Head structures of Karoophasma sp. (Hexapoda, Mantophasmatodea) with phylogenetic implications

External and internal head structures of adults of Karoophasma sp. were examined and described. The results are compared with conditions found in other representatives of Mantophasmatodea and members of other lower neopteran groups. The X-shaped apodeme of the frons, the unpigmented oval area enclosed by apical branches of the anterior tentorial arms, the oval sclerotisation at the base of the labrum, the sclerotized rounded apical part of the galea, and the loss of M. labroepipharyngalis are probably autapomorphic for Mantophasmatodea. Plesiomorphic features (groundplan of Neoptera) are the orthognathous condition, the absence of parietal ridges, the absence of a gula, the absence of a 'perforation of the corpotentorium', the multisegmented antennae inserted between the compound eyes, the general arrangement of the mouthparts, the shape and composition of the maxillae and labium, and the nearly complete set of muscles. The presence of a transverse muscle connecting the antennal ampullae is a potential synapomorphy of Orthoptera, Phasmatodea and Dictyoptera. Character states suggesting affinities with Grylloblattodea are the absence of ocelli, the elongation of the corpotentorium, and the very similar mandibles with widely separated bases and completely reduced molae. Whether predacious habits are a synapomorphic feature of Mantophasmatodea and Grylloblattodea is uncertain. The retained orthognathous condition in Mantophasmatodea and Mantodea is likely related with different specialized preying techniques in both groups, i.e. rapid forward pushes of the head–prothorax complex, and the use of raptorial legs, respectively.     

Microstructure of mandibulate mouthparts in the greater rice weevil,Sitophilus zeamais (Coleoptera: Curculionidae)

The greater rice weevil, Sitophilus zeamais, is a serious pest of stored grain. It chews a hole in the grain and deposits an egg inside. For the purpose of excavating a tunnel, these weevils are equipped with effective mandibulate mouthparts for penetrating and boring holes. The mouthparts of the weevil are a long slender snout, which consist of a labrum, a pair of mandibles, a pair of maxillae and a labium. Mothparts exhibit typical morphology of phytophagous coleopteran beetles and have characteristics of chewing mouthparts. Mandibles are connected to the head capsule through dicondyous articulation, which allows movement along one single rotating axis. Both labrum and labium are fused to the snout and form the upper and lower lips, respectively. Along the depressed surface of the snout, a number of short sensory hairs are sparsely arranged. The distal apexes of the maxillary and labial palpi are deeply depressed into a sensillar field, and only one type of the basiconic sensilla, which function as chemo‐ or gustatory receptors, occurs in both sexes.     

Functional Morphology and Sexual Dimorphism of Mouthparts of the Short-Faced Scorpionfly Panorpodes kuandianensis (Mecoptera: Panorpodidae)

Mouthparts are closely associated with the feeding behavior and feeding habits of insects. The features of mouthparts frequently provide important traits for evolutionary biologists and systematists. The short-faced scorpionflies (Panorpodidae) are distinctly different from other families of Mecoptera by their extremely short rostrum. However, their feeding habits are largely unknown so far. In this study, the mouthpart morphology of Panorpodes kuandianensis Zhong et al., 2011 was investigated using scanning electron microscopy and histological techniques. The mandibulate mouthparts are situated at the tip of the short rostrum. The clypeus and labrum are short and lack distinct demarcation between them. The epipharynx is furnished with sublateral and median sensilla patches. The blade-shaped mandibles are sclerotized and symmetrical, bearing apical teeth and serrate inner margins. The maxilla and labium retain the structures of the typical pattern of biting insects. The hirsute galea, triangular pyramid-shaped lacinia, and labial palps are described in detail at ultrastructural level for the first time. Abundant sensilla are distributed on the surface of maxillary and labial palps. The sexual dimorphism of mouthparts is found in Panorpodes for the first time, mainly exhibiting on the emargination of the labrum and apical teeth of mandibles. Based on the features of mouthparts, the potential feeding strategy and feeding mechanism are briefly discussed in Panorpodes.     

The mouthparts of cockroaches (Blattodea)

The structure of the mouthparts was studied in 24 species representing 10 families and 4 suborders of cockroaches. The details of the labrum, mandibles, maxillae, labium, and hypopharynx, characteristic of different suborders of Blattodea and some families of Blaberoidea, were revealed.     

The embryonic development of Stylops ovinae (Strepsiptera,Stylopidae) with emphasis on external morphology

External features of the embryonic development of Stylops ovinae (Strepsiptera) were examined. Eighteen distinct embryological stages are suggested. Many embryological traits are closely correlated to the parasitic life style of the first instar larvae or to vivipary. The high number of eggs, their small size, the characteristic egg membrane, and the lack of micropyles are derived groundplan features of Strepsiptera. The development with a semi-long germ embryo is shared with several other groups of Holometabola. The reduction of the labrum and antennae are autapomorphies of Strepsiptera. The cephalic ventral plate of the first instar larva of S. ovinae is formed by parts of the head capsule and the anlagen of the maxillae and labium. It is involved in the formation of the specific entognathous condition, and the entire character complex is autapomorphic for Stylopidae. The trochanter is recognizable in the anlagen of all three legs. Its fusion with the femur in the later stages is an autapomorphy of Stylopidia. The extreme spiralization and compression of the abdomen during blastokinesis is a derived feature, like the reduction of the anlagen of the anterior abdominal appendages. The caudal bristles on segment XI are possibly re-activated cerci. The same is likely in the case of segment XI.     

Mouthpart and foregut ontogeny in larval, postlarval, and juvenile spiny lobster, Panulirus argus Latreille (Decapoda, Palinuridae)

The spiny lobster Panulirus argus has a life cycle consisting of a long-term (～9-12 months) planktonic larval period with 11 larval stages (the phyllosoma), a short (<1 month?) planktonic-to-benthic transitional postlarval stage (the puerulus), and benthic juvenile and adult phases. The mouthparts and foregut during these stages were examined and described by means of scanning electron microscopy (SEM) in an investigation of the species' developmental morphology, diet, and ecology. The phyllosoma mouthparts close to the esophagus are the labrum, mandibles, paragnaths, and first maxillae. The second maxillae and first and second maxillipeds are increasingly distant from the esophagus as the larva develops. The pair of asymmetrical mandibles bear many teeth and spines, and the molar processes form what appears to be an intricate toothed shear. The mandibles remain similar throughout the phyllosoma stages. During the molt into the puerulus, the mouthparts are greatly changed, and the second maxilla and the three maxillipeds join the other mouthparts near the esophagus. However, the transformation appears incomplete, and many of the mouthparts are not fully formed until the molt to juvenile completes their development. The phyllosoma foregut lacks a gastric mill and has but one chamber. In addition, the first two stages lack a gland filter. During the molt to puerulus, the foregut is greatly changed and subsequently is similar to typical decapod foreguts in having an anterior cardiac and posterior pyloric chamber. Only rudimentary internal armature is present. Following the molt to juvenile, the foregut is quite similar to that of the adult, which exhibits a substantial gastric mill. The 11 phyllosoma stages were separated into two groups (group A = stages 1-5, group B = stages 6-11) on the basis of changes in both mouthpart and foregut morphology. The puerulus has never been observed to feed. Nothing was observed in our investigations that would prevent feeding, though both mouthpart and foregut development appeared incomplete. The mouthpart and foregut structures of larval, postlarval and juvenile P. argus differ widely, possibly reflecting the extreme modifications for different habitats found among these life phases.     

Male Weaponry in a Fighting Cricket

Sexually selected male weaponry is widespread in nature. Despite being model systems for the study of male aggression in Western science and for cricket fights in Chinese culture, field crickets (Orthoptera, Gryllidae, Gryllinae) are not known to possess sexually dimorphic weaponry. In a wild population of the fall field cricket, Gryllus pennsylvanicus, we report sexual dimorphism in head size as well as the size of mouthparts, both of which are used when aggressive contests between males escalate to physical combat. Male G. pennsylvanicus have larger heads, maxillae and mandibles than females when controlling for pronotum length. We conducted two experiments to test the hypothesis that relatively larger weaponry conveys an advantage to males in aggressive contests. Pairs of males were selected for differences in head size and consequently were different in the size of maxillae and mandibles. In the first experiment, males were closely matched for body size (pronotum length), and in the second, they were matched for body mass. Males with proportionately larger weaponry won more fights and increasing differences in weaponry size between males increased the fighting success of the male with the larger weaponry. This was particularly true when contests escalated to grappling, the most intense level of aggression. However, neither contest duration nor intensity was related to weaponry size as predicted by models of contest settlement. These results are the first evidence that the size of the head capsule and mouthparts are under positive selection via male-male competition in field crickets, and validate 800-year-old Chinese traditional knowledge.     

External microstructure of the ambrosia beetle Platypus koryoensis (Coleoptera: Curculionidae: Platypodinae)

Platypus koryoensis is a minute ambrosia beetle found in forests. It can cause significant economic damage to oak trees. Recently in Korea, it has been reported as a major pest of oak trees, because it causes sooty mold of oak by introducing the pathogenic fungus Raffaelea sp. In this paper, we demonstrate the fine structural aspects of the external body of the ambrosia beetle using field emission scanning electron microscopy, as a part of basic research into this pest so that strategies for its control might be developed. This beetle has a sensory system well developed to respond to both visual and chemical stimuli. Both sexes have a pair of faceted compound eyes and a pair of knobbed antennae, but simple eyes are absent. The mouthparts on its distinct snouts are effective devices for penetration and for boring holes. The mouthparts consist of the labrum, a pair of mandibles, a pair of maxillae and the labium. Both the maxillary and the labial palpi have the function of directing the food to the mouth and holding it while the mandibles chew the food. The distal ends of these palpi are flattened and have shovel‐like setae. The thorax has a particularly hard exoskeleton and hard elytra, including powerful muscles that operate both the wings and the legs. The legs are multi‐segmented and have a strong femur and tibia, including one pair of claws on the end of each tarsal segment. Characteristically, both male and female beetles have mycangial cavities for storing spores and other microorganisms, but only females have three pairs of large depressions on their dorsal thorax.     

Fine structure and functional morphology of the mouthparts of Bittacus planus and Terrobittacus implicatus (Insecta: Mecoptera: Bittacidae)

The Bittacidae are unique in Mecoptera for their adults being predaceous. However, their mouthparts have not been well documented for functional morphology to date. Here, we investigated the mouthpart morphology of the hangingflies Bittacus planus Cheng and Terrobittacus implicatus (Huang & Hua) using scanning electron microscopy. The mouthparts are of the mandibulate type and situated at the tip of an elongated rostrum. The labrum is greatly elongated, roughly twice as long as the subquadrate clypeus. The epipharynx is furnished with a row of basiconic sensilla arranged evenly as a median band extending from the apex to the base. The mandibles are slender and elongated, bearing a sharp lateral and a small mesal tooth. The maxillae are well developed, each consisting of a partially sclerotized cardo and a stipes, a hirsute galea and a lacinia, and a five-segmented maxillary palp. The sensillar pattern on the distal segment of the maxillary palp differs slightly between the two bittacid species. The labium is composed of a postmentum, a prementum, and a pair of two-segmented labial palps. The feeding mechanism of bittacids is briefly discussed in combination with the mouthpart morphology and their feeding habits.     

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.     

Morphology of the mouthparts of the spittlebug Philagra albinotata Uhler (Hemiptera: Cercopoidea: Aphrophoridae)

Mouthparts associated with feeding behavior and feeding habits are important sensory and feeding structures in insects. To obtain a better understanding of feeding in Cercopoidea, the morphology of mouthparts of the spittlebug, Philagra albinotata Uhler was examined using scanning electron microscopy. The mouthparts of P. albinotata are of the typical piercing–sucking type found in Hemiptera, comprising a cone-shaped labrum, a tube-like, three-segmented labium with a deep groove on the anterior side, and a stylet fascicle consisting of two mandibular and two maxillary stylets. The mandibles consist of a dorsal smooth region and a ventral serrate region near the apical half of the external convex region, and bear five nodules or teeth on the dorsal external convex region on the distal extremity; these are regarded as unique features that distinguish spittlebugs from other groups of Hemiptera. The externally smooth maxillary stylets, interlocked to form a larger food canal and a smaller salivary canal, are asymmetrical only in the internal position of longitudinal carinae and grooves. One dendritic canal is found in each maxilla and one in each mandible. Two types of sensilla trichodea, three types of sensilla basiconica and groups of multi-peg structures occur in different locations on the labium, specifically the labial tip with two lateral lobes divided into anterior sensory fields with ten small peg sensilla arranged in a 5 + 4 + 1 pattern and one big peg sensillum, and posterior sensory fields with four sensilla trichodea. Compared with those of previously studied Auchenorrhyncha, the mouthparts of P. albinotata may be distinguished by the shape of the mandibles, the multi-peg structures and a tooth between the salivary canal and the food canal on the extreme end of the stylets. The mouthpart morphology is illustrated using scanning electron micrographs, and the taxonomic and putative functional significance of the different structures is briefly discussed.     

Diagnosis, classification, and phylogenetic relationships of the orphnine scarab beetles (Coleoptera, Scarabaeidae: Orphninae)

Orphnine scarab beetles (Orphninae) are widely distributed in the tropical and subtropical regions of the southern continents except for Australia. The catalogue of nominal taxa of orphnines includes 2 tribes, 15 genera, and 195 species. Diagnosis of the group, based on adult morphological characters, is as follows: antennae 10-segmented with 3-segmented club; mandibles with 2?C4 scissorial teeth and well developed mola; labrum and mandibles protruding past clypeus and visible from above; scutellum well developed in winged species, reduced but distinct in wingless species; wings with distinct anal area; apices of anterior tibia in males without spur but normally with a few robust setae; anterior coxa with longitudinal hollow on anterior surface; tarsi with 2 similar claws; middle and hind tibiae with 2 apical spurs; abdominal sternite 2 with sub-triangular to rounded plectrum; dorsal surface of hind coxae with oval flat stridulatory file; pygidium partly hidden under elytra; parameres symmetrical; bursa copulatrix sacciform, membranous; spermatheca C-shaped, not sclerotized; accessory vaginal glands developed; abdomen with 2 sclerotized tergites (VII?CVIII) and 6 visible sternites (III?CVIII). Preliminary phylogenetic analysis based on 47 characters of adult morphology shows that the tribe Aegidiini Paulian is a natural, monophyletic group. The genus Stenosternus Karsch described from a single specimen from S?o Tomé Island (Gulf of Guinea), is morphologically more similar to the New World taxa than to the Old World ones and is provisionally placed in Aegidiini. The tribe Orphnini Erichson seems non-monophyletic and has no synapomorphies. The genus Orphnus is apparently a polyphyletic group and it needs taxonomic revision. The hypothesis on sister-group relationship of Orphninae and Allidiostomatinae, based on molecular data, is not supported by the morphological characters. The stridulatory organs (the putative synapomorphy of Orphninae + Allidiostomatinae) are not identical in these groups; the mouthparts and female genitalia are essentially different. Orphninae have chewing mouthparts with large scissorial teeth and well developed mola, which is characteristic of generalist saprophagous species. Allidiostomatinae have mandibles with scissorial teeth and mola reduced; they also have sclerotized bursa copulatrix and sclerotized mandibular duct which opens on the dorsal side near condyle. Considering the present day development of alpha-taxonomy of most orphnine taxa, especially the speciose genus Orphnus, it seems premature to propose changes in higher classification of the subfamily. To clarify the phylogenetic position of the Orphninae among scarab beetles it is essential to include representative members of all taxa of orphnine lineage (sensu Browne, Scholtz, 1998) into the analysis.     

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.     

The larval head of Agathiphaga (Lepidoptera, Agathiphagidae) and the lepidopteran ground plan

Abstract. The larval head of Agathiphaga vitiensis is described. There is a complete hypostomal bridge but no hypostomal ridges. Adfrontal ridges and distinct ecdysial lines are absent. There are two vestigial stemmata (without lenses) on each side. The antenna is one-segmented. All ‘typical lepidopteran’ head setae have been identified. The corporotentorium is very slender; dorsal tentorial arms are present. Intrinsic labral muscles are lacking. The mandible has retained a tentorial muscle. The maxilla is without a discrete cardo and has but a single endite lobe; ‘intrinsic maxillary muscles’ and the ‘cranial flexor of the dististipes’ are lacking. The postlabium is undivided and without setae, the labial palp is one-segmented and the lateral prelabio-hypopharyngeal sclerotization is continued into an oral arm. Some of the ventral pharyngeal dilators arise on the tentorium; mouth-angle retractors and dorsal post-cerebral pharynx dilators are absent. The two brain lobes have almost parallel long axes and are united by a narrow (almost pure neuropile) bridge. The corpora cardiaca and callata are contiguous. The aorta is an open gutter in front of the retrocerebral complex. Available evidence on the ground plan structure of the lepidopteran larval head is reviewed. The ancestral head supposedly was prognathous and was autapomorphic in having the cranio-cardinal articulation far behind the mandible; it had a complete hypostomal bridge but neither hypostomal nor adfrontal ridges, its tentorium was probably stout and with dorsal arms. Paulus & Schmid (1978, Z. zool. Syst. EvolForsch. 16) described a lepidopteran/trichopteran synapomorphy in stemma structure. A tentative table of homologies between cranial setae in Lepidoptera and Trichoptera is presented; it differs considerably from the scheme of Williams & Wiggins (1981, Proc. 3rd Symp. Trichopt.). The mouth parts and their musculature must have been overall very primitive for a panorpid larva, but the number of maxillary palp segments was reduced (three). The ‘dististipes’sensu Hinton is considered to consist of complexly fused parts of the stipes and basal palp segments. The cephalic stomodaeum must have possessed all primitive groups of extrinsic muscles. The incomplete available information on Micropterigidae impedes reconstruction of some details of the lepidopteran ground plan. Larval head structures support the monophyly of an entity comprising the Agathiphagidae + Heterobathmiidae + Glossata. There is one suite of derived characters shared by Heterobathmiidae and Agathiphagidae only and another shared by Heterobathmiidae and the Glossata only; one of these must represent parallelisms.     

Development of the mouthparts in embryos of Haplothrips verbasci (Osborn) (Insecta,Thysanoptera, Phlaeothripidae)

The asymmetric “punch and suck” mouthparts of larval Haplothrips verbasci develop from paired appendages in the late, post-anatrepsis embryo similar to those of other insects. Later, the labrum flexes ventrally over the stomodaeum, the right mandibular appendage degenerates, the maxillary appendages divide into inner (lacinial) and outer (stipital) lobes, and the hypopharynx arises from the venters of the mandibular and maxillary segments. All cephalic segments consolidate anteriorly prior to katatrepsis, their appendages flex ventrally, and the labial appendages fuse medially to form the labium and the primordia of the salivary glands and valve. The left mandible and the lacinial lobes of the maxillae invaginate into the head during and after katatrepsis to form the mandibular and maxillary stylet-secreting organs and these later deposit the cuticle of their respective stylets. Cuticle of the mandibular lever is deposited by labral cells at the apex of the mandibular sheath during and after hatching. That of each maxillary lever is secreted simultaneously into the lumen of a ventrally-directed diverticulum developing from stipital cells at the apex of each maxillary sheath. Shortly after katatrepsis, the maxillary and labial palpi originate respectively from cells in the outer wall of each stipital lobe and at the apex of the labium. Muscles of the mouthparts arise after katatrepsis from cephalic mesoderm and are fully-differentiated before cuticle of the mandibular and maxillary levers has been deposited. Gnathal morphogenesis in embryos of H. verbasci resembles that occurring in bug embryos and provides additional evidence that Thysanoptera and Hemiptera evolved from a common psocopteroid stem species having small, paired, biting and chewing mandibles and well developed lacinial stylets.     

The larval head morphology of Xyela sp. (Xyelidae, Hymenoptera) and its phylogenetic implications

Larval head structures of Xyela sp. are described in detail. The characters are compared to conditions found in larvae of other groups of Hymenoptera and Endopterygota. Like other symphytan larvae the immature stages of Xyelidae are mainly characterized by presumably plesiomorphic features of the head. The head sutures are well developed and all parts of the tentorium are present. The labrum is free and a complete set of labral muscles is present. The maxillae are in a retracted position. In contrast to other hymenopteran larvae Xyela possesses a clypeofrontal suture, a comparatively long antenna and three well‐developed antennal muscles. Apomorphic features of Xyela are the absence of muscles associated with the salivarium and the complete absence of Musculus craniocardinalis. A clade comprising Orussidae and Apocrita is supported by the unsegmented maxillary and labial palps and the absence of the lacinia. Six potential autapomorphies for the Hymenoptera were revealed: (1) the caudal tentorial apodeme, (2) the bifurcated tendon of Musculus craniomandibularus internus, (3) the lateral lobe of the cardo, (4) the origin of M. tentoriohypopharyngalis from the posterior head capsule, (5) the exceptionally strong prepharyngo‐pharyngeal longitudinal muscle and (6) the longitudinal muscle of the silk press. The maxillolabial complex, the vestigial M. craniocardinalis and a distinctly developed labio‐hypopharyngeal lobe bearing the opening of the salivary duct are potential synapomorphies of Hymenoptera and Mecopterida. The globular, orthognathous head capsule, the modified compound eyes, the occipital furrow and the X‐shaped tentorium are features with unclear polarity shared by Hymenoptera and Mecoptera.     

Feeding mechanisms, and their variation in form, of some adult ground-beetles (Coleoptera: Caraboidea)

The structure of the mouthparts and foregut of some caraboid beetles has been correlated with their type of feeding mechanism. These may be adapted to fragmentary feeding, fluid feeding (where pre-oral digestion is important), or to mixed feeding (a large category which ranges from a mainly fluid to a mainly solid intake). Head structures concerned with feeding have been discussed in relation to these methods; they include the mandibles, maxillae, labrum-epipharynx and anterior foregut, proventriculus, labium-hypopharynx and the head floor. Different types of head floor were denned in relation to gular structure, in particular the presence or absence of the mid-gular apodeme. Convergent evolution of feeding mechanisms was noted amongst both fragmentary feeders and fluid feeders; in the latter group, sucking pumps have been evolved in the Carabitae, Scarites , Cicindelidae, Paussini and some other caraboids. It was suggested that head shape in caraboids may reflect locomotory adaptations more frequently than feeding adaptations.     

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.     

The cephalic morphology of the troglobiontic cholevine species Troglocharinus ferreri (Coleoptera,Leiodidae)

Leiodidae are the second largest subterranean radiation of beetles at family rank. To explore morphological trends linked with troglobiontic habits and characters with potential phylogenetic significance, the head of the cave-dwelling species Troglocharinus ferreri (Cholevinae, Leptodirini) was examined in detail. Overall, the general pattern is similar to what is found in Catops ventricosus (Cholevini). Shared apomorphic features include a fully exposed anterolateral concavity containing the antennal socket, a distinct bead above this depression, a bilobed lip-like structure anterad the labrum, a flat elevated portion of the ventral mandibular surface, and a ventral process at the proximomesal edge of this mandibular area. The tentorial structures are well-developed as in C. ventricosus, with a large laminatentorium and somewhat shortened dorsal arms. The mouthparts are largely unmodified, with the exception of unusually well-developed extrinsic maxillary muscles. Features of T. ferreri obviously linked with subterranean habits are the complete lack of compound eyes, circumocular ridges, and optic lobes. A series of characters is similar to conditions found in other genera of Leptodirini: the head capsule completely lacks a protruding ocular region, a distinct neck is missing, the transverse occipital crest is indistinct, and the antennae are elongate and lack a distinct club. Two different trends of cephalic transformations occur in troglobiontic Leptodirini, with some genera like Troglocharinus and Leptodirus having elongated head capsules and antennae, and others having broadened, more transverse heads. In contrast, the modifications are more uniform in the closely related Ptomaphagini, with a pattern distinctly differing from Leptodirini: the head is transverse, with a distinctly protruding ocular region, a distinct transverse occipital crest, and a very narrow neck region.     

Position and definition of the genus Paegniodes Eaton, 1881 based on redescription on the type species Paegniodes cupulatus (Eaton, 1871) (Ephemeroptera: Heptageniidae)

The genus Paegniodes Eaton, 1881 and its type species P. cupulatus (Eaton, 1871) have never been described in detail completely. In this article, all stages are described and photographed. Compared to other heptageniid genera, the adults of P. cupulatus have a more colourful body, smaller hindwings but larger titillators. The nymphs of this species have no setae or tubercles on the body and no emarginations on the head capsule. They have smaller lamellae of the first gills, a wider labrum with a median notch, mandibles without setae on outer margins, maxillae with a row of setae and scattered setae on the ventral surface, cerci with mesal setae, and a median filament with setae on both sides. Both imaginal and nymphal stages of the genus have unique characters, so the taxon Paegniodes is recognized at the rank of genus here. It appears closely related to Rhithrogena Eaton, 1881.