The sperm pumps of Strepsiptera and Antliophora (Hexapoda)

Male genital structures of representatives of Strepsiptera, Siphonaptera and Diptera are described in detail, with special emphasis on sperm pumps. The parts involved in the apparatus are evaluated with respect to their homology. Functional interpretations are presented based on the morphological observations. The phylogenetic significance of characters related to the male genital apparatus is discussed. The sperm pumps differ strongly in Strepsiptera and Antliophora (s.s.) and are not homologous. The strepsipteran type, which lacks any sclerotized parts, has evolved independently. Autapomophies of the male genital apparatus are the compact testes, the large balloon‐shaped vesicula seminalis, the strongly developed musculature of the proximal ductus ejaculatorius, the strongly simplified copulatory organ, the unusual muscles of segments VIII and IX, and the complete absence of accessory glands. The median fusion and almost globular shape of the vesicula are potential autapomorphies of Corioxenidae. The absence of the furrow separating the testes from the vesicula seminalis is a derived condition found in Xenos and Myrmecolax. A sperm pump is absent in Boreus (Mecoptera) and Culicomorpha and the functionally relevant parts and their arrangement differ strongly in Siphonaptera, Pistillifera and Diptera (excl. Culicomorpha). The presence of a functional and homologous pumping apparatus does not belong to the groundplan of Antliophora, which implies that this alleged autapomorphy of the clade is invalid. A sperm pump belongs to the groundplan of Diptera and was secondarily reduced in Culicomorpha, many representatives of Bibionomorpha, and in Diopsidae. It was very likely primarily absent in Mecoptera. However, the precise reconstruction of the groundplan depends on the position of Nannochoristidae within Mecoptera and on the possible affinities of Siphonaptera and Boreidae. Sperm pumps should be considered as a functional term and not be used as a character for phylogenetic reconstruction, unless specific similarities are included in the character definition.     

The head of Merope tuber (Meropeidae) and the phylogeny of Mecoptera (Hexapoda)

External and internal features of the head of adults of Merope tuber were examined and described in detail. The results were compared to conditions found in other members of Mecoptera and other antliophoran lineages. A list of characters of different body parts and life stages is presented. The parsimony analysis and a recent evaluation of thoracic features suggest a basal placement of Merope within monophyletic Pistillifera. The monophyly of Mecoptera was not supported by our data set. Nannochoristidae (Nannomecoptera) was placed as sistertaxon of a clade comprising Diptera and Siphonaptera. Cephalic features supporting this group are modifications of the mouthparts linked to feeding on liquid substrates. Considering recent results of extensive morphological and molecular investigations we consider this placement of Nannochoristidae and the implied mecopteran paraphyly as a possible artefact. Potential cephalic autapomorphies of Mecoptera are the presence of a tooth-like projection of the gena and a prepharyngeal tube, the absence of M. frontolabralis, and the origin of M. tentoriooralis on the middle region of the anterior tentorial arm. Despite of the conspicuous morphological differences between Caurinus and the other boreid genera the family forms a well supported clade. A sistergroup relationship between Boreidae and Pistillifera is confirmed. A unique synapomorphy is the presence of specialized dilator muscles of the salivary duct. The reconstruction of the relationships of the pistilliferan taxa is strongly impeded by a serious lack of morphological data. However, a group comprising Eomeropidae, Choristidae, Apteropanorpidae, Panorpidae and Panorpodidae is supported in our analyses. Further well documented anatomical data are needed for a reliable reconstruction of mecopteran relationships. The collecting and morphological study of larvae should also have high priority. Inherent problems are extreme secondary modifications of cephalic features of Caurinus and Nannochorista.     

Goodbye Halteria? The thoracic morphology of Endopterygota (Insecta) and its phylogenetic implications

Characters of the thorax of 30 representatives of all endopterygote orders and four hemimetabolous outgroup taxa were examined. In total, 126 characters potentially useful for phylogenetic reconstruction are discussed and presented as a data matrix. The thoracic features were analysed with different approaches combined with an additional large set of morphological data. Endopterygota were confirmed as monophyletic and new morphological autapomorphies of the group are suggested. The highly controversial Strepsiptera are not placed as sistergroup of Diptera (Halteria‐concept) but consistently as sistergroup of Coleoptera. This clade was mainly supported by characters associated with posteromotorism. The traditionally proposed relationship of Neuropterida + Coleoptera was not confirmed. Hymenoptera was placed as sistergroup of all remaining orders in parsimony analyses. The inclusion of Strepsiptera + Coleoptera in Mecopterida in parsimony analyses is probably artificial and potential thoracic autapomorphies of Mecopterida in the traditional sense are suggested. Mecopterida are confirmed as a clade in Bayesian analyses. Amphiesmenoptera and Antliophora are well supported. The paraphyly of Mecoptera is due to a clade comprising Nannochoristidae and Siphonaptera + Diptera. The phylogenetic reconstruction using characters of the thorax is impeded by functional constraints, parallel losses, a general trend to reinforce the skeleton and to simplify the muscular apparatus, and also by different specializations occurring in potential outgroup taxa. The addition of a large additional morphological data set only partly compensated for these problems. It is apparent that the inclusion of more outgroup and ingroup taxa is required, notably presumably basal representatives of Mecoptera, Trichoptera, and Diptera. This may reduce the effect of an artificial attraction of branches caused by homoplasy, notably character losses occurring within different lineages.© The Willi Hennig Society 2010.     

A longstanding entomological problem finally solved? Head morphology of Nannochorista (Mecoptera,Insecta) and possible phylogenetic implications

External and internal head structures of Nannochorista species were examined and described in detail. The characters are discussed with regard to their functional and phylogenetic implications. The structure of the mouthparts indicates that adults of Nannochorista feed on fluids. The loss of the mandibular muscles and the precerebral pharyngeal dilators are presumptive autapomorphies of the genus. A possible clade comprising Nannomecoptera, Siphonaptera and Diptera is supported by the presence of a labral food channel, the absence of the galea, a sheath for the paired mouthparts formed by the labium, very strongly developed labial palp muscles and cibarial dilators, and the presence of a well‐defined postcerebral pharyngeal pumping chamber. Closer affinities of Nannomecoptera with Diptera are suggested by the presence of a unique sensorial groove on the third maxillary palpomere. Further potential synapomorphies are the presence of a frontal apodeme and a primarily lamelliform mandible without teeth. The presence of a salivary channel on the laciniae and a subdivided labrum are shared derived features of Nannochorista and Siphonaptera. A derived condition present in Mecoptera including Boreidae but excluding Nannochoristidae is the secretion with a strongly developed intrinsic muscle of the salivary duct. The loss of the lateral labral retractor, the cranial muscle of the cardo, and of two of the three premental retractors, and the absence of transverse epipharyngeal muscles are potential autapomorphies of Antliophora. The formation of a maxillolabial complex is a possible synapomorphy of Hymenoptera and Mecopterida.     

Head morphology of Caurinus (Boreidae, Mecoptera) and its phylogenetic implications

External and internal head structures of Caurinus dectes were examined and described in detail. The features are compared to conditions found in other groups of Antliophora. Caurinus is obviously crucial for the reconstruction of the mecopteran and antliophoran groundplan. It displays a remarkable series of plesiomorphic character states such as a complete clypeolabral suture, the presence of M. hypopharyngomandibularis (M. 13) and M. frontohypopharyngalis (M. 41), a subdivided clypeus, a short head without rostrum, a dorsal tentorial arm attached to the head capsule, the absence of a cranial dilator of the antenna, and large mandibles with a well developed apical tooth, two distinct subapical teeth, and a basal molar part. The first three plesiomorphic features render potential autapomorphies of Mecoptera in the traditional sense invalid. Autapomorphies of Caurinus are the distinctly flattened labrum, the absence of the labroepipharyngeal muscle, the very large size of M. 13, the strongly enlarged penultimate palpomeres, the partition of M. 41, the very strongly developed precerebral sucking chamber, strongly curved optic lobes, the presence of a large protocerebral extension in the genal region and deep posterior excavations of the protocerebrum. The maxillolabial plate, the absence of cardines as separate structures, the reduction of ocelli, and the origin of maxillary palp muscles on a median ridge or area of the maxillolabial plate are likely autapomorphies of Boreidae. Another potential autapomorphy of the family is the presence of longitudinal furrows on the mandibles. However, they are absent in Boreus. The thick strongly sclerotised, median ridge of the maxillolabial plate, the missing retractibility of the prementum, the absence of extrinsic labial muscles, and the presence of a median ridge on the prepharyngeal roof suggest a clade Boreus + Hesperoboreus. The origin of extrinsic maxillary muscles from the clypeus has probably evolved independently in Boreus and Hesperoboreus, and in Panorpa, respectively. The absence of M. craniolacinialis and the presence of a row of several subapical mandibular teeth are autapomorphies of Boreus. The presence of a specific intrinsic muscle of the salivary duct and a membranous galea enclosing the labrum and mandibular base are derived features shared by Boreidae and Pistillifera (galea absent in Nannochorista, Siphonaptera and Diptera). The loss of M. frontolabralis (M. 8) is a potential apomorphy of Mecoptera incl. Siphonaptera. A sister group relationship between Boreidae and Siphonaptera is not supported by characters of the adult head. Head structures of Siphonaptera are extremely modified in correlation with ectoparasitic habits.     

The phylogenetic system of the Mecoptera

Abstract. Many families like the Mesochoristidae, Agetopanorpidae and Permopanorpidae, which were believed by earlier writers to be Mecoptera, are members of the stem group of the Antliophora (Diptera Mecoptera+Siphonaptera) or of stem groups of monophyletic groups of even higher rank (e.g. Mecopteroidea). Others - like the so-called 'Pro-tomecoptera' from the Permian of the Kusnetsk Basin - are not even closely related to the Mecopteroidea. Only the families mentioned in the following phylogenetic system of the Mecoptera are definitely members of the order:
1 Nannomecoptera (Nannochoristidae)
2 Pistillifera
2.1 Raptipedia (Neorthophlebiidae, Bittacidae, Cimbrophlebiidae)
2.2 Opisthogonopora
2.2.1 Boreomorpha (Boreidae)
2.2.2 Meropomorpha (Meropeidae)
2.2.3 Panorpomorpha
2.2.3.1 Eomeropina (Eomeropidae=Notiothaumidae)
2.2.3.2 Panorpina
2.2.3.2.1 Apteropanorpini (Apteropanorpidae)
2.2.3.2.2 Panorpini
2.2.3.2.2.1 Choristoidea (Choristidae)
2.2.3.2.2.2 Panorpoidea (Orthophlebiidae, Dinopanorpidae, Austropan-orpidae, Muchoriidae, Panorpodidae, Panorpidae)
The Orthophlebiidae and Neorthophlebiidae are not monophyletic. There are, however, no characters preserved which would allow a clarification of the exact relations between members of these two groups and the families derived from them. The fossil Xenochoristidae, Triasso-choristidae, Mesopanorpodidae and Robinjohniidae may be further members of the Mecoptera. Their exact phylogenetic relations, however, are unknown.     

The Strepsiptera problem: phylogeny of the holometabolous insect orders inferred from 18S and 28S ribosomal DNA sequences and morphology

Phylogenetic relationships among the holometabolous insect orders were inferred from cladistic analysis of nucleotide sequences of 18S ribosomal DNA (rDNA) (85 exemplars) and 28S rDNA (52 exemplars) and morphological characters. Exemplar outgroup taxa were Collembola (1 sequence), Archaeognatha (1), Ephemerida (1), Odonata (2), Plecoptera (2), Blattodea (1), Mantodea (1), Dermaptera (1), Orthoptera (1), Phasmatodea (1), Embioptera (1), Psocoptera (1), Phthiraptera (1), Hemiptera (4), and Thysanoptera (1). Exemplar ingroup taxa were Coleoptera: Archostemata (1), Adephaga (2), and Polyphaga (7); Megaloptera (1); Raphidioptera (1); Neuroptera (sensu stricto = Planipennia): Mantispoidea (2), Hemerobioidea (2), and Myrmeleontoidea (2); Hymenoptera: Symphyta (4) and Apocrita (19); Trichoptera: Hydropsychoidea (1) and Limnephiloidea (2); Lepidoptera: Ditrysia (3); Siphonaptera: Pulicoidea (1) and Ceratophylloidea (2); Mecoptera: Meropeidae (1), Boreidae (1), Panorpidae (1), and Bittacidae (2); Diptera: Nematocera (1), Brachycera (2), and Cyclorrhapha (1); and Strepsiptera: Corioxenidae (1), Myrmecolacidae (1), Elenchidae (1), and Stylopidae (3). We analyzed approximately 1 kilobase of 18S rDNA, starting 398 nucleotides downstream of the 5' end, and approximately 400 bp of 28S rDNA in expansion segment D3. Multiple alignment of the 18S and 28S sequences resulted in 1,116 nucleotide positions with 24 insert regions and 398 positions with 14 insert regions, respectively. All Strepsiptera and Neuroptera have large insert regions in 18S and 28S. The secondary structure of 18S insert 23 is composed of long stems that are GC rich in the basal Strepsiptera and AT rich in the more derived Strepsiptera. A matrix of 176 morphological characters was analyzed for holometabolous orders. Incongruence length difference tests indicate that the 28S + morphological data sets are incongruent but that 28S + 18S, 18S + morphology, and 28S + 18S + morphology fail to reject the hypothesis of congruence. Phylogenetic trees were generated by parsimony analysis, and clade robustness was evaluated by branch length, Bremer support, percentage of extra steps required to force paraphyly, and sensitivity analysis using the following parameters: gap weights, morphological character weights, methods of data set combination, removal of key taxa, and alignment region. The following are monophyletic under most or all combinations of parameter values: Holometabola, Polyphaga, Megaloptera + Raphidioptera, Neuroptera, Hymenoptera, Trichoptera, Lepidoptera, Amphiesmenoptera (Trichoptera + Lepidoptera), Siphonaptera, Siphonaptera + Mecoptera, Strepsiptera, Diptera, and Strepsiptera + Diptera (Halteria). Antliophora (Mecoptera + Diptera + Siphonaptera + Strepsiptera), Mecopterida (Antliophora + Amphiesmenoptera), and Hymenoptera + Mecopterida are supported in the majority of total evidence analyses. Mecoptera may be paraphyletic because Boreus is often placed as sister group to the fleas; hence, Siphonaptera may be subordinate within Mecoptera. The 18S sequences for Priacma (Coleoptera: Archostemata), Colpocaccus (Coleoptera: Adephaga), Agulla (Raphidioptera), and Corydalus (Megaloptera) are nearly identical, and Neuropterida are monophyletic only when those two beetle sequences are removed from the analysis. Coleoptera are therefore paraphyletic under almost all combinations of parameter values. Halteria and Amphiesmenoptera have high Bremer support values and long branch lengths. The data do not support placement of Strepsiptera outside of Holometabola nor as sister group to Coleoptera. We reject the notion that the monophyly of Halteria is due to long branch attraction because Strepsiptera and Diptera do not have the longest branches and there is phylogenetic congruence between molecules, across the entire parameter space, and between morphological and molecular data.     

The larval abdomen of the enigmatic Nannochoristidae (Mecoptera,Insecta)

External and internal structures of the larval abdomen of Nannochorista are described in detail, with emphasis on the posterior segments. The results are compared with conditions found in other groups of Antliophora, especially the mecopteran subgroups Boreidae and Pistillifera. Like the entire postcephalic body, the larval abdomen of Nannochorista is extremely slender and nearly cylindrical. The anterior segments are largely unmodified. The surface is smooth and lacks any protuberances or prolegs. The term “cloaca” for the posterior membranous pouch of Nannochorista sp. is morphologically unjustified. A list of muscles of segments IX and X is presented. The abdominal musculature was partly homologized following Snodgrass. The muscles of segment X are highly modified. They move the membranous pouch, the anal papillae, and the terminal lobes. The presence of these structures is likely an adaptation to the specific aquatic life style of nannochoristid larvae. The anal papillae are possibly homologous to the 4-lobed terminal attachment apparatus of larvae of Caurinus (Boreidae) and Pistillifera (Panorpidae, Bittacidae, Choristidae) but this is uncertain. The specific condition in both groups, i.e. two retractile papillae with tracheae and Malpighian tubules in Nannochoristidae, and a 4-lobed exposed attachment device in Pistillifera + Boreidae (groundplan) are very likely autapomorphic for both groups, respectively. A slender abdomen with smooth surface is very likely plesiomorphic within Antliophora and Mecopterida. This condition is found in Trichoptera (partim), Nannochoristidae, Siphonaptera, and many basal groups of Diptera. An eruciform or scarabaeiform body shape with a soft, largely unsclerotised cuticle is probably a synapomorphy of Boreidae and Pistillifera. The presence of ventral protuberances resembling prolegs on the anterior segments is an autapomorphy of the latter group. The homology of paired or unpaired terminal appendages of segment X is uncertain. However, the specific condition of paired and 3-segmented appendages with hooks in Nannochoristidae is almost certainly autapomorphic for this family. The protracted opening of the hind gut on the membranous pouch is another potential autapomorphy of Nannochoristidae. Aquatic habits of larvae, also very likely an apomorphic condition, have likely evolved several times independently in Antliophora.     

Endopterygote systematics – where do we stand and what is the goal (Hexapoda,Arthropoda)?

Abstract. Impressive progress has been made recently in the systematics of holometabolous insects. Nevertheless, important questions remain controversial, and uncertainties concerning the relationships of major lineages may even have increased. New analytical techniques have been developed and an immense wealth of molecular data has accumulated. Although no decisive breakthrough has yet been achieved, recent analyses of large molecular datasets have contributed greatly to the reconstruction of the phylogeny of several holometabolous lineages. Extensive combined analyses with substantial morphological datasets and molecular data comprising several genes (‘total evidence’) are still required for a well‐founded phylogenetic hypothesis for the entire group. Endopterygota monophyly is supported mainly by the specific and derived mode of development, which may be considered as a new evolutionary level within Hexapoda. The basal branching pattern remains controversial. A division into two large clades comprising Coleoptera (+ Strepsiptera?) + Neuropterida, on the one hand, and Hymenoptera + [Amphiesmenoptera + Antliophora (including Strepsiptera?)], on the other, appears plausible. Alternative hypotheses have been proposed based on wing characters and molecular data. The position of Strepsiptera remains unsolved. Mecoptera almost certainly is not monophyletic, as Siphonaptera are probably sister to Boreidae. Immense progress has been made in the reconstruction of the intraordinal relationships of all orders, thanks to increasing studies based on combined datasets. Common efforts of morphologists and molecular systematists probably will lead to further rapid progress. Several discoveries of new higher ranking taxa during recent years have revealed that large‐scale habitat destruction will not only have disastrous effects on global biodiversity, but also on the study of insect phylogeny and evolution.     

The morphology and evolution of the female postabdomen of Holometabola (Insecta)

In the present article homology issues, character evolution and phylogenetic implications related to the female postabdomen of the holometabolan insects are discussed, based on an earlier analysis of a comprehensive morphological data set. Hymenoptera, the sistergroup of the remaining Holometabola, are the only group where the females have retained a fully developed primary ovipositor of the lepismatid type. There are no characters of the female abdomen supporting a clade Coleopterida + Neuropterida. The invagination of the terminal segments is an autapomorphy of Coleoptera. The ovipositor is substantially modified in Raphidioptera and distinctly reduced in Megaloptera and Neuroptera. The entire female abdomen is extremely simplified in Strepsiptera. The postabdomen is tapering posteriorly in Mecopterida and retractile in a telescopic manner (oviscapt). The paired ventral sclerites of segments VIII and IX are preserved, but valvifers and valvulae are not distinguishable. In Amphiesmenoptera sclerotizations derived from the ventral appendages VIII are fused ventromedially, forming a solid plate, and the appendages IX are reduced. The terminal segments are fused and form a terminal unit which bears the genital opening subapically. The presence of two pairs of apophyses and the related protraction of the terminal unit by muscle force are additional autapomorphies, as is the fusion of the rectum with the posterior part of the genital chamber (cloaca). Antliophora are supported by the presence of a transverse muscle between the ventral sclerites of segment VIII. Secondary egg laying tubes have evolved independently within Boreidae (absent in Caurinus) and in Tipulomorpha. The loss of two muscle associated with the genital chamber are likely autapomorphies of Diptera. The secondary loss of the telescopic retractability of the postabdomen is one of many autapomorphies of Siphonaptera.     

The female postabdomen of the enigmatic Nannochoristidae (Insecta: Mecopterida) and its phylogenetic significance

Hünefeld, F. and Beutel, R.G. 2011. The female postabdomen of the enigmatic Nannochoristidae (Insecta: Mecopterida) and its phylogenetic significance. —Acta Zoologica (Stockholm) 00: 1–8. External and internal features of the female postabdomen of Nannochorista neotropica are described in detail. The conditions found in females of Nannochoristidae come closest to the ground plan of Mecopterida. This lineage is characterised by telescoping postabdominal segments, a presumptive autapomorphic feature that is modified in some antliophoran groups, but displayed by the nannochoristid species in a typical manner. More potential autapomorphies of Mecopterida, all present in Nannochoristidae, are the neo‐formation of an intersegmental muscle, a transverse muscle spanning between the genital appendages of segment VIII, a muscle connecting these appendages and the genital chamber and the loss of an intersegmental muscle. Plesiomorphic features of Nannochoristidae are the presence of paired genital appendages on segments VIII and IX. Information on the egg‐depositing substrates of the females is not available. The telescoping postabdomen is suitable for oviposition in soft substrates such as moist soil, or rotten plant materials in the riparian zone, and this is possibly a ground‐plan feature of Mecopterida. The results of recent phylogenetic analyses based on morphological data support a placement of Nannochoristidae in Antliophora, whereas the exact position of the group remains ambiguous. No characters of the female postabdomen were found supporting the monophyly of Mecoptera as conventionally circumscribed, that is Nannochoristidae + Boreidae + Pistillifera.     

Resolving insect phylogeny: The significance of cephalic structures of the Nannomecoptera in understanding endopterygote relationships

The Nannomecoptera are among the most enigmatic and controversial taxa of endopterygote insects, the phylogenetic resolution of which is crucial to understanding the evolution of neopteran insects. Once considered a subordinate lineage within the Mecoptera, renewed interest in nannochoristids has been prompted by evidence that the Nannomecoptera are not admissible to the clade of extant scorpion flies but are more likely to belong to the clade Siphonaptera + Nannomecoptera + Diptera. The overarching purpose of the present account is to provide novel and extensive morphological character traits in addition to those already existing for adult structures. The aim is to determine if these traits support molecular data sets that have been suggested elsewhere to clarify the phyletic position of Nannochoristidae. This account focuses on nannomecopteran larvae, which unlike those of other mecopterans have received little attention. Thus, the thrust of this investigation is to provide detailed anatomical data on nannochoristid larvae for a targeted inquiry into their phylogenetic affinities. The described characters are discussed and presented in a data matrix comprising representatives of all endopterygote orders. While the study is based primarily on the New Zealand species Nannochorista philpotti, it is proposed that all nannomecopteran larvae will prove to be similar to this taxon in most if not all structural features of significance to a higher-level phylogenetic context.     

Phylogeny of the holometabolous insect orders: molecular evidence

Phylogenetic relationships among the holometabolous insect orders were reconstructed using 18S ribosomal DNA data drawn from a sample of 182 taxa representing all holometabolous insect orders and multiple outgroups. Parsimony analysis supports the monophyly of all holometabolous insect orders except for Coleoptera and Mecoptera. Mecoptera is paraphyletic with respect to Siphonaptera, which is nested within Mecoptera. Coleoptera is scattered as a paraphyletic assemblage across the tree topology. These data support a monophyletic Halteria (Strepsiptera + Diptera), Amphiesmenoptera (Trichoptera + Lepidoptera), Neuropterida (Neuroptera + (Megaloptera + Raphidioptera)), but Antliophora (Halteria + Mecoptera + Siphonaptera) and Mecopterida (Antliophora + Amphiesmenoptera) are paraphyletic. The limitations of using 18S ribosomal DNA as the sole phylogenetic marker for reconstructing insect ordinal relationships are discussed.     

Characterization of the long-wavelength opsin from Mecoptera and Siphonaptera: does a flea see?

Mecoptera and Siphonaptera represent two insect orders that have largely been overlooked in the study of insect vision. Recent phylogenetic evidence demonstrates that Mecoptera (scorpionflies) is paraphyletic, with the order Siphonaptera (fleas) nesting as sister to the family Boreidae (snow fleas), showing an evolutionary trend towards reduction in gross eye morphology within fleas. We provide the first molecular characterization of long-wavelength opsins from these three lineages (opsin gene from fleas [FL-Opsin], the Boreidae [B-Opsin], and a mecopteran family [M-Opsin]) and assess the effects of loss of visual acuity on the structure and function of the opsin gene. Phylogenetic analysis implies a physiological sensitivity in the red-green spectrum for these opsins. Analysis of intron splice sites reveals a high degree of similarity between FL-Opsin and B-Opsin as well as conserved splice sites across insect blue-green and long-wavelength opsins. Calculated rates of evolution and tests for destabilizing selection indicate that FL-Opsin, B-Opsin, and M-Opsin are evolving at similar rates with no radical selective pressures, implying conservative evolution and functional constraint across all three lineages.     

Mecoptera is paraphyletic: multiple genes and phylogeny of Mecoptera and Siphonaptera

Phylogenetic relationships among members of the Mecoptera and Siphonaptera were inferred from DNA sequence data. Four loci (18S and 28S ribosomal DNA, cytochrome oxidase II and elongation factor-1α) were sequenced for 69 taxa selected to represent major flea and mecopteran lineages. Phylogenetic analyses of these data support a paraphyletic Mecoptera with two major lineages: Nannochoristidae + (Siphonaptera + Boreidae) and Meropidae + ((Choristidae + Apteropanorpidae) (Panorpidae + (Panorpidae + Bittacidae))). The flea family Ctenophthalmidae is paraphyletic, and the Ceratophylloidea is monophyletic. Morphological evidence is discussed which is congruent with the placement of Siphonaptera as sister group to Boreidae.     

Classification of flea families (Siphonaptera): I. Family Hystrichopsyllidae (first part)

A contribution is made to the previously elaborated classification of the order Siphonaptera (Medvedev, 1994, 1998). Host-parasite associations, geographical distribution, and morphology of the family Hystrichopsyllidae (sensu Hopkins and Rothschild, 1962, 1966) in comparison with other flea families are analyzed together with a position of the family within the infraorder Hystrichopsyllomorpha. The presence of two spermathecae, frequently used as a taxonomic character, is a character insufficient for the basic phylogenetic reconstructions, e.g., establishment of close relationship between the families Coptopsyllidae and Macropsyllidae or the tribes Ctenopariini and Hystrichopsyllini, because this character is a plesiomorphy of the order Siphonaptera. The subfamily Hystrichopsyllinae (sensu Hopkins and Rothschild, 1962) is characterized by a large number of morphological features which can be considered as plesiomorphic characters of the family Hystrichopsyllidae as a whole. The subfamily Hystrichopsyllinae should be restricted to the tribes Ctenopariini and Hystrichopsyllini. The family Macropsyllidae possesses a unique structure of the ctenidia and some other structures. It should be treated as a group closely related to Hystrichopsyllidae. The family Coptopsyllidae demonstrates another trend in the evolution of the head, thorax, and abdomen.     

On the thoracic anatomy of the Madagascan Heterogyrus milloti and the phylogeny of Gyrinidae (Coleoptera)

Gyrinidae is a group of beetles with a unique specialization of swimming on the water surface. Heterogyrus milloti Legros (Heterogyrinae) from Madagascar is a species with various preserved plesiomorphic features. The information on the morphology and biology was very limited until recently, and the thoracic anatomy remained largely unknown. Consequently, the aim of the present study is to describe external and internal thoracic features of Heterogyrus Legros in detail and to interprete them with respect to their phylogenetic and functional significance, with a special focus on the unusual flight apparatus of Gyrinidae. Characters documented with innovative techniques are compared to conditions found in other gyrinid genera and other groups of Adephaga, including characters of other body parts and larvae. A data matrix with 144 characters of adults, larvae and eggs was compiled and analysed cladistically. Gyrinidae excluding Spanglerogyrus Folkers (Heterogyrinae + Gyrininae) is supported by many apomorphies, mainly by a unique locomotor apparatus with paddle‐like middle and hind legs. The results confirm Heterogyrus as the earliest diverging branch in Gyrinidae except Spanglerogyrus, implying a sister‐group relationship between this genus and Gyrininae, a clade comprising Gyrinini, Dineutini and Orectochilini. The presence of an opening between the mesanepisternum and elytra, reduction of the lateral metafurcal arms, loss of the metathoracic M. furcacoxalis lateralis, and modifications of the head, including the dorsal shift of the upper subcomponent of the compound eyes, are synapomorphies of the three tribes. The monophyly of Gyrinini is moderately well‐supported, whereas Orectochilini is strongly supported by different characters including a highly simplified but functioning flight apparatus. A clade comprising Orectochilini and the dineutine genera is suggested by synapomorphies of adults and larvae. The monophyly of Dineutini was supported in a recent study, but not by the characters analysed here. Features of adults, larvae and eggs indicate that Gyrinidae are the sister group to the remaining adephagan families, as suggested in some earlier morphology‐based studies and recent analyses of large molecular datasets.     

First μ‐CT‐based 3D reconstruction of a dipteran larva—the head morphology of protanyderus (tanyderidae) and its phylogenetic implications

The larval head of Protanyderus was examined and documented using innovative techniques, with emphasis on internal structures. A chart listing all head muscles of dipteran larvae and other holometabolan groups is presented in the Supporting Information. The results are compared to conditions found in other nematoceran lineages. The larval head of Protanyderus is characterized mainly by plesiomorphic character states such as the complete and largely exposed head capsule, the long coronal suture, V‐shaped frontal sutures, lateral antennal insertion areas, a transverse labrum, a nearly horizontal plane of mandibular movements, mandibles lacking a movable distal part, a mesal hook and mesal or distal combs, separated maxillary endite lobes, a comparatively complete array of muscles, and a brain only partly located within the head capsule. An anteriorly toothed hypostomal plate and dense labral brushes of microtrichiae are also likely groundplan features of Diptera. The pharyngeal filter is a possible apomorphy of Diptera excl. Deuterophlebiidae (or Deuterophlebiidae + Nymphomyiidae). The messors have also likely evolved early in the dipteran crown group but are absent in the groundplan. The phylogenetic interpretation of externolateral plates with growth lines is ambiguous. Autapomorphies of Tanyderidae are differences between the third and fourth instar larvae, the roof‐like extension above the antennal insertion area, the dorsal endocarina, and the posterodorsal internal ridge. The phylogenetic position of Tanyderidae is controversial, but features of the larval head do not support a proposed sistergroup relationship between Tanyderidae and Psychodidae. Both groups differ in many features of the larval head, and we did not identify a single potential synapomorphy. Larval characters alone are insufficient for a reliable phylogenetic reconstruction, though they vary greatly and apparently contain phylogenetic information. The evaluation of these features in the context of robust molecular phylogenies will be a sound basis for the reconstruction of complex evolutionary scenarios for the megadiverse Diptera. Diptera. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc.     

Stigma structure and variation in Bromeliaceae—Neglected taxonomic characters

Three distinct types of stigma architecture, designated as “simple-erect,” “conduplicate-spiral”, and “convolute-blade” were identified for Bromeliaceae. Structure of the conduplicate-spiral and convolute-blade stigma types is highly complex and previously unreported. Stigma morphology, largely neglected in Tillandsioideae until recently, promises to yield new characters valuable in interpreting systematic relationships in this subfamily. Data indicate that the putatively plesiomorphic state (simple-erect) is retained in some members of all three subfamilies. We found convolute-blade-type stigmas only in Tillandsioideae, though not in all members of the subfamily. Our sample indicates that Tillandsioideae stigmas are more like those of Pitcairnioideae than of Bromelioideae, which is consistent with Smith’s hypothesis of phylogenetic proximity of Tillandsioideae and Pitcairnioideae. Stigma architecture is proving to be a rich source of data for phylogenetic reconstruction and for classification at several infrafamilial levels.     

Structure of the ovary in Nannochorista neotropica Navás (Insecta: Mecoptera: Nannochoristidae) with remarks on mecopteran phylogeny

Preliminary histological analysis showed that the ovaries in Nannochorista neotropica are composed of numerous ovarioles of panoistic type. In the ovaries of adult females each ovariole consists of a terminal filament, vitellarium and pedicle while a germarium is absent. Morphological observations supported by simple histochemical tests revealed the presence of multiple nucleoli in the oocyte nucleus. The appearance of multiple nucleoli suggests that the extrachromosomal amplification of ribosomal DNA may take place in the oocytes of Nannochorista. The results show that in the structure of the ovariole and the course of oogenesis nannochoristids share noteworthy derived features with boreids, but differ significantly from all other mecopterans. These findings indicate the possible monophyly of an assemblage comprising the Nannomecoptera, Neomecoptera and Siphonaptera.