Beetles That Time Forgot

J. B. S. Haldane once apocryphally quipped that if there was one thing that could be surmised about any Supreme Deity from available scientific evidence, it was that said Deity possessed an inordinate fondness for beetles (Hutchinson, 1959). This deduction may be understated, as it has been estimated that the order Coleoptera includes somewhere in the neighborhood of a million species (about 2/5 of which have been described as of yet; Foottit & Adler, 2009). 

Tenomerga cinerea (Cupedidae; photographed by ophis)

This profusion of beetles is subdivided into a quartet of suborders: two (Polyphaga and Adephaga) are speciose; the remainder—Myxophaga and Archostemata—not so much. Archostematans are especially depauperate in terms of diversity: only 42 extant species in 5 families are known (Hörnschemeyer, 2011), which as a whole range from uncommon (Crowson, 1962) to vanishingly rare (the family Crowsoniellidae is known from a single series of specimens; Pace, 1975).  Even a person such as myself, who has encountered his share of rare insects, has only happened upon an archostematan once (the cupedid species shown above).

Live Tetraphalerus bruchi (Ommatidae) photographed by Adriana Marvaldi

Indeed, the Archostemata are far more abundant as fossils than as living beetles. To draw an example from the taxonomic hat, the Ommatidae are currently represented by the genera Omma (with 4 spp. restricted to Australia) and Tetraphalerus (2 spp. restricted to central South America; Beutel et al., 2008): whereas their fossil record (extending back to the early Triassic Period) includes specimens from throughout Eurasia, totaling around 100 species (Tan et al., 2012). The pre-Cenozoic archostematan breadth of morphoecology is congruently impressive: many of the Permian-to-Jurassic Schizophoridae possessed a longitudinal groove delineated along their abdominal margin into which their elytra locked (Rohdendorf et al., 1961), an adaptation indicating an aquatic lifestyle (being moreover herbivorous or carnivorous; Ponomarenko, 2003); other schizophoroids were long-legged dashers in the carabid milieu (Tan et al., 2013) or (in the case of Tricoleidae) bore reticulated, tuberculate elytra: as these are a feature of modern Ommatidae and Cupedidae (the extant Cupedomorpha; Lawrence, 1999), it can be surmised that tricoleid biology was as it is among the modern cupedomorphs—one of dwelling within and feeding upon decayed wood. It has even been speculated that some prehistoric cupedomorphs may have been carnivorous (Jing-Jing et al., 2006), deviating from their contemporary xylomycetophagous norm.

Depiction of tshekardocoleid Sylvacoleus sharovi

Although their present diversity is poor by comparison to its past glory, the disparity of the extant Archostemata is in all fairness not to be sneezed at. Indeed, they are various (even absent the Myxophaga; these were placed within the Archostemata by Ponomarenko, 2002 and Kirejtshuk et al., 2013) to such a degree that the monophyly of the group as presently constituted has been debatable (yet affirmed by multiple studies; Beutel et al., 2008; Hörnschemeyer, 2009; Ge et al., 2010). The suborder was originally defined as restricted to what is now the infraorder Cupedomorpha (Kolbe, 1908): consequently, these are more or less regarded as the archetypal archostematans. Their retention of rib-demarcated elytral cells (vestiges of the veins present in the ancestral beetle's forewings-turned-elytra), shared with the most primeval families of Coleoptera (such as the Tshekardocoleidae: these include what is at c. 298-293 million years old the most ancient of all beetles; Gradstein et al., 2012; Kirejtshuk et al., 2013), is what has earned the Archostemata a reputation as the most primitive of the beetle suborders (although Tshekardocoleidae et al. are phylogenetically exterior to all coleopteran suborders; Beutel et al., 2008). Yet despite their seemingly archaic adult habitus, ommatid and cupedid larval morphology is specialized to such a degree as to resemble unrelated fellow wood-borers among the Polyphaga (Beutel & Hörnschemeyer, 2002a).

We praise thee, Alex Wild, for thy likeness of M. debilis herewith presented

The remainder of the Archostemata lack the many features that distinguish the Cupedomorpha (among them window-puncture-bearing elytra, transverse mesothoracic ridge, and exposed metatrochantin; Frank et al., 2009): the monotypic (although an additional species is possible; Marshall & Thornton, 1963) Micromalthidae are true to all this; and what with their smooth, shortened elytra and length of only a few millimeters, they bear not the slightest resemblance to cupedomorphs. Micromalthus debilis was repeatedly placed within the Polyphaga, whether of proposed cantharoid (Arnett, 1968) or lymexyloid affinity (Jeannel & Paulian, 1949; Barlet, 1996), or within the Lymexylidae itself (LeConte, 1878; Hubbard, 1878): their archostematan affinity is now certain (Beutel & Hörnschemeyer, 2002b). "Telephone-pole beetles" make their paleontological debut only in the Cretaceous Period (Crowson, 1981) (all specimens from prehistoric eons representing the single extant species; Hörnschemeyer et al., 2010), although their fragility and diminution would largely preclude their fossilization regardless of the family's age. A few of these amber-preserved fossils hail from well beyond telephone-pole beetles' modern North American range (Crowson, 1981; Lawrence, 1991; Lawrence & Newton, 1995).

Well, it still makes more sense than some college class flowcharts I've seen...

But the most interesting aspect of M. debilis would be its ontogeny, to which multitudes of coleopterists have attached all manner of superlatives: I'll just say here that God gives all appearances of having been stoned off His bum when He created the telephone-pole beetle. The exceedingly confusing life cycle of this creature has been summarized in the flowchart shown at left, created by Heath Blackmon; according to him, it is most sensible to consider the tangled affair beginning with the triungulin larvae, which are universally female and conceived parthenogenetically: these moult into a cerambycoid larva in which the ovaries begin to mature, subsequently either undergoing pupation into adults or moulting into larvae with fully mature ovaries, enabling them to a) parthenogentically lay eggs which hatch into the aforementioned triungulins or b) arrhenotokously conceive eggs (Scott, 1938) which hatch into curculionoid male larvae (remaining attached to their mother until they do so), which mature fully into adult males that copulate with adult females, fathering triungulin daughters. I should note here that it is presumed that the adult M. debilis (which are scarce representatives of their species) reproduce sexually: some coleopterists have hypothesized that these males do not mate at all (Smith, 1971; White, 1973), and are thus in essence useless. This seems unlikely, since female reproductive larvae are penalized severely for bearing sons: males (always lone) hatch, invariably plunge into their mother, and, as Christopher Taylor put it, "eat mum from the inside out". Hence it makes little sense that males would be utterly without function (Pollock & Normark, 2002). 

Line drawing of Crowsoniella relicta (Pace, 1975)

In terms of their prolonged presence in the fossil record, telephone-pole beetles are undoubtedly antiquated: yet they are hardly archaic; nor are they alone in this state of specialization. The tiny Crowsoniella relicta lacks many of the same traits that are found in the remaining archostematans, but are absent from micromalthids—their metepisterna do not adjoin the metacoxal cavities, nor do they possess prothoracic sutures (Barlet, 1996; Kirejtshuk et al., 2010), bearing almost no apparent kinship to the ommatids among which this species was initially classified (Lawrence & Newton, 1982). Consequently, the Crowsoniellidae (just as were the similarly monotypic Micromalthidae) have been purported to belong in Polyphaga (Kirejtshuk et al., 2010). But since the argument for this position can be reduced to the following exchange—"How do you know this beetle is a polyphagan?" "It looks like one!" (Ge et al., 2010)—it holds little water. Of course, the fact that all C. relicta were collected in soil samples drawn from the base of a single Italian chestnut tree (and have never been collected since) means that its taxonomy must be guessed at without recourse to evidence from larval morphology, molecular genetics, or biological data; but on the basis of known characteristics, it appears that crowsoniellids are indeed derived archostematans (Crowson, 1975; Lawrence, 1982; Beutel et al., 2008; Hörnschemeyer, 2009). 

Holotype of Sikhotealinia zhiltzovae

So far, all the archostematans examined herein have failed to live up to their suborder's reputation as the most archaic within the Coleoptera; and the family with which I conclude (the Jurodidae) are not wholly dissimilar from them. They put one in mind of the crowsoniellids in terms of their exceptional rarity: the only extant species is known from but a single specimen (shown at left) collected in the Sikhote-Alin cordillera of Russia's Maritime Province (Lafer, 1996). They are, nevertheless, indubitably ancient: the Transbaikalian fossils from which they were first described potentially date to as old as ~175 m.y.a. (Gradstein et al., 2012).

Jurodids present a confusing mosaic of traits: their enlarged coxae suggested that they should be placed within the Adephaga (Ponomarenko, 1985); whilst the discovery of the extant S. zhiltzovae (and additional fossil remains of Jurodes) revealed features that indicated an archostematan identity (Kirejtshuk, 1999) along with wing venation resembling that of the polyphagan superfamilies Scirtoidea and Scarabaeoidea (Fedorenko, 2009). Comparisons were therefore even drawn to the Derodontidae (which were later demonstrated as superficial; Ge et al., 2007; Yan et al., 2014), leading to the outright placement of S. zhiltzovae in the Polyphaga (Lafer, 1996). Strangest of all, though, is their possession of an ocellar triad on the head (Yan et al., 2014). Ocelli are absent in all other beetles (Leschen & Beutel, 2004) with the exception of a teratological omaliine rove beetle (Staphylinidae) (Naomi, 1987): even the Tshekardocoleidae lacked these light-sensing ommatidia (Ponomarenko, 2002). As a result, Jurodidae have been placed as the sister-group to the remaining Archostemata (Hörnschemeyer, 2005; Beutel et al., 2008).

Considering this phylogeny, notable atavism, and the fact that the Jurodidae have hardly changed since the mid-Jurassic (Yan et al., 2013) we can rightfully call them beetles that time forgot.

                                                
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Arnett, R. H. (1968). The Beetles of the United States. Ann Arbor: American Entomological Institute.

Barlet, J. (1996). Quelques précisions au sujet de Micromalthus (Insecta Coleoptera). Bulletin de la Société Royale des Sciences de Liège, 65, 373-378.

Beutel, R. G. and Hörnschemeyer, T. (2002a). Description of the larva of Rhipsideigma raffrayi (Coleoptera, Archostemata), with phylogenetic and functional implications. European Journal of Entomology, 99, 53-66.

Beutel, R. G. and Hörnschemeyer, T. (2002b). Larval morphology and phylogenetic position of Micromalthus debilis LeConte (Coleoptera: Micromalthidae) [electronic version]. Systematic Entomology, 27, 169-190. Retrieved 8/31/14 from http://onlinelibrary.wiley.com/doi/10.1046/j.1365-3113.2002.00172.x/pdf 

Beutel, R. G.; Ge, S.-Q.; and Hörnschemeyer, T. (2008). On the head morphology of Tetraphalerus, the phylogeny of Archostemata and the basal branching events in Coleoptera. Cladistics, 24, 270-298. Retrieved 7/15/14 from http://www.researchgate.net/publication/229077348_On_the_head_morphology_of_Tetraphalerus_the_phylogeny_of_Archostemata_and_the_basal_branching_events_in_Coleoptera

Crowson, R. A. (1962). Observations on the beetle family Cupedidae, with the descriptions of two new fossil forms and a key to the recent genera. Annals of the Magazine of Natural History, 5, 147-157.

Crowson, R. A. (1975). The systematic position and implications of Crowsoniella. Bolletino del Museu Civico di Storia Naturale di Verona, 2, 459-463.

Crowson, R. A. (1981). The Biology of Coleoptera. London: Academic Press. 

Fedorenko, D. N. (2009). Evolution of the Beetle Hind Wing, with Special Reference to Folding (Insecta: Coleoptera). Sofia-Moscow: Pensoft Publishers.

Foottit, R. G. and Adler, P. H. (2009). Insect Biodiversity: Science and Society. Hoboken: Wiley-Blackwell.

Frank, F.; Farrell, B. D.; and Beutel, R. G. (2009). The thoracic morphology of Archostemata and the relationships of the extant suborders of Coleoptera (Hexapoda). Cladistics, 25(1), 1-37. Retrieved 8/6/14 from http://dash.harvard.edu/bitstream/handle/1/3114645/farrell_thoracicmorphology.pdf?sequence=1

Ge, S.-Q.; Beutel, R. G.; and Yang, X. K. (2007). Thoracic morphology of adults of Derodontidae and Nosodendridae and its phylogenetic implications (Coleoptera). Systematic Entomology, 32, 635-667.

Ge, S.-Q.; Hörnschemeyer, T.; Friedrich, F.; and Beutel, R. G. (2010). Is Crowsoniella relicta really a cucujiform beetle? Systematic Entomology, 36(1), 175-179. Retrieved 7/22/14 from http://www.researchgate.net/publication/229077093_Is_Crowsoniella_relicta_really_a_cucujiform_beetle 

Gradstein, F. M.; Ogg, J. G.; Schmitz, M.; and Ogg, G. (2012). A Geologic Time Scale 2012. Amsterdam: Elsevier B.V.

Hörnschemeyer, T. (2005). Archostemata Kolbe, 1908. In Kristensen, N. P. and Beutel, R. G. (eds.): Coleoptera, Vol. 1. Morphology and Systematics (Archostemata, Adephaga, Myxophaga, Polyphaga Partim). Handbook of Zoology Vol. IV, Arthropoda: Insecta (pp. 157-182). Berlin-New York: De Gruyter. 


Hörnschemeyer, T. (2009). The species level phylogeny of archostematan beetles—where do Micromalthus debilis and Crowsoniella relicta belong? Systematic Entomology, 34(3), 533-558. Retrieved 7/22/14 from http://www.readcube.com/articles/10.1111/j.1365-3113.2009.00476.x

Hörnschemeyer, T. Tree of Life: Archostemata. (27 March, 2011). Retrieved 8/7/14 from http://tolweb.org/Archostemata/8876 

Hörnschemeyer, T.; Wedmann, S. and Poinar, G. (2010). How long can insect species exist? Evidence from extant and fossil Micromalthus beetles (Insecta: Coleoptera) [electronic version]. Zoological Journal of the Linnean Society, 158, 300-311. Retrieved 8/814 from http://www.researchgate.net/publication/223131272_How_long_can_insect_species_exist_Evidence_from_extant_and_fossil_Micromalthus_beetles_%28Insecta_Coleoptera%29  
Hubbard, H. G. (1878). Description of the larva of Micromalthus debilis LeC. Proceedings of the American Philosophical Society, 17, 666-668.

Hutchinson, G. E. (1959). Homage to Santa Rosalia or Why are There So Many Kinds of Animals [electronic version]? The American Naturalist, 93(870), 145-159. Retrieved 7/16/14 from http://www.jstor.org/discover/10.2307/2458768?uid=3739680&uid=2&uid=4&uid=3739256&sid=21104341432977

Jeannel, R. and Paulian, R. (1949). Les coleóptères. Grassè, P-P. (ed.): Traité de Zoologie, 771-1,077. Paris: Masson.

Jing-Jing, T.; Ren, D.; and Chung-Kun, S. (2006). Palaeogeography, palaeoecology and taphonomy of Jurassic-Cretaceous Cupedomorpha faunas from China. Mesozoic Terrestrial Ecosystems, 130-133. Retrieved 7/17/14 from http://www.docstoc.com/docs/19891688/palaeogeography-palaeoecology-and-taphonomy-of-jurassic

Kolbe, H. (1908). Mein System der Coleopteren. Zeitschrift für Wissenschaftliche Insekten-Biologie, 4, 116-123, 153-162, 219-226, 246-251, 286-294, 389-400.

Kirejtshuk, A. G. (1999). Sikhotealinia zhiltzovae Lafer, 1996—recent representative of the Jurassic coleopterous fauna (Coleoptera, Archostemata, Jurodidae). Proceedings of the Zoological Institute RAS, 281, 21-26.

Kirejtshuk, A. G.; Nel, A.; and Collomb, F.-M. (2010). New Archostemata (Insecta: Coleoptera) from the French Paleocene and Early Eocene, with a note on the composition of the suborder. Annales de la Société Entomologique de France, (n.s.); 46, 216-227.

Kirejtshuk, A. G.; Poschmann, M.; Prokop, J.; Garrouste, R.; and Nel, A. (2013). Evolution of the elytral venation and structural adaptations in the oldest Paleozoic beetles (Insecta: Coleoptera: Tshekardocoleidae). Journal of Systematic Paleontology, 1-26. Retrieved 7/22/14 from http://www.researchgate.net/publication/258221814_Evolution_of_the_elytral_venation_and_structural_adaptations_in_the_oldest_Palaeozoic_beetles_%28Insecta_Coleoptera_Tshekardocoleidae%29 

Lafer, G. S. (1996). Family Sikhotealiniidae. In Ler, P. A. (ed.): Key to the Insects of the Russian Far East, vol. III, pt. 3 (pp. 390-396). Vladivostok: Dal'nauka. 

Lawrence, J. F. (1982). Coleoptera. Parker, S. (ed.): Synopsis and Classification of Living Organisms (pp. 482-553). New York: McGraw-Hill.

Lawrence, J. F. (1991). Ommatidae (=Ommadidae, including Tetraphaleridae), Cupedidae (Archostemata) (=Cupesidae), Micromalthidae (Archostemata), Buprestidae (Buprestoidea) (incl. Schizopodidae), Zopheridae (Tenebrionoidea) (including Merycidae). Cerambycidae (Chrysomeloidea) (including Disteniidae, Hypocephalidae, Oxypeltidae, Parandridae, Spondylidae, Vesperiidae). Stehr, F. W. (ed.): Immature Insects, vol. 2 (pp. 298-302, 386-388, 518-519, 556-561). Dubuque: Kendall/Hunt Publishing Co.

Lawrence, J. F. (1999). The Australian Ommatidae (Coleoptera: Archostemata): new species, larva and discussion of relationships. Invertebrate Taxonomy, 13, 369-390.

Lawrence, J. F. and Newton, A. F. (1982). Evolution and classification of beetles. Annual Review of Technology and Systematics, 13, 261-290.

Lawrence, J. F. and Newton, A. F. (1995). Families and subfamilies of Coleoptera. In Pakaluk, J. and Slipinski, S. A. (eds.): Biology, Phylogeny & Classification of Coleoptera; vol. 1 (pp. 779-1,006). Warszawa: Muzeum i Institut Zoologii PAN.

LeConte, J. L. (1878). The Coleoptera of Michigan. Proceedings of the American Philosophical Society, 17, 613.  

Leschen, R. A. B. and Beutel, R. G. (2004). Ocellar atavism in Coleoptera: plesiomorphy or apomorphy? Journal of Zoological Systematics and Evolutionary Research, 42, 63-69.

Marshall, A. T. and Thornton, I. W. B. (1963). Micromalthus (Coleoptera: Micromalthidae) in Hong Kong. Pacific Insects, 5, 715-720.

Naomi, S. I. (1987). Comparative morphology of the Staphylinidae and allied groups (Coleoptera, Staphylinoidea). Japanese Journal of Entomology, 55, 450-458.

Pace, R. (1975). An exceptional endogeous beetle: Crowsoniella relicta n. gen. n. sp. of Archostemata Tetraphaleridae from central Italy. Bolletino del Museo Civico di Storia Naturale, Verona; 2, 445-458.

Ponomarenko, A. G. (1985). Coleoptera. In Rasnitsyn, A. P. (ed.): Jurassic Insects of Siberia and Mongolia (pp. 47-87). Moscow: Nauka. 

Ponomarenko, A. G. (2002). Beetles. Scarabaeida. In Rasnitsyn, A. P. (ed.): Late Mesozoic Insects of Eastern Transbaikalia (pp. 164-176). Moscow: Nauka.  

Ponomarenko, A. G. (2003). Ecological evolution of beetles (Insecta: Coleoptera) [electronic version]. Acta Zoologica Cracovensia, 46, 319-328. Retrieved 7/15/14 from http://www.zin.ru/animalia/coleoptera/pdf/ponomarenko_2003.pdf

Pollock, D. A. and Normark, B. B. (2002). The life cycle of Micromalthus debilis LeConte (1878) (Coleoptera: Archostemata: Micromalthidae): historical review and evolutionary perspective [electronic version]. Journal of Zoological Systematics and Evolutionary Research, 40, 105-112. Retrieved 8/31/14 from http://onlinelibrary.wiley.com/doi/10.1046/j.1439-0469.2002.00183.x/pdf 

Rohdendorf, B. B.; Becker-Migdisova, E. E.; Martynova, O. M.; and Sharov, A. G. (1961). Paleozoic insects of Kuznetsky Basin. Trudy Palaeontologicheskogo Instituta AN SSSR, 85, 412-463.

Scott, A. C. (1938). Paedogenesis in the Coleoptera. Zeitschrift Morphologie Ökologie Tiere, 33, 633-653.

Smith, S. G. (1971). Parthenogenesis and polyploidy in beetles. American Zoology, 11, 341-349.

Tan, J.; Wang, Y.; Ren, D.; and Yang, X. (2012). New fossil species of ommatids (Coleoptera: Archostemata) from the middle Mesozoic of China illuminating the phylogeny of Ommatidae. BMC Evolutionary Biology, 12(113), 1-19. Retrieved 7/15/14 from http://www.biomedcentral.com/content/pdf/1471-2148-12-113.pdf

Tan, J.; Ren, D.; Shih, C.; and Yang, X. (2013). New schizophorid fossils from China and possible evolutionary scenarios for archostematan beetles. Journal of Systematic Paleontology, 11(1), 47-62. Retrieved 7/15/14 from http://www.tandfonline.com/doi/abs/10.1080/14772019.2011.637515#.U8RUv0CUW2k      

White, M. J. D. (1973). Animal Cytology and Evolution (3rd. ed.). Cambridge: Cambridge University Press.

Yan, E. V.; Wang, B.; Ponomarenko, A. G.; and Zhang, H. (2014). The most mysterious beetles: Jurassic Jurodidae (Insecta: Coleoptera) from China. Gondwana Research, 25, 214-225. Retrieved 12/20/14 from http://www.researchgate.net/publication/259157836_The_most_mysterious_beetles_Jurassic_Jurodidae_%28Insecta_Coleoptera%29_from_China

Hallelujah: Snaiad is Back!

Giant herbivorous gekkotans on a riverbank ambushed by mega-amphisbaenian: a scene from the Squamozoic

For some enthusiasts of  the evolution and taxonomy of life (such as myself), there is an allure to creating one's own fictitious lineages of life. It is a useless exercise, perhaps, but one that emerges from a deep wonder at the biological profusion in which we live. This experimentation is dubbed speculative evolution, and it can take three primary forms: first, the creation of a biota of a fictitious insular ecological realm that exists on Earth in the here and now—be it an archipelago (Gerolf Steiner's Form and Life of the Rhinogrades), island (Warren Fahy's Fragment) or isolated cave system (Pandemonium, Fahy's less estimable sequel to Fragment); speculation on the appearance of the entire Terran biosphere in the future (Dougal Dixon's After Man) or in a scenario where the evolutionary dice of Earth had rolled differently (the Speculative Dinosaur Project and Darren Naish's "Squamozoic" concept: see his illustration above); and, thirdly, attempts at plausibly conceived alien biospheres: the best of these last include Wayne Barlowe's Expedition and the website "Snaiad: Life on Another World", founded by C. M. Kosemen.

With Snaiad, Kosemen (under the nom de plume Nemo Ramjet) has crowdsourced the task of formulating the biodiversity of an alien world; but it is the attention to taxonomy and physiology imbued by the original author (a paleoartist of great vision) that makes the website's content unique. Rather than creating organisms and then hypothesizing their phyletic relations, he sketches cladograms first (see left) and then populates them with fictitious taxa: this results in a convincingly thought-out fiction. 

A few turtiform species (illustrated by Kosemen)

To provide many specifics on Snaiadi life would steal Kosemen's fire, so to speak, so let's just say that the best overall aspect of the project is its tendency to strike a balance between scientific realism and unconventionality: that is, the life forms are suitably dissimilar to what we are familiar with, yet are developed in a consistent and sensible manner. One (small) downside to the website is that the only taxa that have been covered in detail on the website are those that together comprise the rough Snaiadi analog to tetrapods; but considering the meticulous care with which these organisms are shaped, it is an understandable (and excusable) defect.    


The site had been taken offline in 2010 for revision, and I had almost given up hope of ever glimpsing the denizens of Snaiad again. But no longer: I have just made the discovery that the site is once again available (since July of this year).

Was it worth the four-year wait? Yes.

Innard-Drinking Caterpillars and Others

Lithograph by Ernst Haeckel displaying moths of the families Plutellidae, Alucitidae, and Pterophoridae

Of the "Big Four" orders of the Insecta (Coleoptera, Lepidoptera, Hymenoptera, and Diptera), the Lepidoptera (moths, and the diurnal moths known as "butterflies") are reputed as the most-studied and best-understood (Gaston, 1991). I have observed that this reputation (which results from the enduring appeal borne by those ever-popular insects, the Papilionoidea) is often held without question amongst the entomologically inclined—unfortunate, given its falsehood: the excellent systematic knowledge of the butterfly/macro-moth* faunas of a few scattered regions in the Northern Hemisphere is by no means a synecdoche for the state of that field with regard to the remainder of the order's constituents (Kristensen et al., 2007). The micro-moths (as the non-Macrolepidoptera* are termed), which constitute the majority of the Lepidoptera, remain undoubtedly neglected in the realm of description and taxonomy.

Tinagma gaedikei (Douglasiidae), known only in association with Miami mist (Phacelia purshii) (©microleps)

This neglect can be imputed to many factors, only one of which I choose to address here: the structural and ecological uniformity of the clade Ditrysia, which, as its members constitute the vast majority of lepidopteran species, unavoidably reflects on the order as a whole—uniformity relative to the  trio of coevally speciose orders mentioned earlier, that is. Seeming consistency in gross ditrysian ethology belies an overall profusion of ecological detail amongst them—such as the specialization to host plant often seen herein (of which the moth shown above is a prime example; Harrison, 2005). But this consistency retains an essence of truth in that imaginal† ditrysians are overwhelmingly non-feeding or nectarivorous, and soft herbivorous tubes as larvae: to quantify, the latter characteristic is applicable to 99% of lepidopterans (Pierce, 1995). This essential reality has deterred research into Lepidoptera: to a degree, the order is seen as a dull option for study in the eyes of some entomologists.

Eupithecia orichloris (Geometridae) grappling with what appears to be a staphylinid beetle

But there are many exceptions to this rule of homogeneous lepidopteran ecology: rather than feed on pollen or seeds as do most members of their genus, the inchworms within Eupithecia endemic to Hawaii are equipped with tarsal motion-attenuated sensillae and elongated claws, both used to pounce upon small prey (Montgomery, 1983); predation on auchenorrhynchans has also been observed in the caterpillars of one metalmark butterfly (Riodinidae; DeVries et al., 1992), nor can I possibly ignore the famed diversity of ant-larva-chowing myrmecophilous caterpillars among the riodinids and the closely related Lycaenidae (blues, hairstreaks, etc.) (Fiedler, 2012). Nor are predaceous larvae limited to the Macrolepidoptera: the caterpillars of certain Pyralidae are known to attack scale insects (Mann, 1969; Neunzig, 1997); and as a bagworm (Psychidae), the Panamanian Perisceptis carnivora possesses a protective case: but being a non-herbivore, it crafts its case from the remains of its prey (Davis et al., 2008).

Euclemensia bassettella photographed by Mark Dreiling

However, I primarily wrote this post with the intent of addressing the protelean parasitoids‡ among the Lepidoptera. Considering the diversity of the order (~174,000 spp.), it is no wonder that this mode of existence has evolved on multiple twigs of the lepidopteran phylogram: but it is equally remarkable—given this same diversity—that less than 0.15% of these species are parasitoids (Pierce, 1995). Although I can find no comprehensive enumeration of the number of butterflies and/or moths which exhibit the parasitoid syndrome, it does appear that such adaptations tend to originate at species level: the parasitoid of paper wasp larvae (Polistes spp.) Chalcoela pegasalis (Hodges et al., 2003) is classified within a family largely consisting of humdrum phytophages (Crambidae), as are the gelechioids Euclemensia bassettella (Cosmopterigidae) and Zenodochium coccivorella (Blastobasidae) (although blastobasid caterpillars tend more towards detritovory; Watson & Dallwitz, 2011); the hosts of both these latter moths are scale insects (Coccoidea) (Rau, 1941).

This taxonomic artifact is at odds with what is observed in another mega-diverse insect order with a scarcity of parasitoids: the Coleoptera (beetles). Only one parasitoidal lineage of these famously speciose elytron-bearers is ranked at or below generic level: namely, the genus Aleochara (Staphylinidae: Aleocharinae), which with the exception of one species, are larval ectoparasitoids of cyclorrhaphous fly pupae (Peschke & Fuldner, 1977; Peschke et al., 1996). Contrastingly, there are only two exclusively parasitoidal lepidopteran families: the related Epipyropidae and Cyclotornidae (both classified within the superfamily Zygaenoidea).

Final-instar caterpillar of Fulgoraecia exigua on acanaloniid; photographed by Gary McClellan

Epipyropids are the more speciose of the pair, and most diverse in the Oriental and Australasian ecozones (only one species is known from my native Nearctic; Covell, 2005); their hosts are planthoppers (Fulgoroidea). One species (Agamopsyche threnodes) is parthenogenetic (Perkins, 1905). Similarly to such unrelated insects as strepsipterans (not to mention mantispids and acrocerids), "planthopper parasite moths" are hypermetamorphic, with all of the attributes that this lifestyle entails: a dispersal stratagem necessitating copious broods (3,000 eggs per brood in Fulgoraecia sp.), the hatching of which may be staggered to increase chances of larvae locating hosts (Kirkpatrick, 1947); in their inaugural instar, these dispersive larvae have disproportionately large heads and thoraxes, along with tapering abdomens—upon reaching a planthopper and adhering to its abdomen with its claws, an epipyropid larva moults into a dorsally convex and heavily corrugated caterpillar which exudes an increasingly thick layer of white polyethylene-like paraffin (Marshall et al., 1977), sucking its host's innards with serrated needle-mandibles on a head that can be retracted into its owner's obese body.

Cyclotornids (consisting of five Australian species within the genus Cyclotorna; Common, 1990) exhibit strong ontogenetic parallels with the Epipyropidae. Female moths spread their eggs adjacent to ant trails (in Cyclotorna monocentra, those created by the dolichoderine Iridomyrmex purpureus); the miniscule first-instar larvae (of similar proportions to their epipyropid cousins) literally gallop along these thoroughfares (Common, 1990), which lead to aggregations of leafhoppers (Cicadellidae) farmed by I. purpureus. These cicadellids serve as initial hosts, the cyclotornid larvae oriented upon them similarly to epipyropids upon planthoppers (situated upon the abdomen below the wings): later instars (flattened and broad by comparison to the first) detach from their leafhopper hosts: exuding allomones attractive to the leafhopper-attending ants, the larvae are then borne back to the I. purpureus colony, where they reside as myrmecophiles; appeasing their hosts chemically whilst preying on the latter's brood before pupation in what is one of the more complicated ecological transitions any insect undergoes through metamorphosis (Dodd, 1912).

To conclude, not all the Lepidoptera are so uninteresting (or so deeply understood) as their repute would lead us to believe.    

*The Macrolepidoptera is a probably monophyletic (Minet, 1991) clade including not only the butterflies (Papilionoidea) and the related skippers (Hesperioidea), but also such familiar moth families as the Geometridae (inchworms), Sphingidae (sphinx moths), the diverse Noctuidae (owlet moths and others), among many.
†Adult.
‡That is, parasitoids only when immature. 
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Common, I. F. B. (1990). Moths of Australia. Melbourne: Melbourne University Press. 

Covell, C. V. (Jr.) (2005).  A Field Guide to Moths of Eastern North America. Martinsville: Virginia Museum of Natural History.

Davis, D. R.; Quintero A., D.; Cambra T., R. A.; and Aiello, A. (2008). Biology of a new Panamanian bagworm moth (Lepidoptera: Psychidae), and eggs individually wrapped in setal cases [electronic version]. Annals of the Entomological Society of America, 101(4), 689-702. Retrieved 5/18/14 from http://esa.publisher.ingentaconnect.com/content/esa/aesa/2008/00000101/00000004/art00002      

DeVries, P. J.; Chacon, I. A.; and Murray, D. (1992). Toward a better understanding of host use and biodiversity in riodinid butterflies (Lepidoptera). Journal of Research on the Lepidoptera, 31(1-2), 103-126.

Dodd, F. P. (1912). Some remarkable ant-friend Lepidoptera. Transactions of the Entomological Society of London, 1911, 577-590.

Fiedler, K. (2012). The host genera of ant-parasitic butterflies: a review. Psyche, 153975, 1-10. Retrieved 5/16/14 from http://www.hindawi.com/journals/psyche/2012/153975/ 

Gaston, K. J. (1991). The magnitude of global species richness. Conservation Biology, 5, 283-296.

Harrison, T. L. (2005). A new species of Douglasiidae (Lepidoptera) from the eastern Nearctic [electronic version]. Proceedings of the Entomological Society of Washington, 107(3), 596-603. Retrieved 5/16/14 from http://www.biodiversitylibrary.org/page/32143328#page/608/mode/1up  

Hodges, A.; Hodges, G.; and Espelie, K. E. (2003). Parasitoids and parasites of Polistes metricus Say (Hymenoptera: Vespidae) in northeast Georgia. BioOne, 96(1), n.p.

Kirkpatrick, T. W. (1947). Notes on a species of Epipyropidae (Lepidoptera) parasitic on Metaphaena species (Hemiptera: Fulgoridae) at Amani, Tanganyika [electronic version]. Proceedings of the Royal Entomological Society of London, Series A: General Entomology; 22(4-6), 61-64. Retrieved 5/25/14 from http://onlinelibrary.wiley.com/doi/10.1111/j.1365-3032.1947.tb01108.x/abstract  

Kristensen, N. P.; Scoble, M. J.; and Karsholt, O. (2007). Lepidoptera phylogeny and systematics: the state of inventorying moth and butterfly diversity [electronic version]. Zootaxa, 1668, 699-747. Retrieved 5/16/14 from http://www.lepidoptera.ee/images/lingid/Zootaxa1668p699.pdf    

Mann, J. (1969). Cactus-feeding insects and mites. USNM Bulletin, 256, 30-158. Retrieved 5/17/14 from http://archive.org/stream/bulletinunitedst2561969unit#page/158/mode/2up

Marshall, A. T.; Lewis, C. T.; and Parry, G. (1974). Paraffin tubules secreted by the cuticle of an insect Epipyrops anomala (Epipyropidae: Lepidoptera) [electronic version]. Journal of Ultrastructure Research, 47(1), 41-60. Retrieved 5/23/14 from http://www.sciencedirect.com/science/article/pii/S0022532074900252

Montgomery, S. L. (1983). Carnivorous caterpillars: the behavior, biogeography and conservation of Eupithecia (Lepidoptera: Geometridae) in the Hawaiian Islands [electronic version]. GeoJournal, 7(6), 549-556. Retrieved 5/16/14 from http://link.springer.com/article/10.1007%2FBF00218529 

Minet, J. (1991). Tentative reconstruction of the ditrysian phylogeny (Lepidoptera: Glossata). Entomologica Scandinavica, 22, 69-95.   

Neunzig, H. H. (1996). The Moths of North America North of Mexico, fasc. 15.4.: Phycitinae (part). Bakersfield: the Wedge Entomological Research Foundation.

Perkins, R. C. L. (1905). Leaf-hoppers and their natural enemies (Pt. II: Epipyropidae) Lepidoptera. Bulletin of the Hawaiian Sugar Planter's Association Experimental Station Entomological Series, 84(1), 75-85. 

Peschke, K. and Fuldner, D. (1977). Uebersicht und neue Untersuchungen zur Lebensweise der parasitoiden Aleocharinae (Coleoptera; Staphylinidae). Zoologische Jahrbuecher (Systematik), 104, 242-262.

Peschke, K.; Mittmann, B.; and Fuldner, D. (1996). Aleochara clavicornis, a stepping stone in the evolution of parasitoid behavior within the rove beetle genus Aleochara (Coleoptera, Staphylinidae). Proceedings of the XXth International Congress of Entomology, Firenze, August 25-31.

Pierce, N. E. (1995). Predatory and parasitic Lepidoptera: carnivores living on plants. Journal of the Lepidopterists' Society, 49, 412-453. 

Rau, P. (1941). Observations on certain lepidopterous and hymenopterous parasites of Polistes wasps [electronic version]. Annals of the Entomological Society of America, 34(2), 355-366. Retrieved 5/21/14 from http://www.researchgate.net/publication/233678369_OBSERVATIONS_ON_CERTAIN_LEPIDOPTEROUS_AND_HYMENOPTEROUS_PARASITES_OF_POLISTES_WASPS 

Watson, L. and Dallwitz, M. J. (2011). Blastobasidae. Retrieved 5/21/14 from http://delta-intkey.com/britin/lep/www/blastoba.htm 

Glimpsing Armadillo Ants

One of the favorite books of my formative years (and also the favorite, I am sure, of a few others) was Bert Hölldobler and Edward O. Wilson's tome The Ants: a synthesis of the sum total of myrmecological knowledge up to 1990, and winner of the 1991 Pulitzer Prize in non-fiction (perhaps the only straight-up textbook to have ever done so; Yee, 2004). As an incipient preadolescent entomologist, my favorite part of the book's contents was the section devoted to collated line drawings and profiles of all ant genera considered valid at the time (organized by subfamily).

Peruvian worker of T. tatusia; photograph by Erin Prado

By poring over these figures time and time again, I was gradually familiarized with the distinctive silhouettes of many an ant, solidifying the more morphologically peculiar ones in my memory (the adorably wacky Discothyrea comes to mind here). Among these more striking sketches was one detailing the morphology of a species by the name of Tatuidris tatusia, contained in the Myrmicinae: in my usual learning process, I looked the name up in the index to find if any data were contained elsewhere in the book on the taxon. But The Ants would yield no information on T. tatusia, other than that it was the sole extant member of the myrmicine (Carpenter, 1930) tribe Agroecomyrmecini. It made perfect sense to me that Tatuidris (the etymology of the name suggested the ant's epithet "armadillo"; Lacau et al., 2012) should have a tribe all to itself—what with its generally weird habitus (a combination of a prominent stinger, clubbed antennae, and distinctively heart-shaped face); but this strangeness further made me wonder whether it was genuinely myrmicine in identity (doubts that were incidentally shared by some taxonomists, as we shall see).

Aside from Tatuidris, the armadillo ants include only the extinct genera Agroecomyrmex (from Baltic amber; Wheeler, 1914) and Eulithomyrmex (from the Coloradoan Florissant Formation; Carpenter, 1935): both date to the Paleogene Period (the latter about 10 million years younger than the former; Ritzkowski, 1997; Foos & Hannibal, 1999). Their assignment to the Myrmicinae (one of the most speciose single subfamilies within the Formicidae) was made on the basis of morphological similarities to members of the tribe Phalacromyrmecini, and, to a lesser extent, Dacetini (Brown & Kempf, 1968; Brown, 1977; Bolton, 1984): these common characteristics include an expanded facial vertex and deepened scrobes* (the extension of which all the way back to the eyes is another distinctive quality of Tatuidris; Baroni Urbani & de Andrade, 2007). Right from the description of the first living agroecomyrmecine (T. tatusia) these traits were suspected of being only dubiously indicative of kinship (Brown & Kempf, 1968; Bolton, 1984): speciousness affirmed by the elevation of the Agroecomyrmecini to subfamily rank (Bolton, 2003), although the first fully cladistic analysis of T. tatusia affirmed its relation to the Dacetini and inclusion within the Myrmicinae (Baroni Urbani & de Andrade, 2007). 

Ecuadorian bullet ant (Paraponera clavata) photographed by Alex Wild (who else?)

Classifying armadillo ants within their own subfamily—as is the prevalent opinion at the moment—still begs an answer to their true phylogeny. Two opposing theories seem to have arisen on the matter of agroecomyrmecine placement within the Formicidae: one regards the subfamily as sister-group of the Myrmicinae (Bolton, 2003); the other, as within the grab-bag of "poneromorph" subfamilies (the Amblyoponinae, Ectatomminae, Heteroponerinae, Paraponerinae, Proceratiinae, and Ponerinae) which sit at the base of the "formicoid" clade in which the Myrmicinae is placed (Ward, 2009): specifically, close to the monotypic Paraponerinae (Brady et al., 2006) or near the Amblyoponinae (Rabeling et al., 2008). The results of one mainly morphological study resolve the ambiguity by deriving the Myrmicinae as both within the "poneroids" (Keller, 2011) and akin to the armadillo ants. 

Variation in pilosity patterns within T. tatusia (Donoso, 2012)

With all of this ambiguity, one can only wonder if biological data on the only extant armadillo ant would be at all informative in agroecomyrmecine phylogeny. T. tatusia has been collected throughout southern Mesoamerica and northern South America, reaching greatest abundance in upland areas (largely between 800 and 1,200 meters in altitude); the species includes multiple morphs throughout its range (which on one occasion caused the mistaken description of new species; Lacau et al., 2012) and exhibits  an unusual degree of intraspecific genetic variation: this suggests either that the population in fact consists of several cryptic species that taxonomists do not yet have the information to confidently delineate, or that it is a lineage in the process of allopatric speciation (Donoso, 2012).

Almost nothing is known of the habits of T. tatusia, given that until recently none had been observed in life: but its weirdly elongated stinger and thickly interlocking setae on the inner margins of the mandibles—not to mention intramandibular glands clustered in a manner unknown in other ants (Billen & Delsinne, 2013)—have encouraged speculation on the ant's presumably unorthodox biology. In further tantalization, the discovery of the first live colony (containing erstwhile-unknown drones and queens) revealed only that armadillo ants have a diet that does not include the following likely items:

" ... live and dead termites, millipedes, mites, various insect parts, sugar water, tuna, biscuits, live and dead fruit flies (Drosophila), live springtails, live myriapods (Chilopoda and Diplopoda) [centipedes and millipedes], live and dead Diplura, small live spiders, small live pseudoscorpions, one small snail, uncooked hen egg ... ant larvae (Gnamptogenys sp.), and live ant workers (Cyphomyrmex sp., Brachymyrmex sp.)." (Donoso, 2012)

Hence, we can only assume that T. tatudris is a most specialized predator. Of what, precisely, remains to be seen whenever science captures its next glimpse of armadillo ants. 

                           

*Cephalic slots into which antennae can be retracted.
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Baroni Urbani, C. and de Andrade, M. L. (2007). The ant tribe Dacetini: limits and constituent genera, with descriptions of new species. Annali del Museo Civico di Storia Naturale "G. Doria", 99, 1-191.

Billen, J. and Delsinne, T. (2013). A novel intramandibular gland in the ant Tatuidris tatusia (Hymenoptera: Formicidae). Myrmecological News, 19, 61-64. Retrieved 5/8/14 from http://bio.kuleuven.be/ento/pdfs/billen_delsinne_myrmnews_2013.pdf

Bolton, B. (1984). Diagnosis and relationships of the myrmicine ant Ishakidris gen. n. (Hymenoptera: Formicidae). Systematic Entomology, 9, 373-382.

Bolton, B. (2003). Synopsis and classification of Formicidae. Memoirs of the American Entomological Institute, 71, 1-370.

Brady, S. G.; Schultz, T. R.; Fisher, B. L.; and Ward, P. S. (2006). Evaluating alternative hypotheses for the early evolution and diversification of ants. Proceedings of the National Academy of Sciences of the United States of America, 103(48), 18172–18177.

Brown, W. L. (1977). An aberrant new genus of myrmicine ant from Madagascar. Psyche, 84, 218-224.

Brown, W. L. and Kempf, W. W. (1968). Tatuidris, a remarkable new genus of Formicidae (Hymenoptera). Psyche, 74, 183-190.


Carpenter, F. M. (1930). The fossil ants of North America [electronic version]. Bulletin of the Museum of Comparative Zoology, 70(1), 1-66. Retrieved 5/7/14 from http://gap.entclub.org/taxonomists/Carpenter/1930.pdf

Carpenter, F. M. (1935). A new name for Lithomyrmex Carp. (Hymenoptera) [electronic version]. Psyche, 42(2), 91. Retrieved 5/6/14 from http://www.hindawi.com/journals/psyche/1935/068604/abs/   

Donoso, D. A. (2012). Additions to the taxonomy of the armadillo ants (Hymenoptera, Formcidae, Tatuidris) [electronic version]. Zootaxa, 3503, 61-81. Retrieved 5/8/14 from http://mapress.com/zootaxa/2012/f/zt03503p081.pdf 

Foos, A. and Hannibal, J. (1999). Geology of Florissant Fossil Beds National Monument. Retrieved 5/5/14 from http://www2.nature.nps.gov/geology/education/foos/flfo.pdf    

Hölldobler, B. and Wilson, E. O. (1990). The Ants. The Belknap University Press of Harvard University Press: Cambridge.

Lacau, S.; Groc, S.; Dejean, A.; de Oliveira, M. L.; and Delabie, J. H. C. (2012). Tatuidris kapasi sp. nov.: a new armadillo ant from French Guiana (Formicidae: Agroecomyrmecinae). Psyche, 2012(2012), 926089, 1-7. Retrieved 5/8/13 from http://www.hindawi.com/journals/psyche/2012/926089/ 

Rabeling, C.; Brown, J. M.; and Verhaagh, M. (2008). Newly discovered sister lineage sheds light on early ant evolution. Proceedings of the National Academy of Sciences, USA; 105, 14913-14917.

Ritzkowski, S. (1997). K-Ar-Altersbestimmungen der bernsteinführenden Sedimente des Samlandes (Paläogen, Bezirk Kaliningrad). Metalla, Bochum; 66, 19-23.

Ward, P. S. (2009). Phylogeny, classification, and species-level taxonomy of ants (Hymenoptera: Formicidae) [electronic version]. Zootaxa, 1669, 549-563. Retrieved 5/8/14 from http://wardlab.files.wordpress.com/2012/01/ward_2007c_zoootaxa.pdf 

Wheeler, W. M. (1914). The ants of the Baltic amber. Schriften der Physikalisch-Okonomischen Gesellschaft, 55(4), 56-59.

Yee, D. (2004). The Ants: Bert Hölldobler + Edward O. Wilson. Retrieved 5/7/14 from http://dannyreviews.com/h/Ants.html