Alheitini and among Lacosominae more broadly. Its subdued, ruddy, earthen tones, poorly delimited antemedial, medial, and submarginal wing zones, and wavy antemedial and postmedial lines with a faint apical lunule are, in combination, not observed in any other Mimallonidae.

Curiously, the moth appears more similar to members of a different subfamily, Cicinninae — genera such as Cicinnus or Aceclostria — than to any other member of its own tribe. That deceptive external appearance makes the genitalia all the more important for identification. Male genitalia are notably simple for an alheitine, defined by smoothly curving valvae, a fist-like gnathos, and a narrowly truncate uncus, with a pair of densely setose pads on the anellus below the vinculum.

The phallus tells perhaps the most dramatic evolutionary story. In Flammopenna it is nondescript but very narrow — unlike the typically broad or otherwise highly modified phallus of other Alheitini. The contrast with its sister genus Arianula is stark: that poorly known South American genus bears a comparatively massive, complex hammerhead-like phallus, and is very dissimilar to Flammopenna in both external and genitalia morphology.

Female genitalia are likewise notably simple for an alheitine, with the setose, bilobed plate of the lamella postvaginalis being the noteworthy character. In both genitalia preparations examined, the seemingly extremely fragile and thinly membraned corpus bursae — the bag-like reproductive structure that rarely contains complex diagnostic features in mimallonids — was not recovered. The physical description of the moth is detailed in the study.

Males have very large eyes occupying more than two-thirds of the area of the head, typical of Mimallonidae, and almost entirely bipectinate antennae with the distalmost six or seven antennomers dentate. Forewing length in males ranges from 14.0 to 15.0 millimeters, averaging 14.7 millimeters across 22 specimens; the triangular forewings are deeply concave below the apex and convex along the tornus, with a ground color of deep red-brown to paler rusty brown sprinkled with dark-brown spatulate scales. Females are somewhat broader-winged with shorter antennal pectinations, averaging 17 millimeters in forewing length across four specimens — sexual dimorphism is very limited.

The species name maya refers to the Mayan civilization of Central America, from where the genus is best represented in natural history museums, while Flammopenna is a feminine Latin construct of flammeus, meaning fiery red, and penna, meaning feather or wing, referring to the rusty to fiery red wings. The type series is substantial: a holotype male from Santa Rosa National Park in Costa Rica's Guanacaste province, collected in September 2009 at 265 meters elevation, plus 46 male and 8 female paratypes spanning Mexico, Guatemala, Nicaragua, and Costa Rica. Mexican material comes from Oaxaca, Guatemalan specimens from the departments of Zacapa and Huehuetenango, and Nicaraguan females from Laguna de Xiloa in Managua.

The densest representation, however, is Costa Rican: dozens of specimens from Guanacaste, many drawn from light-trap collections and rearing records in and around Santa Rosa National Park. Examined material derives from eight institutional collections across France, the United States, Canada, Costa Rica, Germany, and Guatemala, with dissections performed following established methodology and distribution mapping generated with SimpleMappr. What elevates this description from routine taxonomy to something approaching a community-science success story is the role of iNaturalist.

Over the past six years, observers have regularly recorded the new genus and species from a wide range of localities, despite its rarity in collections from locations other than Costa Rica. The study formally incorporates these photographic records, from Sinaloa, Jalisco, and Veracruz in Mexico, to El Zamorano in Honduras, to multiple sites in Guanacaste, Costa Rica — each credited to the iNaturalist user who made the observation. All records for the genus are from Central America, from as far north as Sinaloa on both Pacific and Atlantic coasts of Mexico, southward to northwestern Costa Rica.

The records are spotty across this region, and the moth's absence from most natural history collections — with no records before the 1970s — suggests it is rarely seen and likely more widely distributed than the few records would suggest. The natural history of Flammopenna contains one genuinely remarkable finding. Apart from habitats inferred from collecting data, the only other natural history data available comes from the rearing efforts of Janzen and Hallwach in Costa Rica.

Based on several records, they report the genus to feed on Diospyros acapulcensis, a plant in the family Ebenaceae — a rather remarkable host plant for Mimallonidae, which are otherwise not known to feed on this family of plants. The rearing database also contains a single record of the new genus from Eugenia acapulcensis in the Myrtaceae, but the authors could not find any other records to support this, and the shared specific epithet with the Diospyros species suggests it could be in error. Even so, Myrtaceae is one of the most common host plant families used by Mimallonidae.

No photos of the larvae are known, leaving the immature stages of this newly named moth essentially undocumented. Phylogenomic data place Flammopenna in a fascinating evolutionary context. In the earlier genome-scale study, the genus — then unnamed — was recovered with maximum support as sister to Arianula, a South American genus very dissimilar in both external and genitalia morphology.

Flammopenna was represented by a particularly long branch in that study, suggesting significant divergence from its sister. A later study estimated the divergence time between Arianula and Flammopenna at approximately 11.6 million years, meaning these two lineages have been evolving independently since roughly the middle Miocene. That deep split, combined with the dramatic differences in phallus structure between the two genera, paints a picture of a Central American lineage that has quietly charted its own morphological course for millions of years while its South American sister followed a very different one.

The study closes with a tantalizing hint of hidden diversity. The authors currently attribute all specimens to a single species, but the broad range, the lack of continuous records across that range, and minor base pair differences in the mitochondrial barcoding gene cytochrome c oxidase subunit I in publicly available molecular data are at least suggestive that cryptic diversity exists within the genus. The Costa Rican rearing efforts provide examples of two Barcode Index Numbers — genetically distinct clusters — from the same sites but without morphological differences, and two Costa Rican specimens outside the type series belong to a different BIN from other Costa Rican material.

Further collecting along the moth's entire range from Mexico to Central America and, ideally, population-level genomics would be useful to best understand its genetic diversity. For now, a fiery red moth that naturalists have been photographing for years finally has a name — and science has a new window into eleven million years of independent evolution.

Subject of Research: Taxonomic description of a new genus and species of sack-bearer moth (Mimallonidae, Alheitini) from Central America

Article Title: A new genus of Alheitini ( Lepidoptera , Mimallonidae , Lacosominae ) from Central America

Article References: St Laurent, R. A., Herbin, D., Janzen, D., & Hallwachs, W. (2026). A new genus of Alheitini (Lepidoptera, Mimallonidae, Lacosominae) from Central America. ZooKeys, 1295, 293-302. https://doi.org/10.3897/zookeys.1295.185731

Image Credits: AI Generated

DOI: 10.3897/zookeys.1295.185731

Keywords: Mimallonidae, Flammopenna, new genus, new species, taxonomy, Central America, iNaturalist, phylogenomics, Lepidoptera, Alheitini, Lacosominae, entomology