Cephalic anatomy of Sphaeriusidae and a morphology‐based phylogeny of the suborder Myxophaga (Coleoptera)

Myxophaga are a small group of beetles, but phylogenetically crucial as one of the four coleopteran suborders. The monogeneric Sphaeriusidae, one of four myxophagan families, comprise about 20 species, most of them living in moist substrate at river edges. The morphology of the minute hemispherical adult is very insufficiently known. Consequently, we document external and internal head structures using scanning electron microscopy, microtome sections and three‐dimensional reconstructions. The results are discussed with respect to effects of miniaturization and also functional aspects, especially microphagous feeding habits. The head of Sphaerius is less affected by size reduction compared with other beetles of the same size class (e.g. larger Ptiliidae, Corylophidae). Features related to very small size are the absence of externally visible ridges and a partial shift of the brain into the prothorax. The cephalic musculature is apparently not affected. The feeding apparatus is similar to what is found in microphagous species of Polyphaga, especially in Scirtoidea and Staphyliniformia. However, in contrast to polyphagans with similar feeding habits, the hypopharyngeal longitudinal ridge (or process) of Sphaerius is strongly reduced and a fimbriate galea is lacking. The observed features are also evaluated in a cladistic analysis of larval and adult characters. The results are distinctly in conflict with branching patterns suggested by analyses of molecular data, but in agreement with previous morphological studies. In contrast to a pattern obtained in a recent molecular study – (Hydroscaphidae + (Torridincolidae + (Sphaeriusidae + Lepiceridae))) – our analyses yielded Lepiceridae as sister to the remaining Myxophaga (branch support 9), and Sphaerius as sister taxon of Hydroscaphidae (branch support 5). The monophyletic origin of the latter two taxa is supported by unusual synapomorphies of adults and larvae. Sphaerius is characterized by numerous autapomorphies of the head: a labro‐mandibular locking device, a bipartite M. frontoepipharyngalis (M9) with subcomponents oriented in the opposite direction, a deep antennal furrow, an intercalary antennomere with a structure resembling a sucking disc, a strongly elongated flagellomere 1, a compact three‐segmented antennal club, strong bundles of M. tentorioscapalis (M4) originating on the posterior head capsule, a concave anterior side of maxillary palpomere 2, and an elongated second pair of tormae posteriorly connected with a process of the hypopharyngeal suspensorium.     

Phylogenetic analysis of Myxophaga (Coleoptera) using larval characters

A phylogenetic parsimony analysis of fifty-four larval characters of Myxophaga (excluding Lepiceridae) resulted in two minimal length cladograms. The monophyly of Torridincolidae, Hydroscaphidae and Microsporidae is supported by several autapomorphies: miniaturization, flattened body with laterally extended tergites, broadened head, scale-like surface structures, broad tentorial bridge, disc-shaped labral sensilla, spiracular gills and pupation in the last larval exuviae. Hydroscaphidae are the sister group of Microsporidae. Larvae of both families are characterized by semi-entognathous mouthparts, tergites with posterior rows of lancet-shaped setae, claws with flattened basal spines and balloon-shaped spiracular gills. The monophyly of all families is supported by autapomorphies. Torridincolidae excluding Delevea is defined as a monophylum by four derived character states: body ovoid, thorax semicircular and as long as abdomen, labral sensilla fused and abdominal sternite IX distinctly reduced and triangular. The monophyly of Torridincolinae (sensu Endrödy-Younga 1997b) is supported by two autapomorphies. The proposed branching pattern suggests that the early representatives of Myxophaga (excluding Lepiceridae) were living in aquatic conditions with a preference for hygropetric habitats. The tendency to live on rocks in running water and miniaturization have played an important role in myxophagan evolution.     

Larval head morphology of Hydroscapha natans (Coleoptera, Myxophaga) with reference to miniaturization and the systematic position of Hydroscaphidae

 The head of third instar larvae of Hydroscapha natans was reconstructed three dimensionally on a computer. This technique allowed a detailed examination and presentation of internal features of a representative of the ’suborder’ Myxophaga, which is characterized by the very small size of the immature stages and adults. Larval character states of H. natans were compared with features found in other representatives of the Coleoptera. The monophyly of the Myxophaga (excluding Lepiceridae) is supported by several autapomorphies of the larval head: a broadened, transverse head, scale-like cuticular surface structures, round and flattened labral sensilla, short antennae with only two antennomeres, a ligula with papillae, and a broadened tentorial bridge. A monophylum comprising the Hydroscaphidae and Microsporidae is characterized by a very unusual semientognathous condition of the mouthparts and an unusual shape and large relative size of the brain. The last common ancestor of the Hydroscaphidae, Torridincolidae, and Microsporidae was probably living in hygropetric habitats. Several apomorphies have evolved in correlation with this peculiar life style. The very dense arrangement of muscles and other internal structures, and the unusual shape and size of the cerebrum have resulted from miniaturization. The overall complexity of the head is not reduced in comparison to larvae of other representatives of Coleoptera. A negative allometric relationship between body size and the size of the brain, and a correlation between brain size and the size of neurons was found in several species of Coleoptera examined. Accepted: 16 December 1997     

The morphology of the larval head of Tipulidae (Diptera, Insecta) - The dipteran groundplan and evolutionary trends

External and internal head structures of the larva of Tipula montium are described in detail. The results are compared to conditions found in other representatives of Tipuloidea and other dipteran and antliophoran lineages. Despite of the conceivably basal position of Tipulomorpha within Diptera, the larvae are mainly characterised by derived features. The partially retracted head, the specific hemicephalic condition and several other derived character states support the monophyly of Tipuloidea. A clade comprising Tipuloidea excluding Pediciidae is suggested by the strongly retracted head, by deep dorsolateral incisions of the head capsule, by a distinctly toothed anterior premental margin, by the loss of the second extrinsic maxillary muscle, and possibly by the loss of the pharyngeal filter. Eriopterinae and Hexatominae are characterised by a tendency towards an extreme reduction of the head capsule. Limoniinae, Cylindrotomidae, and Tipulidae form a clade supported by the presence of a premaxillary suture. This implies the non-monophyly of Limoniidae. A feature shared by Cylindrotomidae and Tipulidae is the presence of a movable lacinia mobilis. However, this is arguably a plesiomorphic feature, as it also occurs in Nannochoristidae. Features of the larval head of Trichoceridae, which were included in Tipulomorpha, do not show affinities with those of Tipuloidea. Trichocerid larvae share a specialised subdivided mandible with larvae of psychodomorph groups. Tipuloidea are a highly specialised group. The characters examined did not reveal plesiomorphic features supporting a basal position, and features suggesting closer affinities with Brachycera are vague. The evolution of dipteran larval head structures was apparently strongly affected by the loss of legs and the tendency to live in cryptic habitats. Diptera are the group of Endopterygota with the highest number of apomorphic features of the larval head. The appendages are generally simplified and the muscular apparatus is strongly reduced. Specialised features evolving within dipteran lineages include specifically arranged brushes of hairs on the labrum and epipharynx, movable messores, subdivided mandibles, different mandibular brushes, and a far-reaching reduction of labial parts.     

On the evolution of adult head structures and the phylogeny of Hydraenidae (Coleoptera, Staphyliniformia)

External and internal head structures of adults of Orchymontiinae, Prosthetopinae, Hydraeninae and Ochthebiinae were studied and those of Ochthebius semisericeus and Limnebius truncatellus are described in detail. The results are evaluated with respect to their relevance for a reconstruction of hydraenid phylogeny and also compared with structural features found in adults of other staphyliniform families. The monophyly of Hydraenidae is supported by the presence of a plate‐like, trilobed premento‐hypopharyngeal extension, an unusual origin of m. tentoriohypopharyngalis, dorsal tentorial arms firmly fused with the head capsule, modified basal antennomeres, and palpigers connected by a transverse sclerotized bar. Orchymontiinae are monophyletic and the basal sister group of the remaining Hydraenidae. The presence of a ventral transverse genal bulge and of a pubescent antennal club with more than two antennomeres (reversal in some prosthetopines: e.g. Mesoceration abstrictum) are possible apomorphies of Hydraenidae excluding Orchymontiinae. Prosthetopinae are probably monophyletic and the sister group of Ochthebiinae + Hydraeninae. The latter clade is characterized by a distinct cupula formed by antennomere VI, a loose five‐segmented pubescent antennal club, and a modified antennal musculature. The presence of an unusual tentorio‐pharyngeal dilator is a shared derived feature of Ochthebiinae and the genus Davidraena. The monophyly of Ochthebiinae was confirmed and Ochtheosus is the sister group of the remaining ochthebiine genera, which are characterized by a perforated wall‐like structure formed by the posterior tentorial arms. The absence of this tentorial modification and the fimbriate galea are plesiomorphies retained in Ochtheosus. Calobius differs strongly from other subgenera of Ochthebius and a generic status may be appropriate. The monophyly of Hydraeninae is not supported. Hydraena was confirmed as a clade and Laeliaena and Limnebius are sister groups. The latter genus is characterized by several autapomorphies. The basal position of Orchymontiinae and Prosthetopinae suggests a Gondwanan origin of Hydraenidae and a primary preference for life in running water. Important evolutionary changes of head structures are complex transformations of the antennae and related structures. Yet, the use of the antennae as accessory breathing organs is not a groundplan feature of the family. The results of this study strengthen the case of staphylinoid affinities of Hydraenidae.     

Phylogenetic analyses and evolutionary timescale of Coleoptera based on mitochondrial sequence

Coleopteran phylogeny was analysed using mitochondrial genome (mitogenome) sequence. The optimal tree topology was given by the dataset consisted of all coding genes except for the exclusion of the 3rd codon sites (mtDNA12) using Bayesian Inference Method. This topology supports the monophyly of four suborders, and the sister group relationship between Adephaga and Myxophaga and between Polyphaga and Archostemata. In Polyphaga, Cucujiformia and Elateroidea formed independent node respectively, the remaining species grouped together except for Cyphon sp, among which, only Cucujiformia and Scarabaeiformia were supported as monophyletic group, respectively. Within Cucujiformia, the monophyly of Chrysomeloidea, Curculionoidea and Tenebrionoidea were supported respectively, among which Tenebrionoidea occupied the basal position of Cucujiformia. Cleroidea grouped together with Bothrideridae and Coccinellidae, and formed an independent node, which lead to the paraphyly of Cucujoidea. The monophyly of Elateriformia was not supported because of the division of Scirtoidea and Buprestoidea. Furthermore, using a Bayesian relaxed clock calibrated with fossil data, we estimated that most superfamilies within Polyphaga originated in the Jurassic period.     

Antennal heart morphology supports relationship of Zoraptera with polyneopteran insects

The antennal hearts of the zorapteran Zorotypus hubbardi and of two psocopteran species (Caecilius sp., Embidopsocus sp.) are described in detail and compared to those of other insects. In Zorotypus, the ampullae of this organ are located dorsally of the antennal base. They are attached to the frontal cuticle of the head capsule and laterally suspended by two delicate bands of connective tissue. The associated muscles comprise a well‐developed M. interampullaris and a M. ampulloaortica, which together act as dilators of the ampullae. The connected antennal vessel has a very thin wall and is uniform along its entire length. In the two studied psocopterans the ampullae are likewise connected to the head capsule and have two additional elastic bands. In Caecilius sp. the anterior band is muscular, while in Embidopsocus sp. it is the posterior one. The psocopteran antennal hearts have no additional musculature. Antennal hearts with a musculature configuration resembling that of Zoraptera are known only from Dictyoptera, Phasmatodea and some orthopterans. This condition thus might be a synapomorphy of a polyneopteran subgroup including Zoraptera.     

Expression of <Emphasis Type="Italic">defective proventriculus</Emphasis> during head capsule development is conserved in <Emphasis Type="Italic">Drosophila</Emphasis> and stalk-eyed flies (<Emphasis Type="Italic">Diopsidae</Emphasis>)

Hypercephaly, in the form of lateral extensions of the head capsule, is observed in several families of Diptera. A particularly exaggerated form is found in Diopsid stalk-eyed flies, in which both eyes and antennae are laterally displaced at the end of stalks. The processes of early development and specification of the head capsule in stalk-eyed flies are similar to those in Drosophila melanogaster. In Drosophila the homeobox gene ocelliless (oc) shows a mediolateral gradient of expression across the region of the eye-antennal imaginal disc that gives rise to the head capsule and specifies the development of different head structures. The genes and developmental mechanisms that subsequently define head shape in Drosophila and produce hypercephaly in stalk-eyed flies remain unclear. To address this, we performed an enhancer trap screen for Drosophila genes expressed in the same region as oc and identified the homeobox gene defective proventriculus (dve). In the eye-antennal imaginal disc, dve is coexpressed with oc in the region that gives rise to the head capsule and is active along the medial edge of the antennal disc and in the first antennal segment. Analyses of dve expression in mutant eye-antennal discs are consistent with it acting downstream of oc in the development of the head capsule. We confirm that orthologues of dve are present in a diverse panel of five stalk-eyed fly species and analyse patterns of dve sequence variation within the clade. Our results indicate that dve expression and sequence are both highly conserved in stalk-eyed flies.M. Carr and I. Hurley contributed equally to this work.     

Head structures of males of Strepsiptera (Hexapoda) with emphasis on basal splitting events within the order

Internal and external head structures of males of Strepsiptera were examined and the head of a species of Mengenilla is described in detail. The results suggest a reinterpretation of some structures. The head of basal extant strepsipterans is subprognathous, whereas it is strictly orthognathous in the groundplan of Strepsiptera s.l. The labrum and hypopharynx are not part of the mouthfield sclerite. The labial palps are absent in all strepsipterans. A very slightly modified mandibular articulation is preserved in Eoxenos, whereas it is distinctly reduced in other extant groups. A salivary duct, salivary glands, and a cephalic aorta are absent. The cladistic analysis of 44 characters of the head results in the following branching pattern: (Protoxenos + (Mengea + (Eoxenos + (Mengenilla [Austr.] + Mengenilla) + (Elenchus + Dundoxenos + Xenos + Stylops)))). Most apomorphies of males are associated with the necessity of finding females within a short time span and with a reduced necessity to consume food: large "raspberry" eyes, flabellate antennae with numerous dome-shaped chemoreceptors, Hofeneder's organ, an ovoid sensillum of the maxillary palp, and the simplified condition of the maxilla and the labium. Strepsiptera excl. Protoxenos are supported by the dorsomedian frontal impression, the dorsally shifted antennal insertions, a reduced number of antennal segments, absence of the galea, and probably by the presence of the mouthfield sclerite, which is a unique apomorphic feature. The balloon-gut combined with an unusual air-uptake apparatus is another possible autapomorphy of this clade. It is likely that the last common ancestor of Strepsiptera excl. Protoxenos did not process food. Strepsiptera s.str. are characterized by the strongly reduced condition of the labrum and the absence of the epistomal suture. Eoxenos is the sister group of the remaining Strepsiptera s.str. Synapomorphies of Mengenilla + Stylopidia are the advanced reduction of the mandibular articulation and the secondary absence of the ovoid sensillum. The monophyly of Mengenilla is confirmed, even though a small free labrum is present in Australian species. Derived features of Stylopidia are the absence of the coronal suture and the reduced condition of the frontal suture. Apomorphies that have evolved within Stylopidia are the membranization of parts of the head, the fusion of antennal segments, the increase or decrease of the number of flabellate flagellomeres, reductions and modifications of the mandibles, and modifications of the mouthfield sclerite. The monophyly of Stylopiformia is not unambiguously supported. A position of the mandibles posterior to the mouthfield sclerite (when adducted) is a possible synapomorphy shared by Xenos, Stylops, and other "higher Stylopidia." The blade-like distal part of the mandibles suggests a closer relationship of Elenchus with these taxa.     

Monophyly of terrestrial adephagan beetles as indicated by three nuclear genes (Coleoptera: Carabidae and Trachypachidae)

The beetle suborder Adephaga is traditionally divided into two sections on the basis of habitat, terrestrial Geadephaga and aquatic Hydradephaga. Monophyly of both groups is uncertain, and the relationship of the two groups has implications for inferring habitat transitions within Adephaga. Here we examine phylogenetic relationships of these groups using evidence provided by DNA sequences from all four suborders of beetles, including 60 species of Adephaga, 4 Archostemata, 3 Myxophaga, and 10 Polyphaga. We studied 18S ribosomal DNA and 28S ribosomal DNA, aligned with consideration of secondary structure, as well as the nuclear protein-coding gene wingless . Independent and combined Bayesian, likelihood, and parsimony analyses of all three genes supported placement of Trachypachidae in a monophyletic Geadephaga, although for analyses of 28S rDNA and some parsimony analyses only if Coleoptera is constrained to be monophyletic. Most analyses showed limited support for the monophyly of Hydradephaga. Outside of Adephaga, there is support from the ribosomal genes for a sister group relationship between Adephaga and Polyphaga. Within the small number of sampled Polyphaga, analyses of 18S rDNA, wingless , and the combined matrix supports monophyly of Polyphaga exclusive of Scirtoidea. Unconstrained analyses of the evolution of habitat suggest that Adephaga was ancestrally aquatic with one transition to terrestrial. However, in analyses constrained to disallow changes from aquatic to terrestrial habitat, the phylogenies imply two origins of aquatic habit within Adephaga.     

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.     

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.     

Phylogenetic analysis of the family Ariidae (Ostariophysi: Siluriformes), with a hypothesis on the monophyly and relationships of the genera

Ariid monophyly and intrafamilial relationships are investigated based on cladistic analysis of 230 morphological characters. Terminal taxa examined include whenever possible type‐species, or the most morphologically similar species to the type‐species of the nominal genera, and the largest possible number of species, including cleared and stained specimens, available in zoological collections. Previous hypotheses about monophyly of the Ariidae are strongly corroborated by new synapomorphies discovered in the present study. The subfamily Galeichthyinae and the remaining ariids are strongly supported by new morphological characters. The monotypic subfamily Bagreinae is recognized as the sister group to all nongaleichthyin ariids, supported by a large series of exclusive synapomorphies. A new concept of Ariinae is presented: the subfamily is found to be unequivocally monophyletic and includes all ariid genera, except Galeichthys and Bagre. New data supporting the monophyly of the genera included in the Ariinae are introduced and previous hypotheses of monophyly, species composition, morphological definition, and relationships are reviewed and discussed.     

Antennal motor system of the cockroach, <Emphasis Type="Italic">Periplaneta americana</Emphasis>

The organization of the antennal muscles, nerves, and motor neurons has been investigated in the cockroach, Periplaneta americana. Antennal movements have been observed by video analysis, muscle actions have been determined by dissection and direct mechanical testing, and the motor neurons innervating each muscle have been defined with a recently developed selective backfill method. A model of the antennomotor system of Periplaneta has thus been established and compared with that of crickets. Five muscles located within the head capsule insert on the most proximal antennal segment, the scape. By their action, they allow the scape to move in essentially any direction within the dorsoventral and anteroposterior planes. An additional pair of muscles, one dorsal and one ventral, are found within the scape. They insert on the pedicel and move the pedicel in the dorsal-ventral plane. These seven muscles are controlled by at least 17 motor neurons with somata located in the deutocerebrum. By their action, these motor neurons enable cockroaches to move the long flagellum of each antenna through a wide range of positions in the frontal space, medio-laterally, and also allow depression toward the substrate and elevation well above the level of the head. The antennal motor neurons have been classified into five morphological types based on soma and axon location. Each morphological type has been correlated with a particular pattern of muscle innervation and control. The neurites of all motor neurons are located along the medial aspect of the dorsal lobe of the deutocerebrum. This research was supported by grant nos. IBN 96-04629 and 04-22883 from the National Science Foundation.     

The larval head of Exechia (Mycetophilidae) and Bibio (Bibionidae) (Diptera)

Exechia and Bibio have retained several plesiomorphic groundplan features of Diptera and Bibionomorpha, including a fully exposed and sclerotized head capsule, the transverse undivided labrum, the absence of movable premandibles, and undivided mandibles without combs. The fusion of the hypostomal bridge with the head capsule and largely reduced antennae are derived features shared by both taxa. The absence of teeth at the anterior hypostomal margin is a potential autapomorphy of Bibionomorpha. A basal position of Anisopodidae is suggested by a number of plesiomorphies retained in this family. Apomorphies of Bibionomorpha excluding Anisopodidae are the reduction of tentorial elements, the partial fusion of the labrum and clypeus, one-segmented antennae, the absence of a separate submental sclerite, the loss of the labial palpus, and the reduction of the pharyngeal filter apparatus. Head structures of Bibio are largely unmodified. The subprognathous orientation is one of few autapomorphic features. In contrast, the mouthparts of Exechia are highly modified in correlation with the specialized food uptake. The rasping counterrotating movements of maxillae and mandibles with teeth oriented in opposite directions are carried out by strongly developed extensors and flexors of the paired mouthparts. The modified labium mechanically supports the “drill head” formed by the mandibles und maxillae. The necessary stability of the head capsule is provided by the hypostomal bridge which also compensates the far-reaching reduction of the tentorium.     

Phylogenetic analysis of Trechitae (Coleoptera: Carabidae) based on larval morphology, with a description of first-instar Phrypeus and a key to genera

Abstract. Sixty-nine characters of larval structure of twenty-eight genera of the supertribe Trechitae (Coleoptera: Carabidae) were analysed phylogenetically. The monophyly of Trechitae is strongly supported with five unique synapomorphies. The monophyly of Zolini + Bembidiini + Pogonini is supported with two synapomorphies. We propose that the tribe Trechini is a sister group to them and its monophyly is supported with two unique synapomorphies. The inferred branching pattern of Trechini genera is (Perileptus + Thalassophilus) + (Amblystogenium + (Trechimorphus + (Trechus + Epaphius + Aepopsis + Trechisibus))); Perileptus is a member of Trechodina rather than Trechina. The monophyly of Zolini is not supported. The monophyly of Pogonini is supported with two unique synapomorphies; its sister group relationships remain obscure; the branching pattern of pogonine genera is (((Pogonus + Pogonistes) + Cardiaderus) + Thalassotrechus). No evidence for monophyly of the tribe Bembidiini (s. lato; including subtribes Bembidiina, Tachyina, Xystosomina, and Anillina) was found. The relationships of Phrypeus are obscure; no evidence could be found linking it with Bembidiina. Without Phrypeus, Bembidiina might be a monophylum with a single synapomorphy. Sinechostictus branches basal of (Bembidion + Asaphidion) and therefore should be treated as a separate genus. Tachyina and Xystosomina form a monophylum based on two unique synapomorphies; a close relationship with a monophyletic Anillina is suggested. Reduction of the number of claws from two to one in Trechitae has taken place twice: within Trechina (Trechus, Epaphius, Aepopsis and Trechisibus) and in (Zolini + Bembidiini + Pogonini). The previously unknown larvae of the isolated genus Phrypeus are described and illustrated. A key to all twenty-eight analysed Trechitae genera based on characters of larvae and a list of larval autapomorphies for each genus are provided.