Mouthparts and stylet penetration of the lac insect Kerria lacca (Kerr) (Hemiptera:Tachardiidae)

Hitherto less known aspects on mouthpart morphology and penetration mechanism of the lac insect Kerria lacca have been explored. Unique details of the mouthparts, i.e. morphology of labium and stylets and salivary sheath have been brought out. The gross morphology of the mouthparts though resembled other plant sucking homopterans; a two-segmented labium with symmetrically distributed six pairs of contact-chemoreceptors on its surface was distinct; the mandibular stylets had serrations on its extreme apical region, while the maxillary stylets had their external surface smooth with parallel longitudinal grooves on their inner surface. Formation of flanges, salivary sheath and penetration pathway observed along with probing and penetration of the stylets intracellularly up to the phloem cells, as illustrated herein, are the addition to the existing knowledge on the structural details of the mouthparts and the feeding behavior thereupon.     

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.     

Utility of geometric morphometrics for inferring feeding habit from mouthpart morphology in insects: tests with larval Carabidae (Insecta: Coleoptera)

Feeding habits are important life‐history traits in animals; however, methods for their determination are not well established in many species. The larvae of the beetle family Carabidae are an example. The present study tested the utility of geometric morphometrics of mouthpart morphology to infer the feeding habits of carabid larvae. Using Pterostichus thunbergi as a model system, larval feeding habits were inferred using geometric morphometrics of mouthparts and the results were compared with those obtained from rearing experiments. The rearing experiments indicated that P. thunbergi larvae are carnivores that require snails as an essential part of the diet. Through geometric morphometrics, associations between mouthpart morphology and larval feeding habits were confirmed for species in which these two traits are known. A discriminant analysis using these associations classified P. thunbergi larvae as snail/slug feeders, which is a result compatible with the rearing experiments. Geometric morphometrics also revealed that morphological integration and ontogenetic shape change might play roles in the diversification of mouthpart morphology. Overall, these results demonstrate the utility of the geometric morphometrics of mouthparts to infer feeding habit and to clarify the mechanisms of mouthpart morphological diversification in the study group, and the results also serve as a basis for future studies of other insect groups.     

Fine structure and sensory apparatus of the mouthparts of the pear psyllid,Cacopsylla chinensis (Yang et Li) (Hemiptera: Psyllidae)

The pear psyllid, Cacopsylla chinensis (Yang et Li) (Hemiptera: Psyllidae), is one of the most significant economic pests of pear in China, causing direct damage through feeding by the highly specialized piercing–sucking mouthparts. The ultrastructural morphology and sensory apparatus of the mouthparts of the adult were examined using scanning and transmission electron microscopy. The piercing–sucking mouthparts of C. chinensis are composed of a three-segmented labium with a deep groove in the anterior side, a stylet fascicle consisting of two mandibular and two maxillary stylets, and a pyramid-shaped labrum. Proximal to the labium, the stylet fascicle forms a large loop within a membranous crumena. Mandibles, with more than ten teeth on the external convex region, can be seen on the distal extremity. Smooth maxillary stylets are interlocked to form a larger food canal and a smaller salivary canal. One dendritic canal housing 2 dendrites is also found in each mandible. Two types of sensilla trichodea, four types of sensilla basiconica, single as well as groups of sensilla campaniformia, and oval flattened sensilla occur in different locations on the labium, whereas a kind of sensilla basiconica is at the junction of the labrum and anteclypeus. Sensilla trichodea and sensilla campaniformia, always present with denticles, are present on the middle labial segment. Three types of sensilla basiconica, two types of sensilla trichodea and two oval flattened sensilla are located on the distal labial segment. The mouthpart morphology and abundance of sensilla located on the labium in C. chinensis are illustrated, along with a brief discussion of their taxonomic and putative functional significance.     

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.     

Acanthodiaptomus denticornis another omnivorous calanoid copepod: description of its mouth appendages and feeding experiments on animal prey

The mouthpart morphology of the freshwater calanoid copepod Acanthodiaptomus denticornis was examined with optical microscopy. The mouthparts have sharp teeth and stout appendages with clawlike setae, typical of omnivorous calanoid mouthpart morphology. Observation of the buccal aperture with Scanning Electron Microscopy shows a large opening permitting feeding on prey as large as Keratella cochlearis. These observations agree with our feeding experiments which show that A. denticornis feed on K. cochlearis.     

The mouth apparatus of Lithodes maja (Crustacea: Decapoda) – form,function and biological role

Being able to utilize many different food resources is probably an important aspect of the success of decapod crustaceans which fill a wide range of various ecological niches worldwide. The phenomenon is facilitated by the complex mouth apparatus found in this group, whose representatives possess six pairs of mouthparts– mandibles, maxillae 1, and maxillae 2 and three maxillipeds, the first three pairs of thoracic appendages which are also specialized to food manipulation. These six pairs are able to perform a number of movements for transporting, aligning, crushing and cutting. Studies into the functional morphology of mouthparts have already been carried out in some decapod species. This study focuses on Lithodes maja, a species of the hitherto understudied king crabs (Lithodidae), chosen on the grounds of their remarkable evolutionary history as ‘derived hermit crabs’. Individuals were filmed while being presented with different kinds of food. To obtain structural information on the individual mouthpart elements as naturally arranged in relation to one another, the shape of the mouthparts was 3D‐reconstructed from micro‐CT scans. These data were complemented by scanning electron microscopy, to analyse the surface structures in detail. There is evidence that the various elements of the mouthparts of L. maja can be sorted into six functional groups: (i) transporting mouthpart elements, (ii) aligning/sorting mouthpart elements, (iii) clutching/holding mouthpart elements, (iv) tearing/cutting/crushing mouthpart elements, (v) current‐generating mouthpart elements and (vi) grooming mouthpart elements. According to our 3D reconstruction, there only seem to be minor differences in morphology and relative position between the mouthparts of L. maja and those of the closely related species, Pagurus bernhardus.     

Characterization of a ligand-gated cation channel based on an inositol receptor in the silkworm,Bombyx mori

Insect herbivores recognize non-volatile compounds in plants to direct their feeding behavior. Gustatory receptors (Gr) appear to be required for nutrient recognition by gustatory organs in the mouthparts of insects. Gr10 is expressed in Bombyx mori (BmGr10) mouthparts such as maxillary galea, maxillary palp, and labrum. BmGr10 is predicted to function in sugar recognition; however, the precise biochemical function remains obscure. Larvae of B. mori are monophagous feeders able to find and feed on mulberry leaves. Soluble mulberry leaf extract contains sucrose, glucose, fructose, and myo-inositol. In this study, we identified BmGr10 as an inositol receptor using electrophysiological analysis with the Xenopus oocyte expression system and Ca²⁺ imaging techniques using mammalian cells. These results demonstrated that Xenopus oocytes or HEK293T cells expressing BmGr10 specifically respond to myo-inositol and epi-inositol but do not respond to any mono-, di-, or tri-saccharides or to some sugar alcohols. These inositols caused Ca²⁺ and Na⁺ influxes into the cytoplasm independently of a G protein-mediated signaling cascade, indicating that BmGr10 is a ligand-gated cation channel. Overall, BmGr10 plays an important role in the myo-inositol recognition required for B. mori larval feeding behavior.     

Chemosensory neurons in the mouthparts of the spiny lobsters Panulirus argus and Panulirus interruptus (Crustacea: Decapoda)

We studied electrophysiological properties of single chemosensory neurons in the mouthparts of the spiny lobsters Panulirus argus and Panulirus interruptus to complement our growing understanding of the behavioral roles of mouthparts of decapod crustaceans. Food mixtures and 13 single compounds were used to characterize the response specificity, sensitivity, and time course of individual neurons in the endopods of maxilliped 2 and 3. Additional chemoreceptors were found in the mandibular palp and basis of maxilliped 1 but they were not characterized. Neurons were broadly tuned, with the five most potent single compounds being ammonium, adenosine-5′-monophosphate, taurine, glutamate, and aspartate. Cluster analysis indicated that the neurons constitute a heterogeneous population that could be placed into seven groups linked according to their most excitatory compound. These neurons in the mouthparts had concentration-dependent responses, with thresholds between 10⁻⁷ and 10⁻⁴ M and without saturation even at 10⁻³ or 10⁻² M. They also quickly adapted when exposed to their best compounds at 10⁻⁴ and 10⁻³ M. A comparison of the response properties of these neurons in the mouthparts with those of chemosensory neurons in other crustacean appendages shows that neurons in the mouthparts have relatively broad tuning biased toward detecting and resolving high concentrations. Based on these comparisons, we suggest a functional distinction among the chemosensors on the different appendages: long distance detection by the antennae, precise location and collection by the pereiopods, and detailed assessment of quality by the mouthparts.     

Drinking with a very long proboscis: Functional morphology of orchid bee mouthparts (Euglossini,Apidae, Hymenoptera)

Neotropical orchid bees (Euglossini) possess the longest proboscides among bees. In this study, we compared the feeding behavior and functional morphology of mouthparts in two similarly large-sized species of Euglossa that differ greatly in proboscis length. Feeding observations and experiments conducted under semi-natural conditions were combined with micro-morphological examination using LM, SEM and micro CT techniques. The morphometric comparison showed that only the components of the mouthparts that form the food tube differ in length, while the proximal components, which are responsible for proboscis movements, are similar in size. This study represents the first documentation of lapping behaviour in Euglossini. We demonstrate that Euglossa bees use a lapping-sucking mode of feeding to take up small amounts of fluid, and a purely suctorial technique for larger fluid quantities. The mouthpart movements are largely similar to that in other long-tongued bees, except that the postmentum in Euglossa can be extended, greatly enhancing the protraction of the glossa. This results in a maximal functional length that is about 50% longer than the length of the food canal composing parts of the proboscis. The nectar uptake and the sensory equipment of the proboscis are discussed in context to flower probing.     

Structural mouthpart interaction evolved already in the earliest lineages of insects

In butterflies, bees, flies and true bugs specific mouthparts are in close contact or even fused to enable piercing, sucking or sponging of particular food sources. The common phenomenon behind these mouthpart types is a complex composed of several consecutive mouthparts which structurally interact during food uptake. The single mouthparts are thus only functional in conjunction with other adjacent mouthparts, which is fundamentally different to biting–chewing. It is, however, unclear when structural mouthpart interaction (SMI) evolved since this principle obviously occurred multiple times independently in several extant and extinct winged insect groups. Here, we report a new type of SMI in two of the earliest wingless hexapod lineages—Diplura and Collembola. We found that the mandible and maxilla interact with each other via an articulatory stud at the dorsal side of the maxillary stipes, and they are furthermore supported by structures of the hypopharynx and head capsule. These interactions are crucial stabilizing elements during food uptake. The presence of SMI in these ancestrally wingless insects, and its absence in those crustacean groups probably ancestral to insects, indicates that SMI is a groundplan apomorphy of insects. Our results thus contradict the currently established view of insect mouthpart evolution that biting–chewing mouthparts without any form of SMI are the ancestral configuration. Furthermore, SMIs occur in the earliest insects in a high anatomical variety. SMIs in stemgroup representatives of insects may have triggered efficient exploitation and fast adaptation to new terrestrial food sources much earlier than previously supposed.     

Patterning of the adult mandibulate mouthparts in the red flour beetle, Tribolium castaneum

Specialized insect mouthparts, such as those of Drosophila, are derived from an ancestral mandibulate state, but little is known about the developmental genetics of mandibulate mouthparts. Here, we study the metamorphic patterning of mandibulate mouthparts of the beetle Tribolium castaneum, using RNA interference to deplete the expression of 13 genes involved in mouthpart patterning. These data were used to test three hypotheses related to mouthpart development and evolution. First, we tested the prediction that maxillary and labial palps are patterned using conserved components of the leg-patterning network. This hypothesis was strongly supported: depletion of Distal-less and dachshund led to distal and intermediate deletions of these structures while depletion of homothorax led to homeotic transformation of the proximal maxilla and labium, joint formation required the action of Notch signaling components and odd-skipped paralogs, and distal growth and patterning required epidermal growth factor (EGF) signaling. Additionally, depletion of abrupt or pdm/nubbin caused fusions of palp segments. Second, we tested hypotheses for how adult endites, the inner branches of the maxillary and labial appendages, are formed at metamorphosis. Our data reveal that Distal-less, Notch signaling components, and odd-skipped paralogs, but not dachshund, are required for metamorphosis of the maxillary endites. Endite development thus requires components of the limb proximal-distal axis patterning and joint segmentation networks. Finally, adult mandible development is considered in light of the gnathobasic hypothesis. Interestingly, while EGF activity is required for distal, but not proximal, patterning of other appendages, it is required for normal metamorphic growth of the mandibles.     

Feeding behavior and related functional morphology of the mayflyEphemerella needhami (Ephemeroptera: Ephemerellidae)

The feeding behavior and functional morphology associated with feeding in Ephemerella needhamiMcDunnough larvae were studied using videomacroscopic techniques, gut content analysis, and scanning electron microscopy. Two stereotypic feeding cycles were employed by the larvae. In the maxillary brushing cycle, the maxillae are the primary food-gathering organs, with the main food being detritus deposited on the filamentous alga Cladophora.In the mandibular biting cycle, the mandibles are the primary food-gathering organs used to bite Cladophora filaments.Epiphytic diatoms on Cladophorawere another important part of the diet. Behavioral similarities are apparent in the choreography and synchronization of mouthpart movements among mayflies from several families. Functional morphological comparisons are drawn with hypognathous E. needhami, Cloeon dipterum, Baetis rhodani,and Siphlonurus aestivalis, aswell as the prognathous Heptageniidae. Differences in mouthpart usage and structure are related to the relative development of setal fields and combs and the feeding microhabitat.     

Morphological diversity of first instar larvae in Miltogramma subgenus Pediasiomyia (Diptera: Sarcophagidae, Miltogramminae)

The morphology of first instar larvae of three species of Miltogramma Meigen subgenus Pediasiomyia Rohdendorf is described using SEM and light microscope techniques. Miltogramma chrysochlamys (Rohdendorf), Miltogramma margiana (Rohdendorf) and Miltogramma przhevalskyi (Rohdendorf) share with other satellite flies the presence of an elongated sensillum basiconicum of the maxillary palpus and numerous longitudinal cuticular ridges on the integument of all segments; and they share with other Miltogramma spp. a maxillary palpus situated on a more or less raised base. While the first instar M. margiana is very similar to first instars of Miltogramma (sensu stricto), first instars of M. chrysochlamys and M. przhevalskyi share several features unique among Miltogramminae: antennal dome situated on a flat or indistinct basal ring, antennal dome flattened, border between pseudocephalon and first thoracic segment with a pair of fleshy processes, and basal ring with trichoid sensillum. First instars of M. chrysochlamys and M. przhevalskyi are unique in having both sb1 and sb2 of the sensilla basiconica of the maxillary palpus elongated, and M. przhevalskyi has an unpaired, median proleg on most abdominal segments.     

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.     

中华蚊蝎蛉成虫口器感器的超微结构

口器感器在昆虫取食活动中起着重要作用, 但蚊蝎蛉成虫口器上感器的种类和形态迄今未见报道。我们利用扫描电子显微镜, 观察了中华蚊蝎蛉Bittacus sinensis Walker成虫口器上的感器。结果显示: 中华蚊蝎蛉口器上共有8种感器, 分别为锥形、毛形、刺形、指形、掌状、钟形、柱状感器及Böhm氏鬃毛, 主要集中于内唇、 下颚须以及下唇须上。锥形感器和刺形感器数量最多; 毛形感器主要在下颚轴节、 茎节和下唇的亚颏和前颏有分布; 钟形感器和Böhm氏鬃毛只存在于下唇须和下颚须上。下颚须端节和下唇须端节的感器种类相同, 以锥形感器为主。高度骨化的上颚以及下颚内颚叶与外颚叶上未发现感器分布。简要讨论了口器感器在昆虫分类中的意义。     

Morphological description of the mouthparts of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae)

Scanning (SEM) and transmission (TEM) electron microscopy were used to elucidate the morphology of the rostrum, as well as the mandibular and maxillary stylets of the psyllid Diaphorina citri, vector of phloem-inhabiting bacteria associated with citrus huanglongbing (HLB) disease. D. citri has a cone-shaped rostrum that extends behind the pair of prothoracic coxae. The stylet bundle comprises a pair of mandibular (Md) and maxillary (Mx) stylets with a mean length of 513.3 μm; when retracted, their proximal portions form a loop and are stored in the crumena (Cr). Serial cross-sections of the rostrum revealed that the mandibles are always projected in front of the maxillary stylets. The two maxillary stylets form the food and salivary canals, with diameters of 0.9 μm and 0.4 μm respectively. These two canals merge at the end of the stylets forming a common duct with a length of 4.3 μm and a mean diameter of 0.9 μm. The acrostyle, a distinct anatomical structure present in the common duct of aphid maxillary stylets, was not observed by TEM in the ultrathin cross-sections of the common duct (CD) of D. citri. This study provides new information on D. citri mouthparts that may help to understand the feeding behaviour of this important vector of HLB-associated bacteria.     

Conservation and diversification of gene function during mouthpart development in Onthophagus beetles

The evolutionary success of insects is in part attributable to the tremendous diversification of their mouthparts, which permitted insects to radiate into novel food niches. The developmental genetic basis of mouthpart development has been well studied in at least two insect taxa possessing derived mouthparts, the hemipteran Oncopeltus fasciatus and Drosophila. However, much less is known about the regulation of mouthpart differentiation of the presumed ancestral mandibulate type. Here we aim to extend current insights into the patterning of mandibulate mouthparts through a functional genetic analysis of three leg gap genes, homothorax (hth), dachshund (dac), and Distal-less (Dll), in the dung beetle Onthophagus taurus, a species whose mouthpart arrangement has in part retained, as well as diverged form, the ancestral mandibulate mouthpart type. We specifically include in this study a first functional genetic analysis of the adult labrum, an enigmatic mouthpart whose appendicular origin has been the subject of a long-standing debate. Our results support a functional role of all three patterning genes in the development of the labium, maxilla, as well as the labrum. In contrast, mandible development appeared to rely only on the patterning functions of hth and dac, but not Dll. Here, our results raise the possibility that evolutionary changes in the dac-patterning may have played an important role in the evolutionary transition from a short, triangular mandible adapted for chewing to the elongated, flat, and blade-like mandible of modern filter-feeding scarabaeine beetles. In general, our results contribute to a growing body of studies that suggest that basic patterning genes can contribute to morphological evolution of adult features while maintaining traditional patterning responsibilities at earlier developmental stages or in other body regions.     

Profound head modifications in Claviger testaceus (Pselaphinae,Staphylinidae, Coleoptera) facilitate integration into communities of ants

Clavigeritae is a group of obligate myrmecophiles of the rove beetle subfamily Pselaphinae (Staphylinidae). Some are blind and wingless, and all are believed to depend on ant hosts through feeding by trophallaxis. Phylogenetic hypotheses suggest that their ancestors, as are most pselaphines today, were free-living predators. Morphological alterations required to transform such beetles into extreme myrmecophiles were poorly understood. By studying the cephalic morphology of Claviger testaceus, we demonstrate that profound changes in all mouthpart components took place during this process, with a highly unusual connection of the maxillae to the hypopharynx, and formation of a uniquely transformed labium with a vestigial prementum. The primary sensory function of the modified maxillary and labial palps is reduced, and the ventral mouthparts transformed into a licking/‘sponging’ device. Many muscles have been reduced, in relation to the coleopteran groundplan or other staphylinoids. The head capsule contains voluminous glands whose appeasement secretions are crucial for the beetle survival in ant colonies. The brain, in turn, has been shifted into the neck region. The prepharyngeal dilator is composed of an entire series of bundles. However, the pharynx does not show any peculiar adaptations to taking up liquid food. We demonstrate that far-reaching cephalic modifications characterize C. testaceus, and that the development of appeasement glands and adaptation of the mouthparts to trophallaxis determine the head architecture of this extreme myrmecophile.