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SYSTEMATICS OF TERRESTRIAL ARTHROPODS 4: HEXAPODA

(INSECTS IN BROAD SENSE)

Niels Peder Kristensen

Entomology Department Natural History Museum of Denmark: Zoological Museum

E N T O M O L O G Y Course Spring 2004

1 About the textbook, and about hexapod literature in general

The textbook. As far as hexapods are concerned the examination requirement of this course is I. D. Naumann (ed.) Systematic and Applied Entomology. An Introduction, Melbourne University Press 1994, EXCEPT chapters 4 and 6-10 (which, however, make stimulating and informative reading; concerning chapter 6, see below) BUT INCLUDING the present set of lecture notes, which comprise additions and comments to the account given in the textbook, which here will be referred to as “SAE”. As evident from the preface of SAE, it is based on a large (two-volume) work: CSRIO (ed), The Insects of Australia 1-2, 1137 pp. Melbourne University Press 1991 (see below). Several of the introductory chapters are identical in the two books, but The Insects of Australia moreover includes some extra, more special, chapters (on the history of Australian entomology, on “Insects and Humans in Australia”, and on “Australian Insects in Scientific Research”); on the other hand chapters 8 and 9 in SAE are newly written for this particular book. The chapters on the individual orders are far more extensive in The Insects of Australia, where they include accounts of all families/subfamilies present in Australia. SAE has, for every order, a concluding section on “Special features of the Australian Fauna”, and similarly the systematics overviews present estimates on Australian species numbers for the individual families; these details, of course, are of no particular relevance in the context of the present course. In the notes here some succinct notes on Danish /N.European species numbers are given, and in a number of cases the classification within the individual orders, with emphasis on particularly important subgroups.

Comprehensive works. Two series of major reference works should be known to all workers dealing with in systematic/general entomology, namely Grassé, P.P. (ed). Traité de Zoologie. VIII-X (1949-79) Insectes; vol. VIII in many, vol. X in two "fascicules". The systematic accounts are in IX (1949) & X (1951) hence, of course, now considerably outdated. Beier, M., later Fischer, M., later still Beutel, R. & Kristensen, N.P.K. (eds) Handbuch der Zoologie/Handbook of Zoology. Arthropoda, Insecta, 2nd ed. since 1968. Still in course of publication. A few of the smaller hexapod 'orders' (Diplura, Zygentoma, Mantophasmatodea, Siphonaptera) are not yet treated, and of the major endopterygote 'orders' only volumes dealing with the Diptera, Lepidoptera and Hymenoptera-'Symphyta' have appeared. The first of three planned volumes on Coleoptera is nearing completion. Recent issues are (and all future ones will be) in English. The individual chapters/issues in the Traité as well as in the Handbuch/Handbook series are of very unequal quality. The most recent, somewhat detailed, systematic handbook account of the arthropods as a whole in Parker, S. (ed.) Synopsis and Classification of Living Organisms, vol.2, New York etc., McGrawHill, 1982. Arachnida pp. 72-169, Insecta pp. 326-680, Myriapoda pp. 681-726. A multi- author treatment with special emphasis on family-group taxa. Unfortunately 'under-illustrated'. The entognathan hexapods have been inadvertently omitted in this work! Three books by R. Matsuda on the tagmata of the hexapod body: Morphology and evolution of the insect head. Mem. amer. ent. Inst. 4, 334 pp., 1965, Morphology and evolution of the insect thorax. Mem. ent. Soc. Can., 76, 431 pp., 1970, Morphology and evolution of the insect abdomen. Oxford, Pergamon Press, 543 pp., 1976, are immensely useful references with (for their time) near-exhaustive bibliographies. However, Matsuda's own interpretations, and his original contributions, are partly problematical. The head

2 and thorax books are essentially about adult skeletomuscular anatomy. In contrast, the abdomen book has no musculature account, but considers morphogenesis in some detail; it also treats the internal genitalia. As far as the head and abdomen (i.e., abdominal skeletomuscular structure) are concerned, the accounts by (Denis &) Bitsch's in the Traité de Zoologie are far better. The head is in VIII(I), 1973, the abdomen in VIII(II), 1979 (where one also finds a French version of Matsuda's thorax account; a little condensed, but also a little updated). The morphology (including ultrastructure) of internal organs is largely treated in the physiological literature. A most comprehensive (13-volume) account of insect physiology was published in 1985: G.A. Kerkut & L.J. Gilbert (eds) Comprehensive Insect Physiology, Biochemistry & Pharmacology, Oxford, Pergamon Press. The most modern reference on organs other than the skeletomuscular system is a three-volume treatise edited by Harrison, F. W. & Locke, M. 1998: Microscopical Anatomy of the Invertebrates, 11A-C, Insecta A-C. New York, Wiley. Unfortunately, treatments of some organ types (chemoreceptors, simple eyes, testes, etc.) are entirely lacking.

Condensed accounts. The above-mentioned CSRIO (ed), 1991: The Insects of Australia 1-2, 1137 pp. Melbourne University Press together with Richards, O.W. & Davis, R.G. (eds) 1977: Imms' General Textbook of Entomology 1-2, 1354 pp, Chapman & Hall, have long been considered the leading compact references on hexapod anatomy-physiology-systematics. The latter (evidently somewhat outdated) has a much more detailed general part, while the systematic treatment is more authoritative and up-to-date in the latter (which is multi-authored); of course it is a limitation that non-Australian taxa below 'ordinal' level are omitted. The recently published 'revised Insect Kaestner', i.e., Dathe, H. (ed) Lehrbuch der Speziellen Zoologie. Begründet von A.Kaestner, 2 Auflage, Band I: Wirbellose Tiere, 5. Teil: Insecta. Spektrum 2003, largely replaces vol. 2 (systematics) of 'Imms', though the coverage of the various orders is somewhat uneven, and references are sparser. F. Stehr (ed.). Immature Insects. 1-2 (1987, 1991) is a most useful treatment of (external) morphology and identification of insect nymphs and -larvae. Based on the North American fauna, but widely applicable. There are some single-volume entomology textbooks which treat physiology, adaptations, behaviour etc in more detail than does the SAE. Examples are Gillot, C. Entomology, New York, Plenum (2nd ed. 1995) and Gullan, P. & Cranston, P. Insects. An Outline of Entomology, Blackwell, (rev ed., 2000). Chapman, R. F. The Insects. Structure and Function, Cambridge, Cambridge University Press (4th ed. 1998) is probably the best compact account of insect physiology; morphology is treated in less detail.

Reviews. Review articles in Annual Review of Entomology are important introductions to the literature on many topics. The same is true of many articles in the more recently initiated Annual Review of Ecology & Systematics series.

Literature on Danish/N.European hexapods. M. Chinery’s Collins Guide to the Insects of Britain and Western Europe is available in a Danish edition (translated/revised by Henrik Enghoff) Vesteuropas Insekter (Gad 1987, there are later reprints). It treats (with mostly excellent illustrations) a sizable selection of European insects and, more succinctly, other terrestrial arthropods. Undoubtedly the most useful introduction to the diversity of our hexapod fauna – it is highly recommended to anybody interested in acquiring familiarity with this fauna. Another, similarly recommendable book in the same category is Douwes, P., Hall, R., Hansson, C. & Sandhall, Å: Insekter. En fälthandbok, Interpublishing, Stockholm 1997. It is less richly (but still

3 richly – with good colour photographs) illustrated than the Chinery book, but is more technical, with identification keys to superfamily/family level. The principal series of identification manuals of relevance are Danmarks Fauna (publication of hexapod volumes almost ceased), Svensk Insektfauna (publication ceased), Fauna Entomologica Scandinavica (an English-language ‘replacement’ for the two preceding series), Danmarks Dyreliv, Handbooks for the Identification of British Insects and Tierwelt Deutschlands. A national tool for finding identification literature, is Lomholdt, O., Nielsen, P. & Schnack, K. (ed.) 1984: Entomologisk Litteratur - en hjælp til studiet af den danske insektfauna. Ent.Meddr 51(1-2), 85 pp. A few newer identification manuals are mentioned in the following notes. But otherwise reference can be made to the immensely useful bibliographical tool by P. Barnard (ed.): Identifying British Insects and Arachnids. An Annotated Bibliography, Cambridge University Press 1999. An important modern guide to identification of freshwater insects is a two-volume manual edited by A.Nilsson: Aquatic Insects of North Europe. A Taxonomic Handbook. 1-2, Apollo Books, 1996- 1997. There are still large sectors of the NW European hexapod fauna for which no useful identification manuals are available, notably in the Diptera and parasitic Hymenoptera. Hopefully an ambitious Swedish ‘Nationalnyckel’- initiative will lead to this situation being remedied within the next couple of decades.

GENERAL ANATOMY AND PHYSIOLOGY SAE chapters 1, 2, 6 Chapter 6 bears very strong marks of the author’s personal views. These make for stimulating reading, but they are partly controversial! (For critique, see, e.g., Bitsch, Ann. Soc. Ent. France 30: 103-129, 1994; rebuttal by J-PK in her contribution to the above-mentioned Arthropod Relationships (R. A. Fortey & R. H. Thomas eds, 1997).

Segmentation, body regions (SAE: 4 ff). A body segment is by some morphologists conceived as a structural unit, which is so well-defined that one can meaningfully draw (on the basis of musculature, innervation etc.) a “map” of the course of individual segment boundaries in those body regions (head and tail ends) in which the segment limits not are obvious; see below. There is no evidence that the tracheal system in hexapods was segmentally arranged in the head region and the abdominal apex, and traces of a segmentation of the anterior or posterior portion of the dorsal vessel, if they were ever present, must have become lost at a pre-hexapod level. Some morphologists have suggested that some hexapods have traces of thoracic ‘intersegments’ (understood as incompletely developed segments) between the conventionally (and easily) recognized ones; this remains controversial, however.

The head and its appendages (SAE 5 ff, 138 ff.). The SAE account (4, 138) of the hexapod head as being composed of six segments (proto-, deuto- and tritocerebral, plus mandibular, maxillary and labial segments) complies with the probably most widely accepted interpretation, but it is not the only one. One of the alternatives is shown in Fig 1 here. It recognizes the presence of a “tetrocerebral” segment located between the mandibular segment and the tritocerebral (the appendages of which are always strongly reduced/transformed in all myriapods and hexapods – represented perhaps by the labrum, see below). The term clypeus should be reserved for the part of the head capsule, which accommodates the origins of those sucking pump dilator muscles that will insert outside the loop formed by the connectives from the frontal ganglion to the tritocerebrum (SAE fig. 1.8). Defined in this way the clypeus can often not be externally delimited from the frons by sulci on the head capsule (a sulcus running between the anterior tentorial pits will sometimes prove to be transclypeal).

4 The morphological nature of the labrum is controversial. It has long been widely considered to belong, at least largely, to the tritocerebral segment (as indicated by its innervation); recent gene- expression work has brought new support to previous proposals that it represents fused limbs of this segment. Is it, then, non-homologous with the labrum in Crustacea (in which the tritocerebral- segment limbs are the 2nd antennae)?? The articulation between the head capsule and the mandible is of considerable interst in the question of the first splitting event identifiable within the Insecta. A ‘new’ anterior mandibular articulation has long (SAE 8, 122) been considered a synapomorphy of the Zygentoma [sølvkræ- gruppen] and the Pterygota, cp. the name Dicondylia. However, in both Zygentoma and Ephemeroptera (mayfly [døgnflue]) nymphs there are actually two anterior mandibular articulations (with the clypeus and the base of the anterior tentorial arm, respectively), but the connection remains fairly loose in both groups. A close contact between an area on the anterior mandibular surface and the head capsule in the anterior tentorial pit region actually occurs also in Archaeognatha and some entognathans, though one can here hardly talk about a genuine articulation. This close contact could be plesiomorphic at the hexapod level. It has been suggested (Koch, in Deuve, ed, 2001) that the anterior mandibular articulation is secondarily reduced in Archaeognatha, as indicated by the presence here of a complement of extrinsic mandibular muscle bundles that is smaller than that ascribed to the hexapod ground plan. Bitsch (Ann. ent. Soc. France (NS) 37: 305-321, 2000) argues that the shape and the anterior cranial connection of the zygentoman/ephemeropteran mandible is indeed an intermediate stage between the mono- and dicondylous types. In any case a truly firm dicondylous articulation between the head capsule and the mandible (whereby the mandibular movement is restricted to a transverse swing around the axis between the two articulations, making for a strong bite) is a putative synapomorphy of the Odonata (dragonflies [guldsmede]) and Neoptera). In the posterior (ancestral) articulation a mandibular condylus [ledtap] fits into a cranial ginglymus [ledgrube]; in the anterior articulation (the neoformation things are reversed. Besides large cranial ab- and (particularly large) adductor muscles the mandible primitively has also a ventral adductor that originates from the tentorium and, in the most basal taxa (cp. Fig 2 here, and SAE 122: DICONDYLIA) also on the connective-tissue endoskeleton; this ventral adductor is reduced or completely lost in many advanced insects. The ‘superlinguae’ (SAE 8) are by some morphologists considered vestigial appendages on the ‘tetrocerebral’ segment (see above).

The limbs (SAE 11 ff, 136 ff) of hexapods are usually described as 'uniramous'. Note, however, the small stylus near midlength of the coxa in Archaeognatha (SAE 242, fig. 14.1F,C). In Palaeozoic fossil pterygotes Kukalová-Peck (SAE chapter 6) has identified what appears to be segmented appendages arising from the joint membranes between a number of the basal limb segments (inclusive of a 'subcoxa' located proximad from the coxa and apparently homologous with the pleuron in modern pterygotes), and she interprets the wing as a corresponding 'exite' on an even more proximal limb segment, the 'epicoxa', which like the subcoxa has become incorporated in the lateral body wall. The concept of the pleural sclerites being derived from a proximal limb segment has actually long been widely accepted. A 'prefemur' and a 'patella' have similarly been claimed to be identifiable in these old fossils, but there is no general agreement among 'neo-entomologists' that such segments must be ascribed to the ground plan of the hexapod limb. The same is true for the recognition of the most proximal tarsomere ('basitarsus') as something basically different from the following. The trochantin (SAE fig. 1.11A) is presumably a sclerite split off from the coxal margin. The pretarsal lobes/processes such as 'pulvilli', 'arolium' and 'empodium'(SAE 11 and fig. 14B) apparently do not pertain to the insect ground plan; they only evolved within the Pterygota.

5 Thorax (SAE 9 ff). In pterygotes the pterothorax (sometimes the prothorax as well) often has the pleuron and sternum anteriorly fusing into a 'precoxal bridge' (as shown in SAE fig. 1.11A). It may, then, be difficult or impossible to decide how much of the ventral plate is actually pleural; some insect morphologists even believe that all anterior 'tergosternal' muscles in most pterygotes actually are morphologically tergopleural.

The wings (SAE 12ff, 140ff) are formed in the dorsolateral body wall, in the boundary region between the pleural and tergal territories, and they undoubtedly comprise at least some elements of the former. Kukalová-Peck's theory of the derivation of wings from a limb-base-exite has gained considerable, though not unanimous acceptance. In addition to the criteria mentioned in SAE (14-15) for vein homologization - and of these the tracheisation criterion is known to be quite unreliable, at least in higher insects - also the articulations of the principal veins with the wing base sclerites can be an aid to establishing vein homologies in the basal wing region. While interpretations of the wing base in the most primitive fossil pterygotes and the extant 'palaeopteran' orders is difficult (and remains controversial), the wing articulation in neopterans is practically always compatible with the model shown in SAE fig 1.17C. The '2nd axillary' [axillare 2] is a very complex formation comprising sclerotizations in both the upper and the lower wall of the wing; its ventral part articulates with the pleural wing process [vingetap]. It should be noted that the wing base is one of the body regions that is most difficult to study, particularly in small and weakly sclerotized/melanized insects.

Flight (SAE 44-45). Fig. 3 here shows diagrammatic cross-sections of the pterothorax in pterygotes with different flight motors.

Abdomen [bagkrop] (SAE 17 ff, 142 ff). Strongly reduced, but still segmented limbs have by Kukalová-Peck been identified on the abdomen of (both nymphs and adults of) pterygotes belonging to extinct palaeopteran groups (SAE chapter 6, fig. 6.10). In some Palaeozoic primarily wingless inscts (Monura, a group with debatable status) the cerci were, in her interpretation, short and had paired apical claws (fig. 6.9A)! The 'gonangulum', a sclerite in the ovipositor base (SAE 19) has primarily articulations with '1. valvulae', '2. valvifer' and the anterior corner of tergum IX; this sclerite is here shown in Fig 4.

Integument (SAE 25 ff). A couple of different chemical pathways may lead to the 'sclerotization' [sklerotisering] of the cuticle, i.e., to the formation of the hard exocuticle (SAE 27) through formation of cross-links between cuticle proteins. Sclerotization is not necessarily accomapnied by a darkening of the cuticle although that is most often the case. NOTE: the classical expression "strongly chitinized" for particularly hard and/or dark cuticle is in any case misleading, in as much as these properties are in no way related to the amount of chitin present. A technical note: Unlike other tissues the cuticle is not dissolved upon immersion (and even boiling for a moderate length of time) in KOH. KOH maceration is therefore widely used for making cleared preparations of, e.g., genitalia segments or heads with mouthparts for taxonomic or morphological study. Unsclerotized cuticle may be stained with several histological stains, whereas exocuticle is refractory to stain, presumably because of the dense 'packing'og cuticle material. Endocuticle below the exocuticle may show staining properties different from that of procuticle in adjacent membranous regions; this is the explanation why staining may often lead to improved differentiation between 'sclerites' and 'membranes'.

6 The small protuberances of the exoskeleton, including sensilla (SAE 35-39) are often important in systematic research. A 1979 review article by Richards & Richards (Int. J. Insect. Morphol. Embryol. 8: 143-157) remains a most useful reference. In addition to the types mentioned in SAE the so-called 'acanthae' should be mentioned; these are (sometimes quite large) processes formed by just a single epidermal cell; hence they are devoid of a socket.

Endoskeleton (SAE 10, 27). At least in primitive hexapods one finds endoskeletal structures that are not invaginations from the body wall, but are genuine connective tissue formations of presumably epidermal origin. These include the "ligamentous endoskeletal plates" between primitive mouthpart muscles mentioned in SAE chapter 5 (DICONDYLIA, p. 122 ff); the median formation (bearing many muscle insertions) above the suboesophageal ganglion in fig, 5.3 is an example.

Tracheal system (SAE 31 ff). Spiracular closing devices are said (SAE 31) to be present in “most insects”, while in the phylogeny chapter (SAE 123) closer muscles inserting directly on sclerites in the abdominal spiracles are considered a possible synapomorphy of Odonata [guldsmede] and Neoptera (in adult Ephemeroptera [døgnfluer] the tracheal trunks just inside the spiracles are closed through being compressed by body wall muscles). Intriguingly, however, muscles inserting directly on the abdominal spiracles have actually been reported also from some, but not all, Zygentoma (Rousset Int. J. Insect. Morphol. Embryol. 2: 55-80, 1973); a parallelism? The closing devices of the spiracles are obviously an adaptation to ‘advanced terrestrial life’. In the case of apterygote hexapods that live in moist microhabitats water loss through the spiracles is no serious hazard. Closing devices are secondarily lost in many advanced pterygotes (immatures in particular) that live in moist habitats. Spiracles cannot all be serially homologous, since the thorax in the Diplura may have more than one pair per segment (SAE 240). Barlet (1988, Bull. Ann. Soc roy Belge Ent. 124: 171-187) has suggested that hexapod spireacles pertain to no less than four series; the criteria for the identification of these need renewed scrutiny, however.

Nervous system and associated endocrine organs (SAE 34 ff). If one recognizes the presence of a tetrocerebral segment in the hexapod head, then the recognition of a ‘tetrocerebrum’in the cephalic central nervous system (in front of the mandibular domain in the suboesophageal ganglion.) is a corollary. The frontal ganglion (SAE figs 1.8 og 2.17) is primitively connected not only to the tritocerebrum, but also has a nervous connection to the protocerebrum; this ‘nervus connectivus‘ has been lost independently on more occasions in higher insects. Corpora cardiaca (SAE 42 og fig. 2.17) are very small in Archaeognatha and entognathans (may be entirely lacking in collembolans and Diplura-Campodeidae, but that may well be secondary loss); in all hexapods they are closely associated with the aorta wall, and are sometimes continuous with the later. Corpora cardiaca have on more independent occasions become fused into a median formation. Corpora allata (SAE 42 and fig. 2.17, not named; the c.a. is the round organ issuing fine nerves and united to the corpus cardiacum by a strong nerve) are in Diplura-Campodeidae og apterygote insects distant form the c. cardiaca, but have convergently in other entognathana and in pterygote insects become closely approached to the latter. Primitively they are innervated from the suboesophageal ganglion, but this innervation is lost on independently more occasions within higher inscts.

Sensory organs (SAE 35 ff). It is noteworthy that the sensory neurons in hexapod mechanorecep- tors (including auditory organs) and chemoreceptors (SAE 37-39) have, in the distal process, a formation, which (as shown by its ultrastructure) is derived from a cilium.

7 Circulation (SAE 52 ff). In cockroaches [kakerlakker] and mantids [knælere] there are in some segments lateral arteries from the dorsal vessel. It would be straightforward assumption that such arteries are a highly plesiomorphic feature, but they are unknown form other hexapods, hence they are apparently an autapomorphy of the cockroach+mantid group, or more likely, the Dictyoptera as a whole, and sekundarily lost in termites.

Female reproductive system (SAE 54 ff). In addition to the diversity outlined in SAE it maay be noted, that in some insects the female genical chamber ansatomoses with the rectuam, forming a cloaca on the terminal true segment (morfologically segment XI). In the1990s there has been some focus on the the fundamental difference between the sac-like ovaries in Collembola, Protura and Diplura-Campodeina on one hand and the metameric/'postmetameric' ovariole arrangement in Diplura-Japygina and the Insecta s.str. on the other. 'Out-group' comparisons with other arthropods indicate that the last-mentioned configuration actually should be interpreted as the apomorphic one – a kind of paedomorphosis (Stys, Zrzavý & Weyda 1993. Biol.Rev. 68: 365-379).

Ontogenesis. (SAE 56 ff). The egg-cleavage pattern described is probably not plesiomorphic in Hexapoda. It has long been known that the primarily apterous, entognathan Collembola have an initially complete cleavage,i.e., the first daughter cells of the zygote are separated by complete cell membranes and only later is a superficial blastoderm formed as in other Hexapoda (Fig. 5 here). Interestingly enough it is now known that the Archaeognatha also have a (brief) initial phase of complete cleavage.

The apterygote hexapods For cladistic relations on 'ordens'- and higher levels see SAE 119-122. As noted above a purely superficial egg cleavage may constitute an additional synapomorphy of Zygentoma and Pterygota. As noted by Štys et al. (cp. above) the ovariole structure might suggest that Diplura-Campodeina are the sister group of Collembola+Protura and/or that the Diplura-Japygina are the sister group of the Insecta s.str. But note the (conflicting) evidence for dipluran monophyly below.

DIPLURA SAE 121, 240-241 The monophyly of the Diplura is not strongly supported in the SAE account, but the above- mentioned ovariole characters are the first recognized weighty counterarguments. However, a specific similarity (known since long, but largely overlooked) in the mouth apparatus of the campodeid- og japygid assemblages (an interlocking of the superlingua and the maxillary galea) should be noted as an apparently strong (!) dipluran autapomorfi; the same may be true of the position of the gonopore (immediately behind sternum VIII) in both sexes (Kristensen 1997, in the Arthropod Relationships, R.A.Fortey & R.H.Thomas eds). The specific similarities in leg morphology and movements in campodeids and japygids mentioned by Manton (cp. SAE 121) need re-investigation. The "moniliform antennae, with intrinsic muscles in the flagellar segments" (SAE 240) are evidently a plesiomorphy at this level. As mentioned above, it is uncertain whether the 2 extra thoracic spiracles in JAPYGIDAE are an autapomorphy (the sister family PARAJAPYGIDAE only has the ordinary 2) or represent a plesiomorphic additional ‘series’ of spiracles. Only the family CAMPODEIDAE is represented in N. Europe (a couple of species).

8 ELLIPURA (= Protura + Collembola) "Linea ventralis", the peculiar furrow on the lower head surface which seems to be a ‘strong’ synapomorphy of Protura and Collembola, is illustrated Fig. 6 here.

PROTURA SAE 121, 238-239 The spiracles in EOSENTOMOIDEA (families EOSENTOMIDAE and the E Asian SINENTOMIDAE) occur on the meso- and metathorax. The non-tracheate proturans are assembled in the superfamily ACERONTOMOIDEA. A few species in N. Europe, both main groupings being represented here.

COLLEMBOLA, springtails [springhaler] SAE 121, 233-237 The swing of the furca during jumping is a movement primarily due to locally increased blood pressure in the abdominal cavity. Concerning egg cleavage: see above under Ontogenesis. The diagnostic feature of the "suborder Arthropleona" is evidently a plesiomorphy, hence the group is unlikely to be monophyletic. The Symphypleona-lineage constitutes just a minor part of the order. The spiracle in the neck region is unique, indicating that the tracheal system has evolved independently from that of other hexapods (alternatively it might be a ‘reversal’ from an ancestral, longer series of spiracles, which is largely reduced in extant Hexapoda). There are a few hundred species of collembolan species in N. Europe. Many of the arthropleonan collembolans pertain to a superfamily ENTOMOBRYOIDEA, which is characterized by the delimitation of the pronotums being obsolete. Important recent literature. Hopkin, S.P. 1997: Biology of the springtails. 330 pp. Oxford University Press.

ARCHAEOGNATHA [klippespringere] SAE 122, 242-244 and ZYGENTOMA (=THYSANURA s.str.), silverfish etc. [sølvkræ-gruppen] SAE 122, 245-247

PTERYGOTA The question of the ‘basal split' within the winged insects is discussed SAE 123-124. The argument from mandibular structure (see above) for the monophyly of Odonata+Neoptera has been emphasized recently; in contrast, rDNA data (Wheeler et al. Cladistics 17: 113–169, 2001; Hovmøller, Pape & Källersjö Cladistics 18: 313-323) support ‘palaeopteran’ monophyly.

EPHEMEROPTERA, mayflies [døgnfluer] SAE 124, 248-253 Note the paired male copulatory organs and female gonopores in the ordinal ground plan. In Danmark about 40 species.

ODONATA, dragonflies [guldsmede] SAE 124, 254-261 The ‘suborder’ ZYGOPTERA (damselflies [vandnymfer]) has been considered paraphyletitic in terms of ANISOPTERA [egl. guldsmede], but it may actually be monophyletic. The small Asiatic genus Epiophlebia has ‘zygopteran’ traits in ving morphology, but the body design and nymph morphology is anisopteran-like; it is usually placed in a high-rank taxon of its own, ANISOZYGOPTERA. Most Danish ‘vandnymfer’ pertain to the family COENAGRIIDAE, while the largest and most strikingly coloured (the males have blue-pigmented wings) are in the AGRIONIDAE. Our largest

9 anisopteran families are AESHINIDAE (common large species in Aeshna) and LIBELLULIDAE (large, stout-bodied taxa in Libellula, moreover some genera with smaller and more slender members). Altogether about 50 odonatans occur in Danmark, 30+ being anisopterans. Ole Fogh Nielsens information-rich and beautifully illustrated De danske guldsmede, Apollo Books, 1998 is the main national reference.

Lower Neoptera, or 'orthopteroid' orders SAE 124 As expounded in SAE 124 the phylogenetic relations between these orders are difficult to resolve Kukalová-Peck's optimistic, largely resolved phylogeny (SAE chapter 6, later elaborated on in Can. J. Zool., 70: 2452-2473, 1992 and Syst. Ent. 18: 333-350, 1993) is controversial (Kristensen Zool. Beitr. 36: 83-124, 1995). A 'total evidence' analysis of insect phylogeny on the basis of rDNA and morphological characters (Wheeler et al., Cladistics 17: 113-169, 2001) ends up with a somewhat resolved phylogeny of the lower neopterans, which (perhaps surprisingly) here constitute a monophyletic entity: ((Plecoptera + Embiotera) + (Phasmatodea + Orthoptera)) + (Dermaptera + Grylloblattodea + Zoraptera + Dictyoptera); however, the morphological dataset used in that analysis is much in need of revision. An analysis of a smaller, but more reliable morphological dataset (Beutel & Gorb, J. zool. Syst. Evol. Res. 39: 1-31, 2001) does find the assemblage of lower neopteran orders to be paraphyletic in terms of the Paraneoptera and Endopterygota. The recently described Mantophasmatodea may be most closely related to the Grylloblattodea; this suggestion, initially made on the basis of the foregut sclerotization, has ben supported by subsequent molecular findings.

ORTHOPTERA= SALTATORIA [græshopper] SAE 126, 290-296 The characteristic orthopteran jumping mechanism, an extension of the femur-tibia joint, is paralleled in, e.g., the so-called flea beetles ([jordlopper] a subordinate lineage within the Chrysomelidae [bladbiller]). In contrast, the great majority of other jumping insects the jump is due to a rotation of the trochanter relative to the coxa – the same movement by which winged insects take off for flight. The two generally recognized suborders are ENSIFERA [løvgræshopper i videre forstand] with the superfamilies Gryllacridoidea, Tettigonioidea and Grylloidea [fårekyllinger]) and CAELIFERA [markgræshopper] including the rest. Some Orthoptera systematists have insisted that the Ensifera and Caelifera should be treated as distinct orders, but the question remains whether the Ensifera are paraphyletic in terms of the Caelifera. Probably the best argument for ensiferan monophyly is a peculiar tooth arrangement in the posterior (proventricular [tyggemave]) section of the fore gut. The ensiferan ovipositor has a uniquely apomorphic structure, in as much as the 3. valvulae (normally a protective sheath around functional ‘shaft’ comprising the interlocked 1st and 2nd valvulae) here are integrated in the ‘saw’-shaft itself, being also interlocked with the 1st valvulae., se Fig. 7 here. However, the caeliferan ovipositor (SAE fig. 1.24D) is so pronouncedly autapomorphic (the short valvulae are free from each other and can perform outward-directed digging movements), that it is difficult/impossible to decide whether it has been derived from a primitive the ‘ensiferan-type’ ovipositor. There just above a dozen ensiferans in Denmark, most belonging to TETTIGONIIDAE, including two large green Tettigonia species and the spotted-winged Decticus verrucivorus [vortebideren]; probably the most frequently observed species is the smaller Meconema thalassinum [egegræshoppen]. GRYLLIDAE ('fårekyllinger") are represented in our fauna by the introduced Acheta domestica [husfårekyllingen], (Gryllus campestris ([markfårekyllingen] is known from Bornholm, but has not been found here for many years now) and GRYLLOTALPIDAE by Gryllo- talpa [jordkrebs].

10 Denmark is home to about 20 califerans; most belong to ACRIDIDAE, three to TETRIGIDAE [torngræshopper]. Ole Fogh Nielsen’s De Danske Græshopper (Apollo Books, 2000) is an information-packed and superbly illustrated account of our orthopterans.

DICTYOPTERA s.lat. cockroaches [kakerlakker], termites [termitter], mantids [knælere]; treated in SAE as 3 distinct 'orders' Blattodea, Isoptera, Mantodea SAE 125, 266-283 As noted SAE p. 125 the interrelationships between the three phenetically quite distinctive dictyopteran groups remain debatable, but the bulk of the presently available evidence supports that the cockroaches are indeed paraphyletic in terms of the termites – and the composite group is, then, the sister group of the mantids (Deitz et al. Ent. Abhandlungen 61: 69-91, 2003) The Australian Mastotermes darwiniensis is unique among termites in having retained a distinct hind wing vannus (SAE fig. 20.1E) and all 5 tarsomeres. It is most likely the sister group of all other extant termites. This time-honoured view has been challenged in the early 1990s, but is supported in a more recent analysis of termite phylogeny based on a sizable morphological data set (Donovan et al., 2000, Biol. J. Linn. Soc. 70: 467-513). In N. Europe only cockroaches are represented; 3 species of Ectobius occur in nature, all others (less than a dozed regularly occurring) are introduced.

PHASMATODEA, stick and leaf insects [vandrende pinde og blade] SAE 126, 297-301 Do note that the elongation of the meso- og metathorax are not phasmatodean ground plan specializations of the order: its most basal extant members have ordinary body proportions. The order is un-represented in N. Europe. Mapping the presence/absence of wings on a recent phylogeny of the Phasmatodea led to the conclusion that wings were absent in the ordinal ground plan (Whiting et al. Nature, 421: 264-267, 2003).the presence of wings in subordinate lineages must accordingly be interpreted as a character reversal.

EMBIOPTERA (EMBIIDINA), webspinners SAE 126, 302-305 The order is un-represented in N. Europe, but a few species occur in the Mediterranean

GRYLLOBLATTODEA (=NOTOPTERA), ice (or rock) crawlers SAE 125, 284-285 The order is un-represented in Europe.

MANTOPHASMATODEA, heel-walkers (unmentioned in SAE) The discovery of the Mantophasmatodea in 2002 (Klass et al., Science 296: 1456-1459) was a source of some excitement in the entomologists’ community; the last finding of an insect that clearly proved un-assignable to a recognized ‘order’ was in 1914 (Grylloblatta). Adult mantophasmatodeans (Fig 11 here) are about 2 cm long and completely apterous. Females are immediately separable from generalized stick-insects by the lack of a venter VIII ‘operculum’: concealing the base of the short ovipositor, and by the absence of defensive glands discharging on the pronotal fore corners. The pronotal margins are not produced posteriorly and laterally, hence unlike in orthopterans there is no prothoracic ‘cryptopleury’. The cerci are stout and unsegmented, strongly curved in males. The male sternum IX bears a posteromedial process. All five tarsal segments are discernible, though the basal three are synscleritous; the arolium is very large. The proventricular section of the fore gut has a cuticular armature strongly reminiscent of that in Grylloblattodea. A sister-group relationship between the two orders is also supported by recent molecular evidence (forthcoming publication from M. Whiting group, Brigham Young University).

11 About a dozen species are currently named. All so far recorded extant taxa are from the Afrotropics, most are from S. Africa/Namibia, but one single specimen of a distinct species is from Tanzania. However, a Baltic amber (Eocene) fossil insect almost certainly also belongs to this order, which, then, previously must have had a more extensive range. Mantophasmatodeans are carnivorous, catching small arthropods with their somewhat spiny fore- and middle legs. They owe their vernacular name to their habit of lifting the tarsal apex from the substrate (the alternative vernacular name ‘gladiator’ appropriate applies only to a few spiny-bodied species).

PLECOPTERA, stoneflies [slørvinger] SAE 124-125, 263-265 The nymphs of our Plecoptera can be immediately distinguished from those of mayflies [døgnfluer] by their lack of the median terminal filament. A short filament does occur in some non.European stonefly nymphs (and nowehere else among extant neopteran insects), but is perhaps an autapomorphic neoformation rather than a plesiomorphy. Adult stoneflies eat lichens or algae, or they do not feed at all. 25 species have been found in Denmark, but some of these are believed now to have become extinct here during the 20th century (running-water animals are vulnerable!); this may be true, e.g., of the largest species recorded from the country, Dinocras cephalotes.

ZORAPTERA SAE 127, 306-307 The bionomics of the group is overall poorly known, and so is its morphology and its phylogenetic affinities. Zorapterans are one of the great challenges of present-day systematic entomology! Tropical, including part of the USA; absent from the Palaearctic region and Australia.

DERMAPTERA, earwigs [ørentviste] SAE 126, 286-289 5 species occur in Denmark, Forficula auricularia being by far the most common and familiar; in spite of its well-developed hind wings it extremely rarely flies.

PSOCODEA: Psocoptera+Phthiraptera SAE 127-128, 308-315 Probably the most important synapomorphy of "Psocoptera" and Phthiraptera is a complement of peculiar sclerotizations on the hypopharynx, shown here in Fig. 8: Paired ovoid ’lingual sclerites’ are connected to the socalled ’sitophore’ sclerotization (on the hypopharyngeal base) by narrow sclerotized grooves (here foming an inverted Y). This is known to be a device for water-uptake: a hygroscopical film of saliva (i.e., a secretion from the labial glands) may cover the lingual sclerites and here absorb water from the atmosphere; the cavity in the centre of the sitophore fits a knob on the ceiling of the preoral cavity, and when this knob is lifted (by contraction of the sucking pump dilators originating on the clypeus on the anterior surface of the cranium) the resultant vacuum draws fluid from the lingual sclerites through the delicate sclerite grooves. There is now good evidence that the ’Psocoptera’ are indeed paraphyletic in terms of the parasitic lice. This certainly makes sense from an evolutionary-ecological perspective. Note, for instance, that loss of wings is characteristic of some ’psocopterns’, and also that a number of these live in nests of mammals and birds. PTHIRAPTERA (lice in the broad sense) comprise 4 lineages: 1) AMBLYCERA, characterized by rather short, clavate antennae which are concealed in a groove on the lower surface of the head capsule. Comprise both mammal and bird parasites. Habitus SAE fig. 29.1I.

12 2) ISCHNOCERA. The antennae are not clavate (but some segments may bear, often sexually domorphic, processes) and are somewhat longer than those of the Amblycera. The mouthparts are downwards-directed. Likewise comprise both mammal and bird parasites. 3) RHYNCHOPHTHIRINA. Just one genus Haematomyzus, habitus Fig. 9 here. Head capsule produced into a snout with apically situated mandibles. The latter can perform outwards directed movements (and their abductors are more powerful than the adductors) and anchor the louse in the host skin. The best known species H. elephantis on elephants (both African and Indian!), the two other on African pigs (warthog and bush-pig, respectively). 4) ANOPLURA (= Siphunculata’, sucking lice) are characterized by strongly modified mouth parts. SAE mentions the presence of three stylets in the anopluran mouth apparatus, but this is an oft-repeated error based on preparation artefact; there are actually only two. The anterior/dorsal stylet (largely formed by the hypopharynx) has on its posterior/loswer wall a tubular sector, which serves the outlet of saliva; during the preparation of histological sections this sector usually becomes disassociated from the other part of the stylet. The host blood is sucked up through the concave dorsal surface of the anterior stylet. Derivatives of both the mandibles and maxillae are recognizable in the base of the moth apparatus (Ramcke: Zool. Jb. Anat. 82: 547-663, 1965). About 30 species free-living psocodeans (i.e., ‘psocopterans’) are known from Denmark, and a somewhat higher number of the parasitic forms, but neither has been the subjected to long-term targeted investigations. The study of the Danish fauna of parasitic lice is an excellent subject for ‘hobby-research’ for biologists – particularly for those who take an active interest in entomology as well as birds/mammals!!!

THYSANOPTERA [blærefødder, thrips] SAE 128, 330-333 As noted in SAE the females of some taxa have retained a rather typical ovipositor, while in the majority of the thysanopterans it is lost. This was the basis for the conventional subdivision of the two suborders TEREBRANTIA and TUBULIFERA, but the monophyly of the Terebrantia can, of course, not be upheld on the basis of this plesiomorphic character state. Less than 100 species of thrips have so far been recorded from Denmark , but the total number present here may be around 150.

HEMIPTERA [næbmundede] SAE 128, 316-329 The morphological interpretation of the stylets pertaining to the mandibular as well as the maxillary appendages is controversial; the same is true for the plate-like folds from the head capsule, which conceal the stylet bases. Particularly noteworthy details in the internal anatomy include the telotrophic (=acrotrophic) ovarioles and the ‘filter-chambers’ which have been independently evolved on more occasions in plan-sucking lineages (‘short-circuits’ between the fore-and hind end of the midgut, serving rapid elimination of water from the ‘thin solutions’ of nutrients; revisit SAE p. 49 and fig. 2.43). The Hemipter are in SAE grouped into 4 ‘suborders’1: 1) STERNORRHYNCHA. A striking autapomorphy is the stongly backwards flexed head capsule: the proboscis seemingly originates between the forelegs. The wing venation is always more or less simplified. The are four main lineages; all are cosmopolitan and their members are plant- suckers:

1 A taxon ’Homoptera’ comprising the non-Heteroptera was abandoned by phylogenetic systematists some 30 years ago (it is based on its members’ usually un-specialized forewings, hence a plesiomorphy) but is still retained in several general texts.

13 PSYLLOIDEA, jumping plant lice, [bladlopper]. Superficially similar to small plant- or leafhoppers, but the forewing venation is characteristic: a ’tree’ with a single stem. About 50 species in Denmark. ALEYRODOIDEA, mealy bugs [mellus]. Body and wings whitish due to a ’powder’ of wax particles. Wing venation extremely reduceded (SAE fig. 30.4D). Only few species known from Denmark. APHIDOIDEA, aphids [bladlus] is a truly successful group in the northern temperate regions (in N. Europe about as species-rich as the Heteroptera), but it is poorly represented in the tropics and the temperate regions of the S. Hemisphere. APHIDIDAE s.str. i.e., the aphids that have siphunculi [rygrør] (paired tubular structures on abdominal segment V, visible as short, stout cone-like formations in SAE fig.30.10, but often much more prominent; they give off alarm pheromones) and whose parthenogenetic females are viviparous, are by some authors treated as a superfamily with several families; they comprise the vast majority of out aphids. The family ADELGIDAE (that fomr ananas galls [ananasgaller] on conifers) are more generalized than other aphidoids in having retained an ovipositor. Many aphids have great economic importance through damage caused by their sucking and by their transmission of plant diseases. COCCOIDEA, scale insects [skjoldlus] are, on a global scale somewhat more species rich than the aphids, and their representation in the tropics is much more larger. Less than 100 species are known from Denmark. The N. European scale insect fauna is another obvious subject for ‘hobby research’! Like the aphids the coccoids have many members that are of economical importance. 2) 'AUCHENORRHYNCHA' [cikader2]. Putative auchenorrhynchan autapomorphies include the antennal structure (flagellum reduced, a bristle-like formation) and the sound-producing apparatus (paired specialized regions in the lateral body wall in the abdominal base are drawn inwards through the contraction of powerful muscles, and they ‘return’ due to elasticity). All ‘auchenorrhynchans’ are plant suckers. Two principal clades are recognizable, FULGORO- MORPHA and CICADOMORPHA. Important families in the former are DELPHACIDAE (planthopppers, with a prominent ’spur’ on the hind tibia), and FULGORIDAE (with the large ’lantern flies’ in S. America, famous for the enlarged and bizarrely shaped head capsule; not represented in N. Europe). Important cicadomorphan families include CICADIDAE ([sangcikader], not in Denmark; only males ‘sing’, but these are the only ‘auchenorrhynchans’ whose sounds are audible to the unaided human ear, CERCOPIDAE ( froghoppers [skumcikader], with a few species in N. Europe, some of which may be extremely abundant) and CICADELLIDAE (lefhoppers; in N.Europe one of the most dominant insect groups in herbaceous vegetation. Delphacidae and Cicadellidae both include serious agricultural pests. Ca 300 species of ’auchenorrhynchans’ are known from Denmark. In recent years the monophyly of Auchenorrhyncha has been questioned, because details in the wing and male genitalia structure of Fulgoromorpha can be interpreted as indicating a sister-group relationship to Coleorrhyncha+Heteroptera; the proposal has subsequently been supported also by molecular evidence (e.g.,. Campbell et al., Syst.Ent. 20: 175-194, 1995). If it is indeed correct, the specialised antennal morphology and the sound producing organs must have been evolved independently in fulgoromorphans and cicadomorphans. 3) COLEORRHYNCHA. A single family, PELORIDIIDAE, with circum-antarctic range (austral S.America., Australa, New Zealand etc.); ca 30 species. Plant suckers, all living in moist bryophytes. Small, flattened insects (SAE fig. 30.11A) with a broad head capsule and horizontal pronotal folds; fore wings thickened, with coarse venation, hind wings most often reduced, but fully winged specimens do occur in some species.

2 Til danskerne/For the Danes: "Cikader" bruges på dansk for ALLE 'auchenorrhyncher', iøvrigt ligesom 'Zikaden' på tysk; men engelsk har IKKE nogen fællesbetegnelse for disse dyr: en 'cicada' er en sangcikade.

14 4) HETEROPTERA, ’true’ bugs [tæger3]. While the most species rich subgroups are plant suckers the most generalized lineages are carnivorous, and this life-style is usually presumed to be ancestral within the Heteroptera. The ‘proboscis’ base is forwards directed (but the proboscis itself is bent in repose, so that its apex is pointing backwards) and related to this modification the head capsule is posteriorly (topographically ventrally) closed by a sclerotization. Another autapomorphy is a well developed system of metathoracic stink glands in the adult (nympgs have another gland complement in the abdominal dorsum). In contrast, the characteristic ‘hemelytra’ [halvdækvinger] are presumably not an autapomorphy of the Heteroptera as a whole. There are about 500 species of Heteroptera in Denmark. The true bugs are classified into several ’infraorders’, the interrelationships of which have been debated. It is likely that the ENICOCEPHALOMORPHA (small tropical/subtropiscal-cosmopolitan group) and the GERROMORPHA (cosmopolitan, the ’semiaquatic’ bugs) are the most basal lineages: they do not have the specialized ‘hemelytra’ and this is presumably a genuine plesiomorphy. Among the semiaquatic bugs (eight families, half of them represented in Denmark) adaptations for movements on the free water surface has been evolved independently on more occasions; in the large family GERRIDAE, water striders [skøjteløbertæger] the genus Halobates includes half a dozen species adapted for life on the open oceans! NEPOMORPHA are the water bugs [vandtæger] in the strict sense. They include the CORIXIDAE [bugsvømmere], NAUCORIDAE such as Naucoris [rygsvømmerne], Ilyocoris [vandrøveren ] and the wingless plastron-bearing Aphelocheirus [vandvæggelus] and the NEPIDAE including, e.g. Nepa [skorpiontæge] and Ranatra [stavtæge]. CIMICOMORPHA and PENTATOMORPHA comprise the bulk of the true bugs. CIMICOMORPHA include a number of carnivore lineages, of which we in Denmark have representatives of, i.a., ANTHOCORIDAE, CIMICIDAE (bed bugs [væggelus], bldod sucking on bats, birds – and humans), NABIDAE and REDUVIIDAE; the last mentioned include, e.g., the harmless Reduvius personata [støvtæge] and the important experimental insect Rhodnius prolixus (of S.American origin), which, with other members of the family, are important disease vectors. Plant sucking cimicomorphans include TINGIDAE [masketæger] and theparticularly large family MIRIDAE [blomstertæger] comprising ca. 2/3 of our native heteropterans. The PENTATOMORPHA include plant suckers in the family LYGAEIDAE [frøtæger] and the well- known PENTATOMIDAE [bredtæger/stinktæger]. Important recent literature. W.R. Dolling 1991: The Hemiptera. 274 pp. The Natural History Museum & Oxford University Press.

Superorder ENDOPTERYGOTA [inskter med fuldstændig forvandling] SAE 128 ff The Endopterygota comprise more than 80% of all insects. Their principal synapomorphy is the unique larva whose eyes (almost always small groups of simple eyes, ’stemmata’) are broken down at metamorphosis, and whose rudiments of wings and external genitalia are located in epidermal pockets below the cuticle, SAE fig. 2.55B. The final immature stage, the pupa, is comparable to the final immature instar of non-endopterygotes, but is specialized in always being inactive, non- feeding. The metamorphosis, and the commonly used descriptive terms for the various pupal types is treated in SAE pp. 58-59. It must be emphasized that the more or less profound metamorphosis in

3 Til danskerne/For the Danes: Navnet "tæger" bruges stadig i vide kredse om flåter, altså midefamilien Ixodidae. Det har utvivlsomt også været den oprindelige hovedbetydning af ordet: flåter hedder ticks på engelsk og Zecken på tysk. Men på norsk har tæge-navnet været brugt om de - ligeledes blodsugende - heteropterer Cimex (som vi nu kalder væggelus), og det er tilsyneladende herfra, navnet blev indført for insektgruppen i 'officielt' dansk zoologsprog omkring 1770.

15 some subordinate paraneopteran groups (SAE 325, 331) are a morphological/physiological parallelism of endopterygote metamorphosis, not a phylogenetical forerunner of the latter. As mentioned below the placement of the Strepsiptera within the Endopterygota is debatable, but the monophyly of the group otherwise appears well supported.

STREPSIPTERA [viftevinger] SAE 128, 360-364 In the most primitive extant Strepsiptera the females are apterous, but they do have legs and compound eyes, and they are free-living (SAE fig. 36.2A), as is the final larval instar. They pertain to the small family MENGENILLIDAE (Mediterranean, China, Australia) and they parasitize zygentomans. As mentioned SAE 128 some Strepsiptera have pharate late juvenile stages with external wing rudiments. Moreover, the larval eyes reportedly are taken over unchanged by the adults. These facts are the basis why the placement of the group within the Endopterygota has been questioned. It remains debated, however, whether the external wing rudiments are indeed a strepsipteran ground plan feature. If the Strepsiptera are indeed endopterygotes, a sister group relationship to the beetles is a possibility: possible synapomorphies are the flight mechanism (’posteromotorism’, i.e., only the hind wings are true organs of flight) and the large size of the thoracic sterna (which are larger than the terga). Putative beetle/strepsipteran synapomorphies in the structure of the wings and wing base (Kukalová-Peck & Lawrence 1993, Canad.Ent. 125: 181-258) were rejected byWhiting & Kathirithamby (1995, J.N.Y.ent.Soc. 103: 1-14), but this controversy remains unfinished (Kukalová- Peck, pp. 249-268 in Fortey & Thomas eds Arthropod Relationships, Chapman & Hall 1997). A radical innovation of the discussion about strepsipteran relationships is the proposal by Whiting, Wheeler and their coworkers (1994, Nature 368: 696; more detailed accounts Syst .Biol. 46: 1-68, 1997 & Cladistics 17: 113-169, 2001) that they are the sister group of the Diptera. This proposal is based on similarities in 18S og 28S rDNA, but morphological arguments are also provided, and – most remarkably – an argument from developmental genetics: the strepsipteran thorax is derived from a Dipteran-type thorax through a 'homeotic mutation' which has interchanged meso- og metathorax! The strength of both the molecular and the morphological evidence remains debated, (Kristensen, Eur. J. Entomol. 96: 237-253, 1999, and references therein). The strepsipteran fauna of Denmark remains largely unstudied; only a couple of species (in the planthopper/bee/wasp parasitizing taxa) have been recorded from the country.

NEUROPTERIDA [netvinger s.lat.] SAE 129, 334-344

RAPHIDIOPTERA, snakeflies [kamelhalsfluer] and MEGALOPTERA, are both small orders, each with a couple of hundres species. The former is a purely northern-hemisphere group (2-3 species in Denmark) and is extremely homogeneous. The latter comprises the family SIALIDAE [dovenfluer] with 3 species in Denmark, and the CORYDALIDAE (including, i.a., the large American ’dobson flies’). The sister group relationship between raphidiopterans and megalopterans is now questioned (Aspöck, Mitt. Dtsch. Ges. allg. angew. Ent. 10: 633-636, 1995; Aspöck et al. Ent. Abhandlungen 61: 157-158, 2004); the proposal has been made that the Neuroptera s.str. are the closest relatives of the Megaloptera, and that the aquatic life-style is primitive also in the former. The problem arguably remains open. In a very recent molecular (18S rDNA) analysis the Megaloptera come out paraphyletic in terms of the other Neuropterida (Winterton, Ent. Abhandlungen 61: 158-160, 2004). NEUROPTERA s.str. (= Planipennia) are represented in Denmark by 6 families with altogether >50 species, most of them in the families CHRYSOPIDAE [guldøjer] and HEMEROBIIDAE [florvinger]; our 3 species of MYMELEONTIDAE [myreløver] all have very restricted ranges.

16 COLEOPTERA, beetles [biller] SAE 129, 130, 345-359 Comprises about one fourth of all described organisms, but in N. Europe it is surpassed – by far – by flies as well as wasps. The composition of the Danish beetle fauna must be considered very well known. An annual updating of the excellent Danish beetle catalogue from 1996 (M.Hansen ed.) now shows now >3.700 species. Four beetle suborders are currently recognized: two very small ones, the moderately large ADEPHAGA and the enormous POLYPHAGA. Their mutual relationships have been much debated. A recent analysis pf an extensive morphological data set (Beutel, R. & Haas, F. 2001) supports the phylogeny Archostemata + (Adephaga + (Myxophaga + Polyphaga)). The non- archostematans ('Pantophaga') are characterized by simplifications in the thoracic skeleton and musculature; the Myxophaga and Polyphaga share a specialized larval leg (only two segments distad from femur, consistently unpaired claws). The non-polyphagan beetles share a characteristic hind wing venation, with a so-called "oblongum", an elongate/ovoid oblique cell which at both ends is closed by what is interpreted as a M-Cu crossvein, SAE fig. 35.3D-E; moreover, there is a hinge on vein Cu just proximad from the oblongum. These venational characteristics are presumably plesiomorphic at the coleopteran level. ARCHOSTEMATA. Un-represented in N. Europe. Best known family CUPEDIDAE (about 20 species), characterized by peculiarly pitted and scaly elytra, which sometimes are interpreted as plesiomorphic (derived from a wing with a fine-meshed reticulate venation; similar wings are known from Permian deposits. The larvae live in rotten wood. Two additional, very small families. MYXOPHAGA. Four species-poor families comprising tiny beetles that live in fresh water or moist soil. Algal feeders. In Denmark represented by Microsporus acaroides (family Microsporidae). ADEPHAGA. Autapomorphies are a firm connection between the pronotum and the propleuron, as well as a fsion of the hind coxae with the metasternum and the 2nd abdominal sternum (sternum I is completely reduced), which they thereby ‘divide’, SAE fig. 35.4A. The suborder comprises about one-tenth of all beetles, globally as well as in N. Europe. Several families of adephagans are often recognized, but it is most likely that the large family CARABIDAE, ground beetles [løbebiller] as usually delimited are paraphyletic in terms of many of the other. In N. Europe the aquatic adephagans are represented by the GYRINIDAE, whirligig beetles [hvirvlere], HALIPLIDAE, NOTERIDAE and DYTISCIDAE [egl. vandkalve] which were previously collectively talked of as 'Hydradephaga', but they are not a monophylum. The Adephaga are now believed to have invaded fresh water 3-4 times independently. CARABIDAE in the strict sense comprise the 'typical’ ground beetles (ca. 300 speces in Denmark), autapomorhic groups like the CICINDELINAE , tiger beetles [sandspringere] with 4 species in Denmark and PAUSSINAE (exotic; myrmecophilse that feed ants by secretions given off from, i.a., the thickened antennae). Most are carnivorous both as larvae and well as adults, but herbivores do occur. POLYPHAGA. Autapomorphies of this enormous group include, i.a., the prothoracic ’cryptopleuron’ (the pleuron, which is fused to the trochantin, is covered by the pronotum) and the telotrophic (=acrotrophic) ovarioles (parallelism to Hemiptera and some Neuropterida!). The classification of the Polyphaga is very difficult; one recognizes some 20 superfamilies grouped into ‘series’. Only few of these higher taxa have easily recognizable autapomorphies. Some important taxa are: HYDROPHILOIDEA including, e.g. HYDROHILIDAE [vandkærer]. STAPHYLINOIDEA with, e.g. SILPHIDAE [ådselsbiller] and the STAPHYLINIDAE [rovbiller], with usually short elytra and the hind wings complexly packed below the latter; in N. Europe this is the most species-rich animal family (>900 species in Denmark). SCARABAEOIDEA [torbister] with characteristically lamellate antennal apices include LUCANIDAE [hjortebiller; ‘eghjorten’

17 Lucanus cervus the largest native beetle in Denmark, now believed to be extinct here), GEOTRUPIDAE [skarnbasser] and SCARABAEIDAE [gødningbiller, oldenborrer, guldbasser, næsehornbiller m.m.]. BYRRHOIDEA include terrestrial taxa as well as families with aquatic members such as ELMIDAE (with plastron respiration, SAE 33 and fig. 2.14) in adults. ELATEROIDEA including, i.a., ELATERIDAE [smældere], CANTHARIDAE ([blødvinger]; the adults are among the most conspicuous diurnal beetles in N. Europe, on flowers and foliage) and LAMPYRIDAE [Sankt Hansorme] with luminescent organs in adults as well as larvae, females wingless. BOSTRICHOIDEA include serious household pests in the families DERMESTIDAE [klannere] and ANOBIIDAE [borebiller & tyvebiller]. CUCUJOIDEA include NITIDULIDAE [glimmerbøsser] and COCCINELLIDAE (ladybird beetles [mariehøns]). TENEBRIONOIDEA are the 'heteromerous' beetles; the name alludes to the fact that the tarsi have different segment numbers: fore –and mid-tarsi have 5, hind segments 4; they include, e.g., the TENEBRIONIDAE [skyggebiller], MELOIDAE [oliebiller m.m.] and PYROCHROIDAE [kardinalbiller]. CHRYSOMELOIDEA and CURCULIONOIDEA constitute an immensely successful lineage, almost exclusively comprising herbivorous members. A possible synapomorphy is the ‘kryptopentamerous' tarsi (SAE fig.35.8D): the 4th tarsomere is tiny and seen from below it is completely concealed by the large bilobed 3rd tarsomere. The former include the CERAMBYCIDAE (longhorn beetles [træbukke]] and the CHRYSOMELIDAE (leaf beetles [bladbiller]], the latter (weevils [snudebiller]) a suite of families of which CURCULIONIDAE (with about 50.000 known species) is the largest family in the Animal Kingdom; the bark [barkbillerne] SCOLYTINAE, are now considered a subordinate curculionid lineage. Important recent literature: Beutel, R. 1997 Über Phylogenese und Evolution der Coleoptera (Insecta), insbesondere der Adephaga. Abh. naturw. ver. Hamburg (NF) 31, 164 pp. Beutel, R & F. Haas. 2000. Phylogenetic relationships of the suborders of Coleoptera (Insecta). Cladistics 16:103-141.

HYMENOPTERA SAE 130, 132, 406-418. One of the largest insect orders. At least in N. Europe it is the largest, with >7000 species The retention in the Hymenoptera of an ovipositor with all typical elements is a unique plesiomorphy at the endopterygote level (cp. SAE fig. 5.6 and 42.4A-B). The SAE systematic account has two hymenopteran ‘suborders’: ‘Symphyta’ (sawflies) and Apocrita (waist-wasps). The former ['plantehvepsene'/'blad- og træhvepse'] is clearly paraphyletic in terms of the latter. Among its members may be mentioned the XYELIDAE, a small family which in some characters is more primitive than any other Hymenoptera (the fore wing has a forked Rs and the pupa has movable mandibles – hence it is untrue that hymenopteran pupae are consistently adecticous, as stated SAE 412); it is represented in Denmark by Xyela julii. Moreover TENTHREDINIDAE (comprising the majority of our non-apocritans), CIMBICIDAE (large, robust insects with clubbed antennae), and SIRICIDAE [træhvepse] with wood-boring larvae. ‘Typical’ free-living sawfly larvae (SAE fig 42.5A) are superficially similar to ‘typical’ lepidopteran caterpillars, but have more pairs of abdominal prolegs (on abdominal segments II-VIII, X, lepidopterans only on III-VI, X), and these have never crochets; moreover, the larval eyes on each side form a small compact group covered by a common corneal lens (lepidopteran caterpillars usually have 6 separate simple eyes on each side. The sister group of the Apocrita is the family ORUSSIDAE, whose larvae in contrast to those of other ‘symphytans’ are not herbivores but parasitoids - on larvae of wood-boring beetles and siricids. This beautifully fits the scenario one would a priori propose for the origin of the Apocrita. It is a small family (< 100 species) whose members are rarely observed; none of the European species are recorded from Denmark.

18 The monophyly of the APOCRITA [stilkhvepsene] is convincingly supported by the petiole [hvepsetaille] (SAE 410-411), and by the larval midgut being non-continuous with the hindgut; the larvae are consistently legless. The overwhelming majority of the apocritans, and hence of the hymenopterans (by us ca 5/6 of the members of the order) have larvae that are parasites (or better: 'parasitoids', because the hosts are almost always killed) in other insects. The predominately parasitoid families are often talked of collectively as the 'Parasitica' [snyltehvepse], but this assemblage is almost certainly not a monophylum. It includes a suite of superfamilies including the'megadiverse' ICHNEUMONOIDEA (small to middle-sized, very rarely large insects; larvae usually parasitoids in insect larvae) and CHALCIDOIDEA (small to tiny insects, larvae often parasitoids in insect eggs). The latter also does comprise herbivorous members, and so does the superfamily CYNIPOIDEA, which include gall-formers [galhvepse]. The representation of the 'Parasitica’-families in Denmark is overall very poorly known – excellent topics for biologists’ ‘hobby-research’! The taxa which in SAE are talked of as the superfamilies CHRYSIDOIDEA, VESPOIDEA, SPHECOIDEA and APOIDEA together constitute the clade ACULEATA, characterized by apomorphic details in the structure of the ovipositor, and not least its function: it only works as a ‘sting’ [giftbrod], and no longer plays any role in ovipositon (the female gonopore is located in front of the ovipositor base). CHRYSIDOIDEA including, i.a., CHRYSIDIDAE [guldhvepse] (often predators on larvae of solitary bees and wasps) and DRYINIDAE (parasitoids of leaf- and planthoppers) are perhaps the sister-group of the remaining Apocrita; unlike in the latter the sting apparatus is not completely concealed within abdominal segment VII. VESPOIDEA including, i.a., MUTILLIDAE [fløjlsmyrer] (females wingless, larvae mostly predators on larvae of other aculeate Hymenoptera), POMPILIDAE [vejhvepse] (larvae in chambers in soil, provisioned with spiders), SCOLIIDAE, (ectoparasites on coleopteran larvae, in the tropics including some of the largest hymenopterans), VESPIDAE [gedehamse] (characterized by the capacity of folding their wings longitudinally, include both solitary and social taxa) and FORMICIDAE, ants [myrer] (all social, about 50 species in Denmark). APIDAE s.lat. (SAE: overfam. APOIDEA), the bees, are apparently cladistically subordinate in the SPHECOIDEA/SPHECIDAE, digger wasps [gravehvepse]; the ground plan autapomorphies of the APIDAE are the body ‘fur’ (secondarily lost in non-pollen-gatherers) and the broad, flat proximal tarsus segment on the hind legs. There are about 120 species of digger wasps in Denmark, and probably about twice as many bees (a modern check-list is highly desirable!). True sociality has been evolved >10 times independently within the Hymenoptera-Aculeata, and only very few times elsewhere in the animal kingdom (among insects notably termites and some Thysanoptera). It has been pointed out, that the special sex determination mode of Hymenoptera, haplodiploidy4, may have favoured evolution of sociality because female hymenopterans share more genes with their sisters [(1 x ½) + (½ x ½) = ¾ - if the mother has mated just once] than with their own offspring (½). Important supplementary literature: Gauld, I. & Bolton, B. (eds.) 1988 (& later reprints): The Hymenoptera. British Museum (Natural History) & Oxford University Press, 332 pp. Goulet, H. & Huber, J.T.S. (eds) 1993: Hymenoptera of the World. An Identification Guide to Families. Agriculture Canada, Research Branch. A special issue of Zoologica Scripta 28(1-2) 1999 brings a lot of pertinent information on Hymenoptera evolution.

4 For the Danes/til danskerne: med HAnlig HAploidi

19 MECOPTERIDA ('panorpoid' groups) The possible monophyly of Mecopterida + Hymenoptera (SAE 130) may apparently be supported by the fact that adults in both groups have a completely sclsrotized plate in the floor of the sucking pump. In the plesiomorphic condition there is just a sclerotized rod in each side of the pump; this condition is retained in neuropterids and beetles (Kristensen, Eur. J. Entomol. 96: 237-253, 1999).

ANTLIOPHORA SAE 131-132 The close relationship between scorpion flies and fleas have in recent years been supported by molecular data. It is even suggested, that the fleas may be just a subordinate group within the scorpion flies. The putative morphological ground plan autapomorphies of the latter (SAE 132) therefore need renewed scrutiny.

MECOPTERA, scorpion flies [skorpionfluer] SAE:132, 365-368 Scorpion flies are immediately separable from the neuropterids by their paucity of cross veins behind the costal margins of the fore wings. The basal segment of the 2-segmented appendage (’gonopod’) on the male abdominal segment IX is strongly swollen; the diameter of the immediately preceding segments are in some families markedly tapering and upwards bent, and these two specializations together account for the ’scorpion-tail’-like abdominal tip to which the group owes its vernacular name. In contrast to other small endopterygote orders such as Raphidioptera, Megaloptera and Strepsiptera the Mecoptera are strikingly diverse. Note that the larvae have retained compound eyes (which, however, reportedly are broken down at metamophosis and reconstructed de novo as in other endopterygotes) and, probably in the ground plan, also a median ocellus; both conditions are unique plesiomorphies at the endopterygote level. Of the 9 extant families the following shall be mentioned: NANNOCHORISTIDAE (<10 species, circum-antarctic). The only mecopterns with aquatic larvae; these are carnivorous and very different from other scorpion fly larvae (SAE fig. 37.3E-G). Adult nannochoristids have some plesiomorphies in the structure of the genital segments, which set them apart from other mecopterans; also the adult’s head capsule is, unlike that of other scorpion flies, not pronouncedly produced into a ’snout’. The Nannochoristidae have, like the following family and the fleas an ovariole type, which can be interpreted as being secondarily panoistic. Do these groups together constitute a monophylum? (Simiczyjew, Acta Zoologica 83: 61-66, 2002). BOREIDAE, snow fleas [snelopper] have reduced wings as adults. Moss-feeders, one species in Denmark. This is the family which in some molecular analyses come out as the sister group of the fleas. BITTACIDAE are mostly large, long-legged insects. The adults are predators, the larvae (as in most mecopterans) soil animals. Almost cosmopolitan, but absent from N. Europe. PANORPIDAE include the majority of the scorpion flies; there are a few species in Denmark. The adults are mostly scavengers, some being renowned for their ability of grasping dead insects from spiders’ webs. The families MEROPEIDAE (one species in N.Am. and one in Australia!) and EOMEROPEIDAE (= NOTIOTHAUMIDAE, one species in S. America) have been subject to particular interest. These insects have broad wings with a densely reticulate venation, Fig. 10 here. This feature was long considered to be plesiomorphic, and the two families were placed in a separate suborder ("Protomecoptera"). However, judging from the genital segments in both sexes the two are not each closest relatives, and at least the Eomeropeidae apparently belong to a subordinate clade that comprises neither the Nannochoristidae, the Boreidae and the Bittacidae. The wing morphology of the two families may therefore be considered specialized – and independently so.

20 Many fossil insect wings from the Permian onwards have been assigned to the Mecoptera, but they may as well belong to other lineages within the Mecopterida: the Mecoptera have no known ordinal autapomorphies in the wing structure! Important literature Willmann, R., 1989: Evolution und Phylogenetisches System der Mecoptera (Insecta, Holometabola). Abh. senckenberg. naturforsch. Ges. 544, 153 pp. Also Willmann’s Mecoptera chapter in the new (2004) edition of the insect ’Kästner’, mentioned in the introduction.

SIPHONAPTERA (lopper) SAE 132, 369-373 See above under Mecoptera. About 50 species are known from Denmark, but our native fauna of these insects has only been sporadically studied.

DIPTERA [tovingede] SAE 132, 374-387 The Diptera have fewer described species than the Coleoptera and Lepidoptera; in N. Europe it is, however, with >6000 second only to Hymenoptera. And one would arguably describe it as the most diverse of the large endopterygote orders. What is called in SAE the hypopharynx in the dipteran mouth apparatus is actually a formation peculiar to the order, the ‘lonchus’ [spytklingen], which, as shown by it containing the salivary duct, is a morphologically composite formation comprising a hypopharyngeal and a prelabial element. NOTE: The Diptera classification in SAE is conservative, non-phylogenetic (Don Colless has been a prominent proponent of phenetic systematics). Of the three ‘suborders’ recognized the 'Nematocera' ([myg]. With unspecialised antennae, SAE fig 39.1G-I – the name Nematoceraa means “thread-horn”), paraphyletic in terms of the BRACHYCERA [egl.fluer]. The Brachycera are mostly more robuste than the nematocerans, the antennae are shortened and the basal flagellomere often enlarged. However, in the ground plan of the Brachycera antennal structure is still unspecialised. An important autapomorphy is a rotation of the larval mandibe plane of movement: the anterior articulation lies mediad from the lateral, and the mandibles hence are no longer moved toward each other, but in parallel planes. The brachyceran group 'Orthorrhapha' is paraphyletic in terms of the CYCLORRHAPHA, whose autapomorphies are the ‘typical fly antenna’ (SAE fig. 39.1J), the puparium and the ‘maggot’ larva which is devoid of head capsule and has a complex mouth apparatus ('cephalopharyngeal-skeleton', SAE fig. 39.6C). The morphological interpretation of the elements of the latter is controversial (in SAE the ‘mouth hooks’ are considered mandibular, but judging from their ontogenetic development they also include significant components from the maxillary segment). Finally it appears that the 'Aschiza' are paraphyletic in terms of the SCHIZOPHORA; the autapomorphy of the latter is the ptilinum ['pandeblære' ] (SAE 374), which during eclosion is evaginated by blood pressure and serves to open the ’lid’ of the puparium; after eclosion it is withdrawn (by means of a muscle) and leaves a scar ['pandespalte'] above the antennae (visible as an inverted V in SAE fig. 39.1A). Among the nematoceran families - in N.Europa comprising about 1/3 of the dipteran species – the following should be mentioned: TIPULIDAE [stankelben], CULICIDAE [stikmyg], CHIRONOMIDAE [dansemyg], CERATOPOGONIDAE [mitter], SIMULIIDAE [kvægmyg], BIBIONIDAE [hårmyg] og MYCETOPHILIDAE [svampemyg]; the CECIDOMYIIDAE [galmyg] with >600 N. European species is our largest dipteran family, and its representation in Denmark is very poorly investigated. Among the non –cyclorrhaphan brachyceran flies the following may be mentioned: STRATIOMYIDAE [våbenfluer], TABANIDAE [klæger], RHAGIONIDAE [sneppefluer], ASILIDAE [rovfluer], THEREVIDAE [stiletfluer], BOMBYLIIDAE [humlefluer], EMPIDIDAE

21 [dansefluer] and DOLICHOPODIDAE [styltefluer]; the two last-mentioned are apparently among the closest relatives of the Cyclorrhapha. Noteworthy among the very numerous families within the successful CYCLORRHAPHA are the families SYRPHIDAE (hover flies [svirrefluer]) and PIPUNCULIDAE [øjefluer]; both are 'aschizans', hence devoid of a ptilinum. Moreover TEPHRITIDAE [båndfluer], AGROMYZIDAE [minerfluer], DROSOPHILIDAE (fruit flies [bananfluer], including the celebrated Drosophila melanogaster), BRAULIDAE [bilus], SCATHOPHAGIDAE [møgfluer], ANTHOMYIIDAE [blomsterfluer], MUSCIDAE (with Musca domestica [stuefluen]), CALLIPHORIDAE [spyfluer], SARCOPHAGIDAE [kødfluer], TACHINIDAE [snyltefluer], GASTEROPHILIDAE [bremser], GLOSSINIDAE [tsetsefluer], and HIPPOBOSCIDAE [lusefluer]. The Danish fauna of Diptera is very unevenly investigated. Next to the parasitoid Hymenoptera some dipteran families represent the most serious lacunae in the knowledge of our national insect fauna. An interesting recent checklist recorded documented Danish occurrence of 4.361 species, but estimated a total exceeding 5.850 (Petersen & Meier, Steenstrupia 26: 119-276, 2002). Other important recent literature: McAlpine, J.F. et al. (ed.) Manual of Nearctic Diptera. Vol. 1, 1981; vol. 2, 1987; vol. 3, 1989. Research Branch, Agri-culture, Canada, Monograph No. 27. Papp, L. & Darvas, B. (eds). Contributions to a Manual of Palaearctic Diptera. 1-4, 1997-2000.

AMPHIESMENOPTERA SAE 132

TRICHOPTERA (vårfluer) SAE 132, 388-394 The two large superfamilies recognized in the SAE system are apparently both monophyla: INTEGRIPALPIA s.str. (= Dicloacia, = Limnephiloidea s.lat.). Larvae hypognathous, case- building. Include, e.g., the PHRYGAENIDAE (with the largest Danish caddisflies) and LIMNEPHILIDAE (the most species-rich caddisfly family, globally and in Denmark). ANNULIPALPIA (=CURVIPALPIA, = Hydropsychoidea s.lat.). Larvae prognathous, usually net/retreat-spinning. Adults with the apical segment of the maxillary palp elongated and annulated. In contrast, it remains uncertain how the remaining four overall generalized families should be classified. Some consider them to constitute a monophylum, 'SPICIPALPIA' (SAE's 'RHYACOPHILOIDEA', but the assemblage is more likely paraphyletic in terms of one or both of the large lineages. The four are RHYCOPHILIDAE (and its S-Hemisphere counterpart HYDROBIOSIDAE; both have prognathous, free-living and carnivorous larvae), GLOSSOSOMATIDAE (‘saddle-case’ makers) and HYDROPTILIDAE (the smallest caddisflies, larvae initially free-living, later ‘purse-case’ makers). Less than 200 caddisfly species are known from Denmark. Important supplementary literature: Frania, H.E. & Wiggins, G.B. 1997: Analysis of morphological and behavioural evidence for the phylogeny and higher classification of Trichoptera (Insecta). Royal Ontario Museum Life Science Series 160: 1-67.

LEPIDOPTERA [sommerfugle] SAE 132, 395-405 Lepidopteran evolution is summarized in the diagram given in in Fig. 12. Note that ca 98-99% of all Lepidoptera belong to the monophylum DITRYSIA, characterized by a specialized female genital apparatus with separate openings for copulation and oviposition (SAE 399 and fig. 41.5D;

22 incidentally, fig. 41.5C is misleading, in as much as the ductus bursae should originate from the ‘vagina’ dorsad from the ovaries, not ventrad as shown). The remaining assemblage of overall primitive lepidopterans comprises numerous species-poor lineages, which have arisen in a sequence of evolutionary ‘splitting events’ in which one ‘typical lepidopteran apomorphy’ has been evolved after the other. The basal diversification mode of the Lepidoptera is overall well understood – it has some similarity to that of the Hymenoptera (with the Ditrysia being a counterpart of the Apocrita). In the three most basal lineages the adults have retained primitive biting mouthparts. MICROPTERIGIDAE [urmøl] (cosmopolitan, <200 known species, 7 in Denmark) as adults feed on pollen or fern spores; the larvae are moisture-requiring ‘soil animals’ feeding on detritus, fungus hyphae or liverworts [levermosser]. They are the only extant family of Lepidoptera in which non- dependence on flowering plants may be the primitive condition. AGATHIPHAGIDAE (2 known species, Australia, SW pacific) have larvae mining in seeds of kauri pin, Agathis; as many endophytic larvae they are legless (SAE fig. 41.6G). Pupal mandibles hypertrophied (SAE fig. 41.6J). It is unknown whether the adults feed at all. HETEROBATHMIIDAE (9 known species, temperate S.America) have larvae that are leaf miners in Nothofagus [sydbøge]; the adult moths presumably feed on pollen in the same trees. This group shares some striking specializations (including the prominent Y-shaped strengthening lines on the larval head capsule SAE fig. 41.6A: 'adfrontal suture') with the Glossata; these are presumably true synapomorphies. All the remaining Lepidoptera belong in the monophyletic GLOSSATA, characterized by very prominent ground plan autapomorphies. Most important are is the adult’s sucking proboscis formed by the maxillary galeae (SAE 395, fig. 41,1A,B,F), while the mandible is reduced and only serves the movement of the pupal mandibles for opening the pupal shelter. Also the larval spinneret (SAE 399 and fig. 41.6A) is a glossatan groundplan autapomorphy. The most basal glossatan grade is represented by the ERIOCRANIIDAE, a small, purely Holarctic family (8 species in Denmark) whose larvae are legless leaf miners in trees pertaining to the Fagales (mostly Betula and Quercus). In the next ‘splitting events’ identifiable in the Recent fauna (some small non-European families) additional specializations are acquired, including the hollow wing scales (SAE 396, fig. 41.4C,F) and an intrinsic proboscis musculature, serving a firm coiling; even the short proboscis of the lowest Glossata is coiled in repose, but that is due exclusively to the elasticity of the galea wall. The NEOLEPIDOPTERA are characterized by important modifications in the immature stages: the larvae acquire those crochet-bearing, musculated abdominal prolegs on III-VI og X (SAE figs 41.6B-D, F-I), that are so characteristic of most Lepidoptera caterpillars. The pupae become 'obtect' [mumiepuppe] and 'adecticous' [ikke-bidende] ; hereby the adults’ mandibles completely loose any role and become strongly reduced. The first differentiated Recent Neolepidoptera-group, EXOPORIA (represented in Denmark by HEPIALIDAE [rodædere]) have a strongly autapomorphic female genital apparatus (Fig. 13 here): as in the DITRYSIA (presumably convergently) there are separate openings for copulation and oviposition, but the two systems have no internal connection; after copulation the sperm travels in a gutter from the 'bursa' opening to the ovipore and thence to the genital chamber/spermatheca. The HETERONEURA are characterized by the fore-and hind wings having markedly different venation: the hind wing Rs is unbranched. Moreover, the hind wings are by various means (examples in SAE fig. 41.3D, D) coupled to the fore wings. Roughly one-half of the ditrysians are overall small insects whose larvae live concealed (between folded/spun leaves, or as leaf-, stem, fruit-miners) and have retained the primitive arrangement of the proleg crochets (in circles). Together with the non-ditrysians these are collectively known as 'microlepidopterans' (or just ‘micros’) [småsommerfugle]. This assemblage include large superfamilies as TINEOIDEA (with TINEIDAE [‘egl møl’] many of which feed on fungi, and some

23 on unusual substances such as keratin, hence they comprise some well known textile pests), YPONOMEUTOIDEA, GELECHIOIDEA, TORTRICOIDEA [viklere], PYRALOIDEA (with tympanic organs in the abdominal base) and small, but remarkable families like SESIIDAE [glassværmere] of which many are wasp mimics, and PTEROPHORIDAE [fjermøl] whose mostly deeply divided wings are a very unusual condition in the winged insects. ZYGAENOIDEA- ZYGAENIDAE [køllesværmere] have larval prolegs with crochets in ‘mesoseries’ ['klamrefødder'] see below; these are presumably evolved independently of those in the Macrolepidoptera. The remaining ditrysians are termed Macrolepidoptera [storsommerfugle]. Their larvae are overall more freely exposed, and the proleg crochets are arranged in a single median row (‘mesoseries’, SAE fig. 41.6D). They may constitute a monophylum. Important lineages include the HESPERIOIDEA+PAPILIONOIDEA, butterflies [dagsommerfugle]; BOMBYCOIDEA with BOMBYCIDAE (the silkworm moth Bombyx mori), SATURNIIDAE [natpåfugleøjer] and SPHINGIDAE, hawk moths [aftensværmere]; GEOMETROIDEA-GEOMETRIDAE [målere] have a tympanic organ in the abdominal base, while the NOCTUOIDEA including the NOCTUIDAE [ugler] have tympanic organs in the metathorax. ARCTIIDAE (tiger moths [bjørnespindere]) and LYMANTRIIDAE [penselspindere] are perhaps just subordinate lineages within the Noctuidae, which (even in a more restricted sense) is the largest family of Lepidoptera. Tympanic organs have been evolved independently in several ditrysian lineages (not only those mentioned above). They are known to register bat echolocation sounds, and it is likely that those moth lineages whose ground plan comprises a well developed tympanic organ have evolved later than the origin of the bats (around the Cretacous/Tertiary boundary??).

FIGURE LEGENDS Fig. 1. 'Map' of segmental composition in the head of a dicondylian insect, according to one of the proposed theories. 1 proto-, 2 dento-, 3 trito-, 4 'tetrocerebral' segments, named after the corresponding sections in the brain; 5 mandibular-, 6 maxillar-, 7 labial segment, named after the corresponding segmental limbs; 8 prothoracic sector of 'postocciput'. After Chaudonneret.

Fig. 2. (Oblique) transverse section of an archaeognathan head. On top frontoclypeus (clFr), pharynx and the tritocerebral sector of the brain (Tcr). Note the two connective tissue (‘ligament’) masses (ltm & ltmx) on which some mandibular (adm 1) and maxillary (adast, advst) adductor muscles originate. TA is the anterior (cuticular or ’tue’) tentoria larm. MSOE, suboesophageal ganglion, cexm salivary canal. After Bitsch.

Fig. 3. Schematic cross-sections of wined segments in A, a dragonfly; B, a 'typical' pterygote; C, neopteran (such as a cockroach) with reduced indirect wing muscles. Wing levators with straight, wing depressors with wavy linies. F ('fulcrum') the pivot of wing movement. After Boudreaux.

Fig. 4. Abdominal segmentsVIII-X in a female silverfish (ZYGENTOMA) seen from inside, strongly diagrammatic. GA 'gonangulum' sclerite (not shown in the corresponding figure, 1.23C in SAE) articulating with 1. gonapophysis (1Gpo, = gonapophysis VIII); note also the articulation of the gonangulums to tergum X and '2.valvifer' (2Gx, =[gono]coxite IX); 1 & 2Gs (gono)stylus on segment VIII and IX; 1Gx '1, valvifer’; T, tergum. After Scudder.

Fig. 5. Early egg cleavage in a collembolan; note the total cleavage in the beginning phase (A). Eventually a superficial blastoderm (F:b) is formed, as usually in Hexapoda (SAE 56). After Jura.

24 Fig. 6. Head of a proturan, from below. LV is the 'linea ventralis', seen in transverse section below. After Francois.

Fig. 7. Ovipositor of an ensiferan grashopper, transverse section. 'Dorsal valve ' is the distal part of 2. valvifer (=3.valvula); 'Inner valve' is the gonapophysis on IX (=2.valvula); 'Anterior valve' is the gonapophysis of VIII (=1.valvula). After Davies

Fig. 8. Hypopharynx of a 'psocopteran'. After Badonnel.

Fig. 9. Facies of ’elephant louse’, Haematomyzus (Psocodea-Phthiraptera); note the snout-like head capsule. After Weber.

Fig. 10. The richly reticulate wing venation of the extant member of Mecoptera-Eomeropeide. After Willmann.

Fig 11. Mantophasma zephyra facies (top), female genital segments, lateral (lower left), male genital segments lateral (lower right) C: coxite; cc: cercus; ep: dorsum XI (‘epiproct’); gp, gonapophysis; pp, (paired) venter XI (‘paraprocts’); S: sternum; sp: sternal process; T: tergum. Klaus-D. Klass del.

Fig. 12. Cladogram of lepidopteran superfamilies. Width of individual clade-lines indicate approximate number of described species, where these have species numbers >1000). Original.

Fig. 13. Female genital apparatus of exoporian moth. an, ‘antrum’ (lepidopterist jargon for sclerotized posterior end of bursa copulatrix); bc, bursa copulatrix; gc, genital chamber; gs, gland on spermatheca; il, intergenital lamella (flanking sperm groove); la, ‘lamella antevaginalis’, sclerotized lower lip of copulatory opening; ob, copulatory opening; oc, common oviduct; ol, lateral oviduct; op, ovipore; re, rectum; sp, spermatheca. Original.

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