• ;, (.':>i ~'1,(v:\).~ ~,v.A. tqC{z 12~.~. ~ ~I 1 A/~z. - 40~li"";..~..~:., r ,'t TWENTY -EIGHT {. ~W r~),.'.'~ ~.aTTp..c. L !<'{{e .~. The neuropteroid orders of Central America (Neuroptera and Megaloptera) CHARLES S. HENRY, NORMAN D. PENNY, AND PHILLIP A. ADAMS INTRODUCTION strap-like, coriaceous front wings, not unlike the elytra of beetles. The order is among the most biologically and mor­ Imagine that you are a student in a course on insect identi­ phologically diverse in all Insecta. fication, and you are presented by your instructor with an /~ the Neuroptera is no success story, compared with other 'unknown' to classify, merely to order. It has extremely long, knobbed antennae, like a butterfly; perhaps it is a lepidopteran. Yet its wings are membranous, narrow, and strong, and it has ( \ !}l':'I /. legs that are spiny and obviously modified for seizing small I insect prey items during flight; these are characteristics of a , dragonfly, order Odonata. But yellowish-white markings on the rather fat abdomen, together with a narrow waist, give the .II/~·~~ specimen a wasp-like appearance: it could be in the Hymen­ , optera, or maybe a good wasp-mimicking fly (order Diptera). Examine the compound eyes: each is extremely large, as one expects of an odonate, but also divided by a deep sulcus into an upper and lower half, as in certain male mayflies-is the insect an aberrant ephemeropteran? Finally, you decide that your instructor has glued together the parts of many insects, to fool you. In fact, however, you have just been introduced to the peculiar, fascinating order of insects known as Neuroptera, and you are looking at a member of one of its most curious families, the Ascalaphidae or owlflies (Fig. 28.1). One learns to expect the unexpected in the Neuroptera. bisected "" Within the order, there are insects that trap their prey with eye funnel traps built in the sand (Myrmeleontidae), chase small insects across the desert floor on stilt-like legs (Nemopteridae), browse under the water on freshwater sponges (Sisyridae), live among ants and feast on the colony's brood (Chrysopidae: Italochrysa), and even kill their termite prey by blasting them with a lethal gas from the rear end (Berothidae). Some neur­ opterans (Ascalaphidae) in Europe have wide, brightly coloured wings, and for this reason were once placed in the butterfly genus Papilio; others possess extremely long, thread-like hind wings that trail out behind them in flight (Nemopteridae). The members of one widespread family faithfully duplicate nearly every major feature of the praying mantises, including their powerful raptorial front legs and elongated prothoraces (Fig. 28.5), yet as youngsters, these 'mantispids' (Mantispidae) para­ c.s.~ sitize spiders and social insects and look like maggots. And Fig. 28.1 Ululodes mexicana, nonnal resting position (Ascalaphidae) at least one aberrant dusky-wing (Coniopterygidae) possesses [Arizona, original]. THE NEUROPTEROID ORDERS 433 insect orders. At a mere SOOO-odd species, the order is min­ RsMA MP1+2 uscule compared with the Hemiptera (100 000 species), Diptera (85 000), Hymenoptera (c. 200 000), Lepidoptera (120 000), or Coleoptera (400000). Nor is it particularly well-defined: whereas each of the large orders above is homogeneous and united by clear synapomorphies (unique, specialized features shared among its members), neuropteran families are united principally by primitive (plesiomorphic) features, often shared with other ancient orders. 'Neuroptera' is also used differently by different authors. To some, it includes the Megaloptera base (dobsonflies and alderflies) and Raphidioptera (snakeflies), while to others, it is restricted to the so-called planipennian families, characterized by larvae that possess piercing, sucking mouthparts of a particular sort. Here, we choose to restrict Neuroptera, but we acknowledge the possible monophyly of Neuroptera, Megaloptera, and Raphidioptera by including all three orders in our discussion; to avoid confusion, we will refer to the three orders together as 'neuropteroids'. Oddly, the closest living relatives of the neuropteroids are probably Coleoptera, the most speciose of insect taxa. Most of the smaller, Fig. 28.2 Platyneuramus sarar (Hagen) (Corydalidae) (redrawn from older orders of holometabolous insects are also related evol­ Glorioso and Flint 1984). CuA, cubitus anterior; CuP, cubitus posterior; utionarily to species-rich groups: the Trichoptera to the Lepi­ MA, media anterior; MP1 + 2, fused anterior and posterior branches of doptera, the Mecoptera to the Diptera, and the Symphyta to the media posterior; Rs, radial sector; lA, first anal vein. aculeate Hymenoptera. In each of these cases, as in that of the neuropteroids, it seems that some evolutionary breakthrough, sopidae and Ascalaphidae, which have experienced more recent originating within a derivative taxon of the parental, primitive evolutionary success, attain highest diversity in the humid order, precipitated rapid speciation and adaptive radiation of tropics. those inheriting the valued feature. Eventually, the vigorous Central America and Panama possess a diverse neuropteroid child, favoured by its new technology, far outgrew its parent. fauna, perhaps because the region serves as a crossroads Relatively species-poor orders like the three comprising the between the distinctive adaptive radiations of North and South neuropteroid complex, then, are relict collections of diverse, America. Consequently, the larger, more cosmopolitan taxa are generally primitive taxa that happen to have escaped extinc­ disproportionately represented here: each of the major families tion; and because extinctions have removed many of the inter­ Mantispidae, Hemerobiidae, Chrysopidae, Ascalaphidae, Myr­ mediate, transitional forms that once existed in the complex, meleontidae, and Coniopterygidae is a major component of the neuropteroids present major problems to entomologists inter­ Central American entomofauna, and consists largely of genera ested in classification and phylogeny. with their centres of diversity in South America. Unfortunately, As relict, ancient groups, the neuropteroid orders and their some of the most ancient and bizarre families, mentioned in the families show very interesting, often disjunct geographical dis­ preceding paragraph, are absent from the New World tropics. tributions, which reflect the past excursions of the continents. Nevertheless, the neuropteroids ofthis region hold great interest A good number of families reach maximal diversity in bio­ for amateur and professional entomologists alike. geographically isolated regions like Australia or South Africa, and several taxa have typical Gondwanaland (southern hemi­ sphere) distributions. For example, Nymphidae is confined to GENERAL BIOLOGY AND the Australian region, while Psychopsidae (silky lacewings) shows high generic endemism in South Africa, Central Asia, EVOLUTION and Australia. In addition, several other families, including the two neuropteran sister-taxa Berothidae and Mantispidae, show Neuropteroids are endopterygote or holometabolous insects, striking phylogenetic ties between the South American and meaning that the life cycle is characterized by internally devel­ South African representatives (Aspock and Asp6ck 1988; oping wing pads and complete metamorphosis. Complete meta­ Tjeder 1959). Other families with peculiar, relict distributions morphosis, in which the adult insect differs radically in include Rapismatidae, which is scattered through parts of appearance and habits from its earlier immature, larval stages, central Asia, and Polystoechotidae (giant lacewings), restricted confers great evolutionary advantages, principally through to the New World from parts of North America to Chile. In the exploitation of different ecological niches by different Iife­ general, the oldest neuropteroid groups are more diverse in stages of the same organism. However, the process of metamor­ temperate, desert, or montane areas, while taxa like Chry- phosis is very difficult and risky, and the more generalized 434 28. HENR Y, PENNY, AND ADAMS throughout larval life, because the hindgut and rectum are closed off from the midgut, and are eliminated as a 'meconial pellet' by the new adult while the wings and body sclerites are hardening. The larvae of the vast majority ofneuropteroids, and all of those in the New World tropics, are voracious predators of other invertebrates. The Ithonidae, whose larvae ingest flUids from decaying plant litter, is the only family for which a non­ predatory immature has been documented (New 1986a)~ Although the larvae of most neuropteroids are terrestrial, those of a few families are semi- or totally aquatic. All Mega­ loptera, for example, are underwater predators during their larval stages, breathing through specialized abdominal gills. Fig.l8.3 Glenurus luniger Gerst. (Myrmeleontidae) [Arizona, original] CuA, Sisyridae, too, have subaquatic larvae, which feed on fresh­ cubitus anterior; CuP, cubitus posterior; CuP + I A, fused CuP and first anal water sponges. A few Osmylidae and Neurorthidae are also veins; MP, media posterior. closely associated with fresh water, but these two families are not found in Central America. At the other extreme are neur­ opteroids like Myrmeleontidae, Ascalaphidae, and Nemop­ neuropteroids like Megaloptera and Raphidioptera seem not to teridae, whose larvae can survive in extremely arid areas. have perfected it; pupation and transformation consume much Most neuropteroids pass through