Fore wing of Permithone belmontensis, from Kukalová-Peck (1991).

Belongs within: Holometabola.
Contains: Raphidioptera, Megaloptera, Coniopterygidae, Euneuroptera.

The Neuropterida are a clade of largely predatory insects whose wings are often densely veined. Members are united by possession of a medially divided metapostnotum, the first abdominal tergum having a caudally bifid longitudinal sulcus, the fusion of the gonoplacs in the ovipositor, and a proventriculus with an unpaired diverticulum (Grimaldi & Engel 2005).

Modern Neuropterida have been divided between three orders, the Raphidioptera, Megaloptera and Neuroptera. The Neuroptera, lacewings, are characterised by having the ninth gonocoxites associated with the gonarcus, and larvae with sucking mouthparts in which the maxillae and mandibles form a tube (Grimaldi & Engel 2005). Relationships between the three orders have been subject to debate but Megaloptera and Neuroptera may be united in a clade Eidoneuroptera by the integration of the larval cardines into the head capsule and the structure of the male genitalia. Characters shared between Megaloptera and Raphidioptera such as chewing mandibles in the larvae and exarate (mobile) pupae are likely to be plesiomorphies of the clade as a whole.

Potential fossil representatives of the Neuropterida include the Permian–Jurassic Glosselytrodea, generally small insects with subequal pairs of wings bearing numerous crossveins. The fore wings were tegminous and possessed an expanded precostal area forming a prominent bulge at the wing base. Body fossils are few but indicate a hypognathous head, slender legs and short cerci (Grimaldi & Engel 2005). The Protoneuroptera, including the Permithonidae and Permoberotha, may represent stem-representatives of the Eidoneuroptera and/or Neuroptera alone (Engel et al. 2018). Permoberotha resembles Glosselytrodea in the presence of relatively straight, subparallel MA and MP veins, and a relatively straight CuP vein followed by crowded anal veins (Grimaldi & Engel 2005). The Permian Parasialidae and Nanosialidae may be indicated as stem-Raphidioptera by the presence of a distinct pterostigma and a shared, subproximal fusion of M and CuA (Engel et al. 2018).

Snakes and lace
Published 19 December 2020

The holometabolous insects—that is, the clade containing most insects with a complex life cycle including differentiated larval and pupal stages—is one of the most extensive radiations of animals on this planet. Much of this diversity is assigned to four major orders: wasps, moths, beetles and flies. But there are also a number of smaller lineages making up the holometabolous insects. Among these are the lacewings and their relatives in the clade Neuropterida.

Female snakefly Puncha ratzeburgi, copyright Hectonichus.

Modern members of the Neuropterida are generally recognised as belonging to three orders—the lacewings and ant-lions in the Neuroptera, the snakeflies in the Raphidioptera, and the alderflies and dobsonflies in the Megaloptera—though go back a few decades and you may find texts referring to a single order Neuroptera. A number of authors have advocated for use of the name ‘Planipennia’ for the lacewing order to avoid confusion with the broader sense of Neuroptera but, while a case could certainly be made for this usage, it’s just never really caught on. Most neuropteridans are fairly similar in overall appearance: long-bodied insects with well developed wings with numerous crossveins. Of the living holometabolous insects, they probably bear the greatest overall resemblance to the clade’s ancestors and hence they are commonly thought of as ‘relicts’. However, they do possess their own specialisations and are not primitive in every regard (for instance, the most primitive egg-laying apparatus among holometabolous insects belong to wasps). Species of Neuropterida are mostly predators as larvae. The larvae of the lacewing family Ithonidae may possibly feed on decaying plant matter though we don’t know for certain (Grimaldi & Engel 2005). Adults are predators and/or pollen-feeders, or may not feed at all in some short-lived forms.

Male (above) and female dobsonflies Corydalus cornutus, copyright Didier Descouens.

The exact relationships between the neuropteridan orders have been debated over the years. Though most of their obvious similaities to each other represent shared ancestral features, there is a broad consensus that they do indeed form a clade. There has also been little, if any, question of the monophyly of the Raphidioptera and Neuroptera; the monophyly of Megaloptera has been more debated but seems more likely than not. Most recent studies have suggested that the Raphidioptera are the sister group to a clade of the other two orders (Engel et al. 2018). Raphidioptera are the least diverse of the generally recognised living orders of insects with about 250 known species. They are found in cooler regions of the Northern Hemisphere—in the temperate zone or at higher elevations in lower latitudes—and are completely absent from the Southern Hemisphere (Aspöck & Aspöck, 1991, refer to a failed attempt to introduce them to Australia and New Zealand but provide no details why such a thing was tried in the first place). They are characterised by a notably elongate prothorax (the first segment of the thorax) which explains the vernacular name of ‘snakefly’. Larvae live under bark or in litter and moult into pupae with the onset of cold weather. The pupae of Raphidioptera and Megaloptera are primitive in aspect, with legs separate from the body wall, and are highly mobile. Engel et al. (2018) even refer to the pupae of Raphidioptera as ‘active predators’ but I’ve not been able to find corroborating details for that remarkable description.

The Megaloptera are often particularly large neuropteridans, reaching up to twenty centimetres in wingspan, and comprise a bit less than 400 species worldwide, mostly found in temperate regions. Larvae are aquatic, living under rocks and debris, and characterised by the presence of filamentous lateral gills on the abdomen. Adults are short-lived and feed little if at all. Male dobsonflies (of the subfamily Corydalinae) possess spectacularly large, curved mandibles of largely unknown purpose; certainly they do not seem to use them for biting.

Mantisfly Mantispa styriaca, a raptorial lacewing, copyright Gilles San Martin.

The largest of the three orders, by a considerable margin, is the Neuroptera with over 5700 known species. Needless to say, this level of species diversity is associated with a high diversity of appearances and lifestyles, too many to cover adequately here. The larvae of two families of Neuroptera, the Nevrorthidae and Sisyridae, are aquatic and there has been a long-running debate whether this aquatic habit is an ancestral feature of the order shared with the Megaloptera (Nevrorthidae larvae are generalist predators, Sisyridae are specialised feeders on freshwater sponges and bryozoans). However, recent phylogenetic studies (e.g. Vasilikopoulos et al. 2020) do not agree with earlier hypotheses that the Nevrorthidae represent the sister taxon of the remaining Neuroptera. Instead, Nevrorthidae and Sisyridae may form a clade with the Osmylidae, a family whose larvae are not aquatic but often inhabit damp stream banks. The aquatic Neuroptera probably entered the water independently of the alderflies. The current favourites for the sister clade of other neuropterans are the dustywings of the Coniopterygidae, a group of small neuropterans with reduced wing venation that have historically been difficult to place owing to their derived features.

An unidentified dustywing, Coniopterygidae, copyright Katja Schulz.

A fourth order has often been associated with the Neuropterida, the extinct Glosselytrodea. Glosselytrodeans are small insects known from the Late Permian to the Jurassic, characterised by wings bearing dense cross-veins of which the fore pair would have had a leathery appearance in life (not dissimilar in texture to the fore wings of grasshoppers and other Orthoptera). Other than the wings, the features of glosselytrodeans are poorly known: they seem to have been hypognathous (i.e. had the head directed downwards) with slender legs (Grimaldi & Engel 2005). Connections to Neuropterida are based on features of the wing venation but cannot be considered strongly supported. Other authors have regarded them as of uncertain position within the broader holometabolous clade, or even as more closely related to the Orthoptera than any Holometabola. Unless more complete remains should come to light, it seems likely that the question will remain open.

Systematics of Neuropterida
<==Neuropterida [Hemerobini, Myrmeleontidea, Neuropteroidea]GE05
| i. s.: Ororaphidia megalocephalaWHW10
|--Glosselytrodea [Jurinida]GE05
| |--ArchoglossopterumR02 [ArchoglossopteridaeGE05]
| |--UskatelytrumR02 [UskatelytridaeGE05]
| |--MongolojurinaRJ93 [PolycytellidaeGE05]
| | `--M. altaica Ponomarenko 1988RJ93
| |--GlosselytronR02 [GlosselytridaeGE05]
| | `--G. martynovaeR02
| |--GlossopterumR02 [GlossopteridaeGE05]
| | `--G. martynovaeR02
| `--JurinidaeGE05
| |--Jurina marginataGE05
| `--EoglosselytrumKN13
| |--E. perfectumR02
| `--E. perplexa (Riek 1953)KN13
| | |--Parasialis latipennisMW15, P02
| | `--SonjanasialisMW15
| `--+--NanosialidaeEWB18
| `--RaphidiopteraGE05
| |--PermoberothaGE05 [PermoberothidaeEWB18]
| | `--P. villosaGE05
| `--Permithonidae [Permopsychopidae]EWB18
| |--Sylvasenex lacrimabundusP02
| |--Permithonopsis enormisP02
| |--Permosisyra paurovenosaP02
| |--Permopsychops belmontensis Tillyard 1926 [incl. Permithone venosa Davis 1943]F71
| |--Permipsythone panfiloviRJ93
| |--Tschekardithonopsis obliviusB11
| `--PermithoneK-P91
| |--P. belmontensis Tillyard 1922 [incl. Permosmylus pincombeae Tillyard 1926]F71
| |--P. neoxenus Riek 1953F71
| `--P. oliarcoides Tillyard 1926F71
`--Neuroptera [Euneuropteroidea, Hemerobiiformia, Myrmeleontida, Planipennia]GE05
| i. s.: MesopolystoechotidaeREL02
| |--Mesopolystoechus Martynov 1937REL02
| `--Megapolystoechus magnificusRJ93
| Archegetes neuropterumW13
| Megapolystoechotes Tillyard 1933REL02
| Cratosisyrops gongazai Martins-Neto 1997NM03
| GrammosmylidaeGE05
| Sialidopsis [Sialidopsidae]R70
| `--S. kargalensisR70
| PalaemerobiidaeRJ93
| Vatiga illudensM99
| ChrysoleonitesP02

*Type species of generic name indicated


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[B11] Bashkuev, A. S. 2011. Nedubroviidae, a new family of Mecoptera: the first Paleozoic long-proboscid scorpionflies. Zootaxa 2895: 47–57.

[EWB18] Engel, M. S., S. L. Winterton & L. C. V. Breitkreuz. 2018. Phylogeny and evolution of Neuropterida: where have wings of lace taken us? Annual Review of Entomology 63: 531–551.

[F71] Fletcher, H. O. 1971. Catalogue of type specimens of fossils in the Australian Museum, Sydney. Australian Museum Memoir 13: 1–167.

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[KN13] Kirejtshuk, A. G. & A. Nel. 2013. Skleroptera, a new order of holometabolous insects (Insecta) from the Carboniferous. Zoosystematica Rossica 22 (2): 247–257.

[K-P91] Kukalová-Peck, J. 1991. Fossil history and the evolution of hexapod structures. In: CSIRO. The Insects of Australia: A textbook for students and research workers vol. 1 pp. 141–179. Melbourne University Press: Carlton (Victoria).

[MW15] McKenna, D. D., A. L. Wild, K. Kanda, C. L. Bellamy, R. G. Beutel, M. S. Caterino, C. W. Farnum, D. C. Hawks, M. A. Ivie, M. L. Jameson, R. A. B. Leschen, A. E. Marvaldi, J. V. McHugh, A. F. Newton, J. A. Robertson, M. K. Thayer, M. F. Whiting, J. F. Lawrence, A. Ślipiński, D. R. Maddison & B. D. Farrell. 2015. The beetle tree of life reveals that Coleoptera survived end-Permian mass extinction to diversify during the Cretaceous terrestrial revolution. Systematic Entomology 40 (4): 835–880.

[M99] Moraes, G. J. de. 1999. Pest status of the cassava green mite in Brazil and strategies for its control. In: Needham, G. R., R. Mitchell, D. J. Horn & W. C. Welbourn (eds) Acarology IX vol. 2. Symposia pp. 287–291. Ohio Biological Survey: Columbus (Ohio).

[NM03] Nel, A., J.-J. Menier, A. Waller, G. Hodebert & G. de Ploëg. 2003. New fossil spongilla-flies from the lowermost Eocene amber of France (Insecta, Neuroptera, Sisyridae). Geodiversitas 25 (1): 109–117.

[P02] Ponomarenko, A. G. 2002. Superorder Myrmeleontidea Latreille, 1802 (=Neuropteroidea Handlirsch, 1903). In: Rasnitsyn, A. P., & D. L. J. Quicke (eds) History of Insects pp. 176–189. Kluwer Academic Publishers: Dordrecht.

[R02] Rasnitsyn, A. P. 2002. Order Jurinida M. Zalessky, 1928 (=Glosselytrodea Martynov, 1938). In: Rasnitsyn, A. P., & D. L. J. Quicke (eds) History of Insects pp. 189–192. Kluwer Academic Publishers: Dordrecht.

[REL02] Ren, D., M. S. Engel & W. Lü. 2002. New giant lacewings from the Middle Jurassic of Inner Mongolia, China (Neuroptera: Polystoechotidae). Journal of the Kansas Entomological Society 75 (3): 188–193.

[R70] Riek, E. F. 1970. Fossil history. In: CSIRO. The Insects of Australia: A textbook for students and research workers pp. 168–186. Melbourne University Press.

[RJ93] Ross, A. J., & E. A. Jarzembowski. 1993. Arthropoda (Hexapoda; Insecta). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 363–426. Chapman & Hall: London.

Vasilikopoulos, A., B. Misof, K. Meusemann, D. Lieberz, T. Flouri, R. G. Beutel, O. Niehuis, T. Wappler, J. Rust, R. S. Peters, A. Donath, L. Podsiadlowski, C. Mayer, D. Bartel, A. Böhm, S. Liu, P. Kapli, C. Greve, J. E. Jepson, X. Liu, X. Zhou, H. Aspöck & U. Aspöck. 2020. An integrative phylogenomic approach to elucidate the evolutionary history and divergence times of Neuropterida (Insecta: Holometabola). BMC Evolutionary Biology 20: 64.

[WHW10] Winterton, S. L., N. B. Hardy & B. M. Wiegmann. 2010. On wings of lace: phylogeny and Bayesian divergence time estimates of Neuropterida (Insecta) based on morphological and molecular data. Systematic Entomology 35: 349–378.

[W13] Witton, M. P. 2013. Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press: Princeton (New Jersey).

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