A Taxonomic Revision of the South American Trilobite Cockroaches of Parahormetica Brunner von Wattenwyl 1865 (Blattodea: Blaberidae), with Description of Parahormetica museunacional sp. nov. from the Atlantic Forest.

The taxonomically intricate genus of trilobite cockroaches, Parahormetica Brunner von Wattenwyl, 1865, is revised based on a comparative morphological analysis. The goals of this study are to review the nomenclature, propose hypotheses about specific delimitation, and provide diagnoses to allow identification of the taxonomic units in the genus. Based on the revised status of Parahormetica, we transferred Parahormetica hylaeceps Miranda-Ribeiro, 1936, and Parahormetica punctata Saussure, 1873, to the genus Bionoblatta Rehn, 1940. Therefore, the genus includes now four species of giant cockroaches which are predominantly distributed on the Atlantic Forest: Parahormetica bilobata (Saussure, 1864), Parahormetica cicatricosa Saussure, 1869, Parahormetica monticollis (Burmeister, 1838), and Parahormetica museunacional sp. nov. (holotype male deposited in DZUP: Brazil, Paraná). Diagnoses, key, distribution maps, images of living, non-type, and type specimens are made available. Our results make clear that the status and limits among Brachycolini genera pending a full revision.

Propelling and perturbing appendages together facilitate strenuous ground self-righting.

Terrestrial animals must self-right when overturned on the ground, but this locomotor task is strenuous. To do so, the discoid cockroach often pushes its wings against the ground to begin a somersault which rarely succeeds. As it repeatedly attempts this, the animal probabilistically rolls to the side to self-right. During winged self-righting, the animal flails its legs vigorously. Here, we studied whether wing opening and leg flailing together facilitate strenuous ground self-righting. Adding mass to increase hind leg flailing kinetic energy increased the animal's self-righting probability. We then developed a robot with similar strenuous self-righting behavior and used it as a physical model for systematic experiments. The robot's self-righting probability increased with wing opening and leg flailing amplitudes. A potential energy landscape model revealed that, although wing opening did not generate sufficient kinetic energy to overcome the high pitch potential energy barrier to somersault, it reduced the barrier for rolling, facilitating the small kinetic energy from leg flailing to probabilistically overcome it to self-right. The model also revealed that the stereotyped body motion during self-righting emerged from physical interaction of the body and appendages with the ground. Our work demonstrated the usefulness of potential energy landscape for modeling self-righting transitions.

Two New Species of the Genus Eucorydia (Blattodea: Corydiidae) from the Nansei Islands in Southwest Japan.

Two new species of the cockroach genus Eucorydia Hebard, 1929 from the Nansei Islands in Southwest Japan were compared to two closely related congeners, Eucorydia yasumatsui Asahina, 1971 and Eucorydia dasytoides (Walker, 1868). Eucorydia donanensis Yanagisawa, Sakamaki, and Shimano sp. nov. from Yonaguni-jima Island was characterized by an overall length of 12.5-14.5 mm in males. The dorsal side of the male abdomen was entirely dark purple and there was an obscure orange band running down the middle of the tegmen. Eucorydia tokaraensis Yanagisawa, Sakamaki, and Shimano sp. nov. was characterized by an overall length of 12.0-13.0 mm in males and a distinct orange band running down the middle of the tegmen. Eucorydia yasumatsui, E. donanensis, E. tokaraensis and the zonata population of E. dasytoides were divided into four lineages in a maximum-likelihood tree generated from a dataset concatenated from five (two nuclear, 28S rRNA, histone H3, and three mitochondrial, COII, 12S rRNA, 16S rRNA) genes. We recognized the three Japanese lineages E. yasumatsui, E. donanensis, and E. tokaraensis as distinct species, which were also supported by the pairwise genetic distances (5.4-7.8%, K2P) of the COI sequences. Morphometric analysis was performed on the genitalia. A principal component analysis plot revealed that the sizes of the genitalia in the three Japanese species were similar to each other and smaller than that of the zonata population of E. dasytoides. The analysis also revealed that the three Japanese species were distinguished from each other by combinations of the sizes of L3 and L7 sclerites and the shape of R2 sclerite, with some overlapping exceptions.

Comparative study with scanning electron microscopy on the antennal sensilla of two main castes of Coptotermes formosanus Shiraki (Blattaria:Rhinotermitidae).

Sensilla on antennae of the workers and soldiers of Coptotermes formosanus Shiraki were examined by scanning electron microscopy in this study. As the two castes were allocated totally different tasks in the termite colony, we wondered if there was a big difference between their antennae which were recognized as the main sensory appendages of insects. Therefore, detailed information about the morphology, distribution and abundance of various types of sensilla was described in this report. However, our results showed no obvious caste dimorphism was observed. The morphology of antennae and sensilla as well as the general sensilla distribution pattern did not differ between the workers and soldiers of C. formosanus. In total, seven types of sensilla including sensilla chaetica (I, II, III), Böhm bristles, sensilla campaniformia (I, II, III), sensilla trichodea, sensilla basiconica, sensilla trichodea curvata and sensilla capitula were found on the antennae. Additionally, small apertures were found scattered randomly in the antennal cuticle. Functions of these sensilla or structures were proposed to be mechanoreceptors, chemo-receptors, thermo-hygroreceptors, co2-receptors etc. which probably play crucial roles in their various social behaviors.

New Cockroaches (Dictyoptera: Blattodea) from French Guiana and a Revised Checklist for the Region.

Although French Guiana is one of the greatest hotspots of cockroach biodiversity on Earth, there are still undocumented species. From both newly collected and museum specimens, we provide species descriptions for Buboblatta vlasaki sp. nov., Lamproblatta antoni sp. nov., and Euhypnorna bifuscina sp. nov. and report new geographic records for species in the genera Epilampra Burmeister, Euphyllodromia Shelford, Ischnoptera Burmeister, and Euhypnorna Hebard. Finally, we update the checklist of species known from the region to 163 total species records from French Guiana, making it the second greatest hotspot of known cockroach biodiversity on Earth.

Scaling of claw sharpness: mechanical constraints reduce attachment performance in larger insects.

Claws are the most widespread attachment devices in animals, but comparatively little is known about the mechanics of claw attachment. A key morphological parameter in determining attachment ability is claw sharpness; however, there is a conflict between sharpness and fracture resistance. Sharper claws can interlock on more surfaces but are more likely to break. Body size interacts with this conflict such that larger animals should have much blunter claws and consequently poorer attachment ability than smaller animals. This expected size-induced reduction in attachment performance has not previously been investigated, and it is unclear how animals deal with this effect, and whether it indeed exists. We explored the scaling of claw sharpness with body size using four insect species (Nauphoeta cinerea, Gromphadorhina portentosa, Atta cephalotes and Carausius morosus) each covering a large size range. The scaling of claw sharpness varied significantly between species, suggesting that they face different pressures regarding claw function. Attachment forces were measured for A. cephalotes and G. portentosa (which had different scaling of claw sharpness) on several rough surfaces using a centrifuge setup. As expected, attachment performance was poorer in larger animals. Firstly, larger animals were more likely to slip, although this effect depended on the scaling of claw sharpness. Secondly, when they gripped, they attached with smaller forces relative to their weight. This size-induced reduction in attachment performance has significant implications for the attachment ability of larger animals on rough surfaces.

The cephalo-thoracic apparatus of Caputoraptor elegans may have been used to squeeze prey.

Alienoptera is an insect order recently described from mid-Cretaceous amber [1] and is phylogenetically nested in the Dictyoptera lineage. Alienoptera currently comprises three species: Alienopterus brachyelytrus[1], Alienopterella stigmatica[2] and Caputoraptor elegans[3]. The most interesting is Caputoraptor elegans, which was recently described in Current Biology by Bai and colleagues [3] and which has an unusual cephalo-thoracic device formed by wing-like extensions of the genae and the corresponding edges of the pronotum. Bai and colleagues [3] suggested that the cephalo-thoracic apparatus may have been used to hold the female and male together during copulation. According to this possible function, the cephalo-thoracic apparatus of the female would fit together with the spread forewings of the male while the female was on the back of the male during copulation. This function was proposed based on examination of females and nymphs, and the authors stated that it could be falsified if a male with a similar apparatus were discovered. After examining a male nymph of this species (Figure 1), I here suggest that the cephalo-thoracic apparatus was not used for copulation but was instead used for predation and feeding.

Body-terrain interaction affects large bump traversal of insects and legged robots.

Small animals and robots must often rapidly traverse large bump-like obstacles when moving through complex 3D terrains, during which, in addition to leg-ground contact, their body inevitably comes into physical contact with the obstacles. However, we know little about the performance limits of large bump traversal and how body-terrain interaction affects traversal. To address these, we challenged the discoid cockroach and an open-loop six-legged robot to dynamically run into a large bump of varying height to discover the maximal traversal performance, and studied how locomotor modes and traversal performance are affected by body-terrain interaction. Remarkably, during rapid running, both the animal and the robot were capable of dynamically traversing a bump much higher than its hip height (up to 4 times the hip height for the animal and 3 times for the robot, respectively) at traversal speeds typical of running, with decreasing traversal probability with increasing bump height. A stability analysis using a novel locomotion energy landscape model explained why traversal was more likely when the animal or robot approached the bump with a low initial body yaw and a high initial body pitch, and why deflection was more likely otherwise. Inspired by these principles, we demonstrated a novel control strategy of active body pitching that increased the robot's maximal traversable bump height by 75%. Our study is a major step in establishing the framework of locomotion energy landscapes to understand locomotion in complex 3D terrains.

Dynamic traversal of large gaps by insects and legged robots reveals a template.

It is well known that animals can use neural and sensory feedback via vision, tactile sensing, and echolocation to negotiate obstacles. Similarly, most robots use deliberate or reactive planning to avoid obstacles, which relies on prior knowledge or high-fidelity sensing of the environment. However, during dynamic locomotion in complex, novel, 3D terrains, such as a forest floor and building rubble, sensing and planning suffer bandwidth limitation and large noise and are sometimes even impossible. Here, we study rapid locomotion over a large gap-a simple, ubiquitous obstacle-to begin to discover the general principles of the dynamic traversal of large 3D obstacles. We challenged the discoid cockroach and an open-loop six-legged robot to traverse a large gap of varying length. Both the animal and the robot could dynamically traverse a gap as large as one body length by bridging the gap with its head, but traversal probability decreased with gap length. Based on these observations, we developed a template that accurately captured body dynamics and quantitatively predicted traversal performance. Our template revealed that a high approach speed, initial body pitch, and initial body pitch angular velocity facilitated dynamic traversal, and successfully predicted a new strategy for using body pitch control that increased the robot's maximal traversal gap length by 50%. Our study established the first template of dynamic locomotion beyond planar surfaces, and is an important step in expanding terradynamics into complex 3D terrains.

The role of ocelli in cockroach optomotor performance.

Insect ocelli are relatively simple eyes that have been assigned various functions not related to pictorial vision. In some species they function as sensors of ambient light intensity, from which information is relayed to various parts of the nervous system, e.g., for the control of circadian rhythms. In this work we have investigated the possibility that the ocellar light stimulation changes the properties of the optomotor performance of the cockroach Periplaneta americana. We used a virtual reality environment where a panoramic moving image is presented to the cockroach while its movements are recorded with a trackball. Previously we have shown that the optomotor reaction of the cockroach persists down to the intensity of moonless night sky, equivalent to less than 0.1 photons/s being absorbed by each compound eye photoreceptor. By occluding the compound eyes, the ocelli, or both, we show that the ocellar stimulation can change the intensity dependence of the optomotor reaction, indicating involvement of the ocellar visual system in the information processing of movement. We also measured the cuticular transmission, which, although relatively large, is unlikely to contribute profoundly to ocellar function, but may be significant in determining the mean activity level of completely blinded cockroaches.

Morphology and ultrastructure of the tarsal adhesive organs of the Madagascar hissing cockroach Gromphadorhina portentosa.

The present transmission and scanning electron microscopic study of the ultramorphology of the pliable attachment pads (arolium, euplantulae) of the Madagascar hissing cockroach Gromphadorhina portentosa reveals structural evidence for their function in producing, storing, and secreting an adhesion-mediating secretion and releasing it to the exterior. The exocrine epidermal tissue of both the arolium and the euplantula is significantly enlarged by numerous invaginations stretching into the hemolymph cavity. Its cells show large nuclei, numerous mitochondria, Golgi complexes, and a prominent rough-surfaced endoplasmic reticulum integrated within an electron-dense cytoplasm that contains numerous vesicles of diverse electron density and size. Invaginations of the cell membrane provide evidence for strong membrane turnover. The glandular epithelium of both the arolium and the euplantula releases the adhesion-mediating secretion into a subcuticular void from which it has to permeate the thick cuticle of the adhesive pads. The subcuticular void is compartmentalized by cuticle bands through which the adhesion-mediating secretion permeates via small canals. The secretion subsequently enters a larger storage reservoir before being received by a prominent sponge-like cuticle. The structural differences between the arolium and the euplantula consist of the number and length of the interdigitations spanning the hemolymph cavity, of the subdivision of the subcuticular reservoir by cuticle bands, and of the thickness of the sponge-like cuticle. The structural results are discussed with respect to the production of a chemically complex (emulsion-like) adhesive, its controlled release to the exterior, and the micromechanical properties of the cuticle of the pliable pad.

Embryonic development of Eucorydia yasumatsui Asahina, with special reference to external morphology (Insecta: Blattodea, Corydiidae).

As the first step in the comparative embryological study of Blattodea, with the aim of reconstructing the groundplan and phylogeny of Dictyoptera and Polyneoptera, the embryonic development of a corydiid was examined and described in detail using Eucorydia yasumatsui. Ten to fifteen micropyles are localized on the ventral side of the egg, and aggregated symbiont bacterial "mycetomes" are found in the egg. The embryo is formed by the fusion of paired blastodermal regions, with higher cellular density on the ventral side of the egg. This type of embryo formation, regarded as one of the embryological autapomorphies of Polyneoptera, was first demonstrated for "Blattaria" in the present study. The embryo undergoes embryogenesis of the short germ band type, and elongates to its full length on the ventral side of the egg. The embryo undergoes katatrepsis and dorsal closure, and then finally, it acquires its definitive form, keeping its original position on the ventral side of the egg, with its anteroposterior axis never reversed throughout development. The information obtained was compared with that of previous studies on other insects. "Micropyles grouped on the ventral side of the egg" is thought to be a part of the groundplan of Dictyoptera, and "possession of bacteria in the form of mycetomes" to be an apomorphic groundplan of Blattodea. Corydiid embryos were revealed to perform blastokinesis of the "non-reversion type (N)", as reported in blaberoid cockroaches other than Corydiidae ("Ectobiidae," Blaberidae, etc.) and in Mantodea; the embryos of blattoid cockroaches (Blattidae and Cryptocercidae) and Isoptera undergo blastokinesis of the "reversion type (R)," in which the anteroposterior axis of the embryo is reversed during blastokinesis. Dictyopteran blastokinesis types can be summarized as "Mantodea (N) + Blattodea [= Blaberoidea (N) + Blattoidea (R) + Isoptera (R)]".

Not flying blind: a comparative study of photoreceptor function in flying and non-flying cockroaches.

Flying is often associated with superior visual performance, as good vision is crucial for detection and implementation of rapid visually guided aerial movements. To understand the evolution of insect visual systems it is therefore important to compare phylogenetically related species with different investments in flight capability. Here, we describe and compare morphological and electrophysiological properties of photoreceptors from the habitually flying green cockroach Panchlora nivea and the American cockroach Periplaneta americana, which flies only at high ambient temperatures. In contrast to Periplaneta, ommatidia in Panchlora were characterized by two-tiered rhabdom, which might facilitate detection of polarized light while flying in the dark. In patch-clamp experiments, we assessed the absolute sensitivity to light, elementary and macroscopic light-activated current and voltage responses, voltage-activated potassium (Kv) conductances, and information transfer. Both species are nocturnal, and their photoreceptors were similarly sensitive to light. However, a number of important differences were found, including the presence in Panchlora of a prominent transient Kv current and a generally low variability in photoreceptor properties. The maximal information rate in Panchlora was one-third higher than in Periplaneta, owing to a substantially higher gain and membrane corner frequency. The differences in performance could not be completely explained by dissimilarities in the light-activated or Kv conductances; instead, we suggest that the superior performance of Panchlora photoreceptors mainly originates from better synchronization of elementary responses. These findings raise the issue of whether the evolutionary tuning of photoreceptor properties to visual demands proceeded differently in Blattodea than in Diptera.

A simple and quick method of displaying liquid-preserved morphological structures for microphotography.

Stabilising microstructures and small organisms for microphotography can be frustrating. If it is desired to take photographs in water from structures just cleared in potassium hydroxide, some sort of stabilisation is necessary otherwise the structures drift. Similarly, specimens taken from glycerol or alcohol, or those placed in alcohol, drift even more as the alcohol evaporates. Bits of crushed coverslip, glass beads, micro pins and dobs of Vaseline® have all been used to help keep the structures in place. In an attempt to solve the problem of "drifting genitalia" a simple solution was inadvertently discovered. A method used for whole insects by Sam Droege and his colleagues of the United States Geological Survey (Droege 2016; USGS Bee Inventory and Monitoring Lab 2016) was adapted for use with insect genitalia.

Origin of origami cockroach reveals long-lasting (11 Ma) phenotype instability following viviparity.

Viviparity evolved in bacteria, plants, ˃141 vertebrate lineages (ichthyosaurs, lizards, fishes, mammals, and others), and in 11 of 44 insect orders. Live-birth cockroaches preserved with brood sac (3D recovered two times optically) included Diploptera vladimir, Diploptera savba, Diploptera gemini spp.n., D. sp.1-2, and Stegoblatta irmgardgroehni from Green River, Colorado; Quilchena, Republic; McAbee, Canada; and Baltic amber, Russia (49, 54, and 45 Ma). They evolved from rare and newly evolved Blaberidae; they radiated circumtropically, later expanded into SE Asia, and have now spread to Hawaii and the SE USA. Association of autapomorphic characters that allow for passive and active protections from parasitic insects (unique wing origami pleating identical with its egg case-attacking wasp) suggest a response to high parasitic loads. Synchronized with global reorganization of the biota, morphotype destabilization in roaches lasted approximately 11-22 Ma, including both the adaptation of novel characters and the reduction of others. Thus, while viviparity can be disadvantageous, in association with new Bauplans and/or behaviors, it can contribute to the evolution of taxa with viviparous representatives that are slightly selectively preferred.

Biomechanical Factors in the Adaptations of Insect Tibia Cuticle.

Insects are among the most diverse groups of animals on Earth. Their cuticle exoskeletons vary greatly in terms of size and shape, and are subjected to different applied forces during daily activities. We investigated the biomechanics of the tibiae of three different insect species: the desert locust (Schistocerca gregaria), American cockroach (Periplaneta americana) and Death's Head cockroach (Blaberus discoidalis). In a previous work, we showed that these tibiae vary not only in geometry (length, radius and thickness) but also in material quality (Young's modulus) and in the applied stress required to cause failure when loaded in bending. In the present work we used kinematic data from the literature to estimate the forces and stresses arising in vivo for various different activities, and thus calculated factors of safety defined as the ratio between the failure stress and the in vivo stress, adjusting the failure stress to a lower value to allow for fatigue failure in the case of frequently repeated activities. Factors of safety were found to vary considerably, being as little as 1.7 for the most strenuous activities, such as jumping or escaping from tight spaces. Our results show that these limbs have evolved to the point where they are close to optimal, and that instantaneous failure during high-stress activities is more critical than long-term fatigue failure. This work contributes to the discussion on how form and material properties have evolved in response to the mechanical functions of the same body part in different insects.

New cockroach species of the genus Panchlora Burmeister (Blaberidae, Panchlorinae) from Ecuador.

The genus Panchlora includes 49 species, but only 45 are widely distributed in Central and South America. Most of them are green. The new species herein described presents an ornamental coloration markedly different of all until now described species. Panchlora kozaneki sp. n. is similar to Panchlora pulchella Burmeister, 1838. The number of species known from Ecuador is increased to eight.

The neuropeptide SIFamide in the brain of three cockroach species.

The sequence as well as the distribution pattern of SIFamide in the brain of different insects is highly conserved. As a general rule, at least four prominent SIFamide-immunoreactive somata occur in the pars intercerebralis. They arborize throughout the brain and the ventral nerve cord. Whereas SIFamide is implicated in mating and sleep regulation in Drosophila, other functions of this peptide remain largely unknown. To determine whether SIFamide plays a role in the circadian system of cockroaches, we studied SIFamide in Rhyparobia (= Leucophaea) maderae (Blaberidae), Periplaneta americana (Blattidae), and Therea petiveriana (Polyphagidae). Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry revealed identical SIFamide sequences (TYRKPPFNGSIFamide) in the three species. In addition to four large immunoreactive cells in the pars intercerebralis (group 1), smaller SIFamide-immunoreactive somata were detected in the pars intercerebralis (group 2), in the superior median protocerebrum (group 3), and in the lateral protocerebrum (group 4). Additional cells in the optic lobe (group 5) and posterior protocerebrum (group 6) were stained only in P. americana. Almost the entire protocerebrum was filled with a beaded network of SIFamide-immunoreactive processes that especially strongly invaded the upper unit of the central body. Double-label experiments did not confirm colocalizations with γ-aminobutyric acid (GABA) or the circadian coupling peptide pigment-dispersing factor (PDF). In contrast to locusts, colocalization of SIFamide and histamine immunoreactivity occurred not in group 1, but in group 4 cells. Because the accessory medulla displayed SIFamide immunoreactivity and injections of SIFamide delayed locomotor activity rhythms circadian time-dependently, SIFamide plays a role in the circadian system of cockroaches. J. Comp. Neurol. 524:1337-1360, 2016. © 2015 Wiley Periodicals, Inc.

The Optic Lobes Regulate Circadian Rhythms of Olfactory Learning and Memory in the Cockroach.

The cockroach, Leucophaea maderae, can be trained in an associative olfactory memory task by either classical or operant conditioning. When trained by classical conditioning, memory formation is regulated by a circadian clock, but once the memory is formed, it can be recalled at any circadian time. In contrast, when trained via operant conditioning, animals can learn the task at any circadian phase, but the ability to recall the long-term memory is tied to the phase of training. The optic lobes of the cockroach contain a circadian clock that drives circadian rhythms of locomotor activity, mating behavior, sensitivity of the compound eye to light, and the sensitivity of olfactory receptors in the antennae. To evaluate the role of the optic lobes in regulating learning and memory processes, the authors examined the effects of surgical ablation of the optic lobes on memory formation in classical conditioning and memory recall following operant conditioning. The effect of optic lobe ablation was to "rescue" the deficit in memory acquisition at a time the animals normally cannot learn and "rescue" the animal's ability to recall a memory formed by operant conditioning at a phase where memory was not normally expressed. The results suggested that the optic lobe pacemaker regulates these processes through inhibition at "inappropriate" times of day. As a pharmacological test of this hypothesis, the authors showed that injections of fipronil, an antagonist of GABA and glutamate-activated chloride channels, had the same effects as optic lobe ablation on memory formation and recall. The data suggest that the optic lobes contain the circadian clock(s) that regulate learning and memory processes via inhibition of neural processes in the brain.