Glossata

Dyseriocrania subpurpurella, photographed by Sander van der Molen.

Belongs within: Lepidoptera.
Contains: Heteroneura, Exoporia.

The Glossata are the clade of Lepidoptera in which the mouthparts have become modified into a long coiled proboscis (though this has been lost in various subgroups). The proboscis also bears intrinsic musculature conveying greater mobility in members of the Neopseustidae, Exoporia and Heteroneura though such musculature is absent in Lophocorona, Acanthopteroctetes and Eriocraniidae. At least the upper layer of scales on the wing is hollow in most Glossata but only solid scales are present in Eriocraniidae (Nielsen & Common 1991). Basal lineages of the Glossata are mostly leaf-miners as larvae (Grimaldi & Engel 2005).

Moths with tongues
Published 25 August 2022

Two characters are commonly regarded as typical of the Lepidoptera, the moths and butterflies. The wings are densely covered by flattened scales, and the adult mouthparts are modified into a flexible proboscis. Scales are universal within the order and are, indeed, the source of the order’s name. The proboscis, however, is not. The earliest lepidopterans retained functional mandibles and a handful of mandibulate families survive to the modern day. The vast majority of modern lepidopterans, nevertheless, belong to the proboscis-bearing clade Glossata.

Glossatan mouthparts, showing the paired structure of the proboscis, from Grimaldi & Engel (2005).

The lepidopteran proboscis is formed from extended galeae, rod-like appendages of the maxillae, with rows of minute projections on the inner margins zipping the two galeae together (Grimaldi & Engel 2005). There are no functional mandibles in adult glossatans though their vestigial remnants may be present in some basal forms. Glossatans are also united by the presence in larvae of spinnerets alongside the mouth, used in the production of silk.

The majority of living Glossata can further be placed in the clades Exoporia and Heteroneura. In both these clades, the pupal stage of the life cycle is completely immobile. However, there are a small number of living species (about fifty all up, currently divided between five families) in which the pupa retains mobility in at least some of the segments of the abdomen, and also bears large, movable mandibles. All members of these basal families are tiny, typically with wingspans of less than a centimetre. Where known, their larvae that feed internally on vegetation, as leaf miners or in young shoots, and females have a piercing tip on the abdomen, the oviscapt, that is used in egg-laying. The large mandibles of the pupa are used to escape from its cell within the host tissue before moulting to adulthood.

Acanthopteroctetes unifascia, from the Denver Museum of Nature and Science Zoology.

The largest of the basal glossatan families is the Eriocraniidae, about thirty species of miners in Rosales and Fagales of the Holarctic realm. The Acanthopteroctetidae include five species known from western North America and the Crimea and are notable for the extreme narrowness of their wings. The fourteen species of Neopseustidae are known from eastern Asia and southern South America. The remaining two families are known only from southern Australia and include the six species of Lophocorona and the recently described Aenigmatinea glatzella. The immature stages of Neopseustidae and Lophocorona have not yet been identified but females have a similar oviscapt to other families, indicating a similar biology. Aenigmatinea glatzella is exceptional among glossatan moths in that its larvae feed on a conifer, the Australian native cypress Callitris gracilis. Though adults have vestigial mouthparts lacking a proboscis, their position in Glossata is well supported by other characters (Kristensen et al. 2015).

Aenigmatinea glatzella, from Kristensen et al. (2015).

Nielsen & Kristensen (1996) proposed a phylogenetic framework for these basal glossatan families (minus the not-yet-discovered Aenigmatinea, of course) that placed them as a series of progressively closer outgroups to the immobile-pupa clade of Exoporia and Heteroneura. Eriocraniidae was the most basal due to its retention of primitive solid wing-scales rather than the hollow scales of other Glossata. Neopseustidae formed a clade with Exoporia and Heteroneura owing to the presence of intrinsic muscles within the proboscis, allowing more complex control of its movements. However, recent molecular phylogenies have not supported this scenario (Kawahara et al. 2019; Kristensen et al. 2015). Instead, strong support has been found for a clade of Neopseustidae, Acanthopteroctetidae and Aenigmatinea, and for a sister relationship between Lophocorona and Exoporia. Eriocraniidae have also not been supported as the basalmost glossatans. The implication is that, for each of the characters regarded as critical in basal glossatan phylogeny (hollow wing-scales, intrinsic proboscis musculature, immobile pupae), their evolution has been more complex than previously thought. Either these features have each evolved on more than one occasion or they have been secondarily lost following their appearance. It is worth remembering that early divergence does not automatically correspond to primitive characteristics.

Systematics of Glossata

Synapomorphies (from Grimaldi & Engel 2005): Nonfunctional or vestigial adult mandibles, lacinia reduced; galeae long, concave and zippped together with rows of minute processes (legulae) to form a proboscis that is usually coiled at rest; larva with a spinneret on apex of prelabial-hypopharyngeal lobe.

<==Glossata [Coelolepida, Eriocraniina, Eriocranioidea, Haustellata, Myoglossata]
    |  i. s.: CatapterigidaeNC91
    |--Neolepidoptera [Monotrysia]GE05
    |    |--HeteroneuraKP19
    |    `--+--ExoporiaKP19
    |       `--Lophocorona [Lophocoronidae, Lophocoronina, Lophocoronoidea]KP19
    |            |--L. astipicaKP19
    |            |--L. melanoraNC91
    |            `--L. pediasiaNC91
    `--+--NeopseustoideaKP19
       |    |--Acanthopteroctetes [Acanthopteroctetidae, Acanthopteroctetoidea]KP19
       |    |    `--A. unifasciaKP19
       |    `--+--Neopseustidae [Neopseustina]KH15
       |       |    |--Apoplania valdivianaWRM02
       |       |    |--Neopseustis meyrickiKP19
       |       |    `--Archepiolus schmidi Mutuura 1971KH15
       |       `--Aenigmatinea Kristensen, Hilton et al. 2015 [Aenigmatineidae]KH15
       |            `--*A. glatzella Kristensen, Hilton et al. 2015KH15
       `--EriocraniidaeGE05
            |  i. s.: MnemonicaRD77
            |           |--M. auricyaneaP27
            |           `--M. subpurpurellaRD77
            |         Electrocrania immensipalpa Kuznetsov 1941P92
            |--DyseriocraniaKP19
            |    |--D. auricyaneaWRM02
            |    |--D. griseocapitellaWRM02
            |    |--D. perveta Cockerell 1919P92
            |    `--D. subpurpurellaWRM02
            `--+--Heringocrania unimaculellaWRM02
               `--EriocraniaWRM02
                    |--E. sangiiWRM02
                    `--E. semipurpurellaWRM02

*Type species of generic name indicated

References

[GE05] Grimaldi, D., & M. S. Engel. 2005. Evolution of the Insects. Cambridge University Press: New York.

[KP19] Kawahara, A. Y., D. Plotkin, M. Espeland, K. Meusemann, E. F. A. Toussaint, A. Donath, F. Gimnich, P. B. Frandsen, A. Zwick, M. dos Reis, J. R. Barber, R. S. Peters, S. Liu, X. Zhou, C. Mayer, L. Podsiadlowski, C. Storer, J. E. Yack, B. Misof & J. W. Breinholt. 2019. Phylogenomics reveals the evolutionary timing and pattern of butterflies and moths. Proceedings of the National Academy of Sciences of the USA 116 (45): 22657–22663.

[KH15] Kristensen, N. P., D. J. Hilton, A. Kallies, L. Milla, J. Rota, N. Wahlberg, S. A. Wilcox, R. V. Glatz, D. A. Young, G. Cocking, T. Edwards, G. W. Gibbs & M. Halsey. 2015. A new extant family of primitive moths from Kangaroo Island, Australia, and its significance for understanding early Lepidoptera evolution. Systematic Entomology 40: 5–16.

[NC91] Nielsen, E. S., & I. F. B. Common. 1991. Lepidoptera (moths and butterflies). In: CSIRO. The Insects of Australia: A textbook for students and research workers 2nd ed. vol. 2 pp. 817–915. Melbourne University Press: Carlton (Victoria).

Nielsen, E. S., & N. P. Kristensen. 1996. The Australian moth family Lophocoronidae and the basal phylogeny of the Lepidoptera-Glossata. Invertebrate Taxonomy 10: 1199–1302.

[P27] Philpott, A. 1927. The maxillae in the Lepidoptera. Transactions and Proceedings of the New Zealand Institute 57: 721–746.

[P92] Poinar, G. O., Jr. 1992. Life in Amber. Stanford University Press: Stanford.

[RD77] Richards, O. W., & R. G. Davies. 1977. Imms’ General Textbook of Entomology 10th ed. vol. 2. Classification and Biology. Chapman and Hall: London.

[WRM02] Wiegmann, B. M., J. C. Regier & C. Mitter. 2002. Combined molecular and morphological evidence on the phylogeny of the earliest lepidopteran lineages. Zoologica Scripta 31 (1): 67–81.

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