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On the evolution of raptorial legs—An insect example (Hemiptera: Reduviidae: Phymatinae)
Abstract
The presence of chelate and subchelate fore legs in Phymatinae (Hemiptera: Reduviidae), or ambush bugs, provides a unique opportunity to study the evolution of different types of raptorial legs in a closely related group of arthropods. Themonocorini have simple, possibly raptorial legs, Phymatini and Macrocephalini distinct subchelate fore legs, and the charismatic Carcinocorini are the only insects with a chelate fore leg apart from female dryinid Chysidoidea (Hymenoptera). Relationships between the four phymatine tribes are here analyzed in a cladistic framework thus permitting testable hypotheses on the evolution of raptorial legs. The presented analysis of phymatine tribal level relationships is based on a dataset comprising 11 species of Phymatinae and 54 non-phymatine Reduviidae and Heteroptera. The molecular data set consists of ∼3500 MAFFT aligned bases of 16S, 28S D2–D3, and 18S ribosomal genes. Parsimony and maximum likelihood analyses resulted in identical topologies for the ingroup with the relationships Themonocorini + (Phymatini + (Carcinocorini + Macrocephalini)) receiving high support values. Eleven morphological characters, eight of them derived from fore leg morphology, were optimized on the parsimony analysis. These optimizations indicate that the ancestral ambush bug had a simple raptorial leg; that size reduction of the tarsus, enlargement of the femur, curvature of the fore tibia, armature of tibia and femur with rows of tiny tubercles that allow for gripping of a prey insect, and the large process on the ventral surface of the femur arose in the common ancestor of Carcinocorini + Macrocephalini + Phymatini. The chelate leg in Carcinocorini is likely derived from a subchelate precursor similar to the one seen in recent Macrocephalini and may have evolved through elongation of the ventral, proximal portion of the fore femur and modification of the median process to form part of the digitus fixus.
© The Willi Hennig Society 2010.
... Here, another example for this multifunctionality is presented, the raptorial forelegs. These prehensile legs are used for prey capturing and can most commonly be divided into two different types within insects: chelate and subchelate raptorial forelegs legs (compare Fig. 1 in Weirauch et al. 2011). The chelate type-best known as 'crab claws'-is in insects present in some Reduviidae (Hemiptera; Weirauch et al. 2011). ...
... These prehensile legs are used for prey capturing and can most commonly be divided into two different types within insects: chelate and subchelate raptorial forelegs legs (compare Fig. 1 in Weirauch et al. 2011). The chelate type-best known as 'crab claws'-is in insects present in some Reduviidae (Hemiptera; Weirauch et al. 2011). The sub-chelate type raptorial forelegs are best known for Mantodea (see Roy 1999;Wieland 2013or Brannoch et al. 2017. ...
... Different setups of spines on the sub-chelate type raptorial forelegs are also present in the hemipteran group Reduviidae (Weirauch et al. 2011;Zhang et al. 2016;Castro-Huertas et al. 2019), including enlarged spines that might resemble the here, and in mantises (Loxton and Nicholls 1979), described system. ...
The insect leg is a multifunctional device, varying tremendously in form and function within Insecta: from a common walking leg, to burrowing, swimming or jumping devices, up to spinning apparatuses or tools for prey capturing. Raptorial forelegs, as predatory striking and grasping devices, represent a prominent example for convergent evolution within insects showing strong morphological and behavioural adaptations for a lifestyle as an ambush predator. However, apart from praying mantises (Mantodea)—the most prominent example of this lifestyle—the knowledge on morphology, anatomy, and the functionality of insect raptorial forelegs, in general, is scarce. Here, we show a detailed morphological description of raptorial forelegs of Mantispa styriaca (Neuroptera), including musculature and the material composition in their cuticle; further, we will discuss the mechanism of the predatory strike. We could confirm all 15 muscles previously described for mantis lacewings, regarding extrinsic and intrinsic musculature, expanding it for one important new muscle—M24c. Combining the information from all of our results, we were able to identify a possible catapult mechanism (latch-mediated spring actuation system) as a driving force of the predatory strike, never proposed for mantis lacewings before. Our results lead to a better understanding of the biomechanical aspects of the predatory strike in Mantispidae. This study further represents a starting point for a comprehensive biomechanical investigation of the convergently evolved raptorial forelegs in insects.
... Rédei and Tsai (2011) also noted a strong similarity in the phalli of male Holoptilinae and Centrocnemidinae (e.g., endosomal appendages not fully enclosed by the endosoma in these subfamilies, but fully enclosed in Phymatinae [Carayon et al., 1958;Davis, 1957]). Recent morphology-based or molecular hypotheses recovered either the ant-feeding specialist group Holoptilinae (Weirauch, 2008;Weirauch et al., 2011;Weirauch and Munro, 2009;Zhang et al., 2016) or Holoptilinae + the Oriental, tree-bark associated Centrocnemidinae (Hwang and Weirauch, 2012) as sister group to Phymatinae. The divergence of Phymatinae from other assassin bugs has been estimated to have occurred in the Cretaceous, approximately 114 mya, with diversification within the group starting around 66 mya (Hwang and Weirauch, 2012), making this subfamily distinctly older than the great majority of assassin bug subfamilies. ...
... These bugs are easily distinguished from other Reduviidae by their robust raptorial forelegs, fusiform distal flagellomeres, well developed bucculae, and disruptive color pattern (Weirauch et al., 2014). The monogeneric tribe Themonocorini (5 spp.) is confined to sub-Saharan Africa and members differ from other ambush bugs in possessing simple raptorial forelegs with long spines (Carayon et al., 1958;Weirauch et al., 2011). These small (4 mm) ambush bugs have been found in rotting masses of plant matter and nests of weaver birds, presumably stalking arthropod prey, but their natural history is otherwise unknown (van Doesburg and Jacobs, 2011). ...
... Surprisingly, given the charisma of ambush bugs, the monophyly of the four tribes has remained untested and relationships between the tribes have not been investigated, beyond the hypothesis proposed by Weirauch et al. (2011). That analysis, based on a sample of only 11 Phymatinae, but including representatives of the four tribes, recovered Themonocorini as sister to Carcinocorini + Macrocephalini and Phymatini; sampling of Macrocephalini was restricted to two Neotropical genera. ...
The ambush bugs (Heteroptera: Reduviidae: Phymatinae) are a diverse clade of predators known for their cryptic hunting behavior and morphologically diverse raptorial forelegs. Despite their striking appearance, role as pollinator predators, and intriguing biogeographic distribution, phylogenetic relationships within Phymatinae are largely unknown and the evolutionary history of the subfamily has remained in the dark. We here utilize the most extensive molecular phylogeny of ambush bugs to date, generated from a 3,328 base pair molecular dataset, to refine our understanding of phymatine relationships, estimate dates of divergence (BEAST 2), and uncover historical biogeographic patterns (S-DIVA and DEC). This taxon set (39 species of Phymatinae and six outgroups) allowed reevaluation of the proposed sister group of Phymatinae and tribal-level relationships within the group, and for the first time proposes species-level relationships within Phymata Latreille, the largest genus of ambush bugs (∼108 spp.). Available evidence suggests that Phymata originated in the Neotropical region, with subsequent dispersals to the Nearctic and Palearctic regions. This study provides a framework for future research investigating the evolutionary history of ambush bugs, as well as ecological and microevolutionary investigations.
... nov. Acquisitions of raptorial forelegs, a significant morphological innovation for the predatory insects, were independently evolved across multiple lineages, for example, praying mantis (Mantodea), mantid lacewings and their relatives (Neurotpera: Rhachiberothidae, Dipteromantispidae), ambush bugs (Hemiptera: Reduviidae: Emesinae, Phymatinae), dance flies (Diptera: Empididae: Hemerodromiinae), and shore flies (Diptera: Ephydridae: Ochthera) (Minakawa et al., 2007;Weirauch et al., 2011;Dittmann et al., 2015;Brannoch et al., 2017;Castro-Huertas et al., 2019;Lu et al., 2020;Bäumler et al., 2023). The raptorial forelegs are typically characterized by elongated coxa and highly modified femur or tibia, which collectively constitute main capture-andcontrol structures (New, 1991). ...
... For the typical raptorial foreleg, the expanded profemur harbored abundant muscles which forced a rapid closure of the protibiae against ventral surface of profemora (Parsons, 1968;Weirauch et al., 2011), and profemoral spines, modified protibia and protarsus coworked with femur in tightly capturing and controlling prey. It is clear that the conditions of profemur, protibia and protarsus of Archarhachiberotha did not adapt for a regular predation especially for capturing and controlling prey as the other mantispoids did. ...
During the Cretaceous period, the lacewing superfamily Mantispoidea, with an assemblage of species possessing raptorial forelegs, have undergone a rapid species radiation, characterized by abundant species richness and high morphological plasticity. Nevertheless, the morphology and early evolution of the specialized predatory organ around the time of its origin in raptorial Mantispoidea have been poorly documented due to the rarity of fossil evidence, especially for the pre‐Cretaceous fossils. Herein, a new genus and new species, that is Archarhachiberotha longitarsa Wang, Ren et Wang gen. et sp. nov., was described from the Middle Jurassic Jiulongshan Formation of northeastern China. This new genus was characterized by the remarkable raptorial forelegs, that is, typically elongated coxa, relatively less‐swollen femur and rudimentary small femoral spines, and well‐developed tarsi. Considering the peculiar morphological combination and antiquity of the new genus, it was assigned to be a stem‐group lineage of Mantispoidea. Also, the detailed analyses of morphology and biological functions of raptorial forelegs were made to conclude that the new genus evolved into an unknown but primitive raptorial type that was distinctly different from the extant morphological features and raptorial mechanisms. In addition, the evolutionary tendency of raptorial Mantispoidea herein summarized highlights morphological diversity and disparity between fossil and extant representatives, and provides a rare case to explore the entire evolutionary history of a specialized structure in one lineage.
... Apart from specialized predatory and hematophagous groups, Reduviidae also comprise large lineages of euryphagous predators, for example, many Harpactorinae (>2,800 spp.), the largest subfamily of Reduviidae (Maldonado, 1990;. Behavioural and morphological adaptations to prey capture are stunningly diverse across Reduvioidea and include sticky trap predation using plant resins, scavenging on sticky plants, ant-luring, diverse types of raptorial legs including legs that feature tibial attachment structures (fossula spongiosa) and legs with raptorial glands Weirauch, 2007;Weirauch et al., 2010Weirauch et al., , 2011Zhang & Weirauch, 2013;. Certain immature assassin bugs use camouflage as stealth and anti-predator defence, a strategy that has been dated to the Mid-Cretaceous (Wang et al., 2016), and morphological structures involved in camouflage are diverse across Reduvioidea (Jackson & Pollard, 2007;Weirauch, 2006). ...
... Taxonomic history: For much of the 19th and 20th centuries, Phymatinae, the ambush bugs, were treated as a distinct family (Phymatidae) (Froeschner & Kormilev, 1989;Handlirsch, 1897;Kormilev, 1962). Their placement within Reduviidae was convincingly argued by Carayon et al. (1958), who reduced the group to its current One important exception is the position of Themonocoris that in the current study is not recovered as sister taxon to all remaining Phymatinae as found in previous analyses (Masonick et al., 2017;Weirauch et al., 2011), but nested within the subfamily (sister to 'Macrocephalini' + Carcinocorini). All ambush bugs except Themonocoris have highly modified forelegs and the subchelate legs in Phymatinae and 'Macrocephalini' are thought to be homologous. ...
Assassin bugs (Hemiptera: Reduviidae Latreille) comprise not only one of the largest radiations of predatory animals (22 subfamilies; >6,800 spp.) but also include the medically important kissing bugs (Triatominae Jeannel). Reduviidae are morphologically diverse, engage in an astounding array of predatory strategies and have evolved some of the most unique anti-predator and stealth techniques in the animal kingdom. While significant progress has been made to reveal the evolutionary history of assassin bugs and revise their taxonomy, the non-monophyly of the second largest assassin bug subfamily, Reduviinae Latreille, remains to be addressed. Leveraging phylogenomic data (2,291 loci) and 112 morphological characters, we performed the first data-and taxon-rich (195 reduvioid taxa) combined phylogenetic analysis across Reduvioidea and reconstructed morphological diagnostic features for major lineages. We corroborated the rampant polyphyly of Reduviinae that demands substantial revisions to the subfamilial and tribal classification of assassin bugs. Our new classification for Reduviidae reduces the number of subfamilies to 19 and recognizes 40 tribes. We describe three new subfam-ilies to accommodate distantly related taxa previously classified as Reduviinae (Heteropinae subfam. nov., Nanokeralinae subfam. nov., and Pasirinae subfam. nov.). Triatominae sensu nov. are expanded to include closely related predatory reduviine
... The structures of the fore legs of most assassin bugs, as predators, are designed for capturing of prey. The functional morphological plasticity of fore leg in Reduviidae has been discussed by some authors (Miller 1942;Cai & Tomokuni 2003;Weirauch et al. 2011;Zhang & Weirauch 2013). The morphological diversity of the reduviid fore-leg apparently reflects their predatory habits and methods of different groups of the family Reduviidae. ...
... The morphological diversity of the reduviid fore-leg apparently reflects their predatory habits and methods of different groups of the family Reduviidae. The fore legs of Phymatinae and Emesinae may become extremely specialized and resemble to those of crab and mantis (Wygodzinsky 1966;Weirauch et al. 2011). The fore leg of many assassin bugs is armed with the special structure, such as fossula spongiosa (Salyavatinae, Triatominae, Peiratinae, Ectrichodinae, Reduviinae), spines, teeth, dense setae, or clothed with exogenous sticky substance (plant resins and gums) (Ectinoderini, Apiomerini and Diaspidiini) (Miller 1942;Davis 1969), endogenous sticky substances produced by sticky glands (Zhang & Weirauch 2013), and so on, in order to increase the capacity for catching the preys. ...
Flexitibia, a new genus, in the division Euagorasaria of the assassin bug subfamily Harpactorinae from Yunnan Province of China is described. The type species, Flexitibia orientalis sp. nov., is described and illustrated. A key to the closely related genera is provided. The type specimens are kept in the Entomological Museum of China Agricultural University, Beijing.
... The rapid movement and long-distance reach of the forelegs are leveraged by elongation of the forecoxa (New, 1991). In some phymatine Reduviidae of the Hemiptera, the femur is extremely robust and the basitarsus is elongate and stout, providing strength to the reach of the lever-arm and hence power for grasping prey (Weirauch et al., 2011). In some mantises and mantid lacewings, one major spine is elongate and located on the inner surface of the forefemur, where it is positioned at a point along the distance from the base to a midpoint. ...
The Mantispidae (Neuroptera), commonly known as mantid lacewings or mantispids, are characterized by raptorial forelegs used by adults for predation. They have a fossil history extending to the Early Jurassic. During the past 180 Myr, the lineage has undergone significant evolutionary transformation, exhibiting an elevated diversity in morphology yet retaining the same overall ground plan. Although raptorial foreleg morphology and capture behaviour are well documented in extant insects, they are poorly known for premodern lineages, attributable to the scarcity and poor preservation of fossils. Here, we report two new genera and species of Mantispidae from mid-Cretaceous Myanmar (Burmese) amber. Both taxa have highly specialized raptorial forelegs and highlight modification of capture strategy in Cretaceous Mantispidae. The foreleg of both species has one major spine that is the same length as the foretibia on the ventral surface of the forefemur, which faces the foretibia with a row of robust setae. The two new amber mantid lacewings provide structural and functional indications that represent an extinct mode of capture strategy. The new findings reveal the presence of a geochronologically rapid diversification of Mantispidae during the Early Cretaceous, thereby illuminating the varied morphologies involved in prey-capture strategies integral to the early evolution of mantispids.
... The spines or setae of the profemur allow the predator to sense prey movement and ensnare victims [20]. Many insects possess raptorial forelegs to enhance their predation efficiency, such as ambush bugs (Hemiptera: Reduviidae: Emesinae, Phymatinae), shore flies of the genus Ochthera (Diptera: Ephydridae), ancient predatory roach-like insects and praying mantises (Dictyoptera), and mantidflies and their relatives (Neuroptera: Mantispidae, Rhachiberothidae, Dipteromantispidae) [3,19,[21][22][23][24]. However, the size and arrangement of profemoral spines or setae vary among these groups. ...
Mantidflies (Mantispidae) are an unusual and charismatic group of predatory lacewings (Neuroptera), whereby the adults represent a remarkable case of morphological and functional convergence with praying mantises (Mantodea). The evolutionary history of mantidflies remains largely unknown due to a scarcity of fossils. Here, we report the discovery of a highly diverse palaeofauna of mantidflies from the mid-Cretaceous (lowermost Cenomanian) of Myanmar. The raptorial forelegs of these mantidflies possess highly divergent morphological modifications, some of which are unknown among modern mantidflies, e.g. the presence of forked basal profemoral spines or even the complete loss of foreleg spine-like structures. A phylogenetic analysis of Mantispidae reveals a pattern of raptorial foreleg evolution across the family. The high species diversity and disparate foreleg characters might have been driven by diverse niches of predator–prey interplay in the complex tropical forest ecosystem of the mid-Cretaceous.
... Insects use different parts of their body to cling to mating partners, to catch prey, or to defend themselves, in most cases the mouthparts or the legs. However, in 400 million years of evolution [1,2], specialized devices were independently acquired in several groups to adopt these tasks, as for instance modified legs in mantids, assassin bugs or stick insects [3][4][5], or clasping antennae of the globular springtails [6]. So far, no known species used the neck region between the head and thorax in one of these functional contexts. ...
... The versatility of forms enabled arthropods to explore a wide variety of not only feeding behaviours but of general habits (Triplehorn and Johnson 2005). The morphological diversity includes: raptorial and saltatorial legs that enable, respectively, prey capturing and escape behaviours (Burrows and Morris 2003;Weirauch et al. 2011), the elongation of antenna in insects (e.g., Cerambycidae, Snodgrass 1935) or arachnid legs with an increase in the number of sensory structures (Willemart et al. 2009;Santer and Hebets 2011), flattened legs with varied functions such as swimming (Lyman 1943;Hartnoll 1971), excavation (Keltner and McCafferty 1986), food transport (Wille 1979) and intra-specific fights (Miyatake 1997). ...
Pedipalps in laniatorid harvestmen are usually cylindrical and raptorial, but species in Cosmetidae are exceptional in that adults, but not immature, have pedipalps flattened as a spoon. These have never been addressed with a functional approach. We have investigated possible roles of the pedipalps in Cosmetidae in exploration, social interactions and defence. Concerning exploration, we would expect the individuals to tap the substrate with the pedipalps, as species in the suborders Eupnoi and Dyspnoi do, but this was not observed. In social interactions, pedipalps could be used for holding females during mating or to fight other males but we could not relate the spoon-shape with any of the behaviours observed. For defence, we hypothesised that the pedipalp of adults would act as a barrier preventing the potentially noxious secretion from contacting the mouth when the individual performs 'leg-dabbing'. This is typical in adult cosmetids but not in other laniatorids. Because immature cosmetids have cylindrical pedipalps, we predicted that they would not perform 'leg-dabbing'. However, immature also performed leg-dabbing and the secretion did contact the mouth. We also found no evidence of pedipalps being used for digging, drinking or self-grooming. Although we have made progress, the question remains open.
... Phylogenetic tree was constructed by maximum-likelihood (ML) method (Figure 1). This phylogenetic analysis confirms the monophyly of Phymatinae, which is congruent with previous hypotheses (Weirauch et al. 2011;Masonick et al. 2017). The sister relationship between A. gestroi and Carcinocoris binghami is highly supported, this result may imply the close relationship of Macrocephalini and Carcinocorini. ...
The mitochondrial genome (mitogenome) of Amblythyreus gestroi is described in the present paper. The complete mitogenome is a 15,228 bp circular DNA molecule, containing 13 protein-coding genes, 22 tRNA genes, two rRNA genes and a control region. Genome organization, nucleotide composition and codon usage of the mitogenome are noted, secondary structures of all tRNAs are predicted. The monophyly of Phymatinae is highly supported by the phylogenetic tree. Phylogenetic implications of the A. gestroi mitogenome is briefly discussed.
... Various lineages of reduviids subsequently evolved alternate methods for holding on to prey [102]. For example, in a group of harpactorine Reduviidae that includes the large and widespread genus Zelus (leafhopper bugs), bioadhesives are secreted from glands on the fore-and mid-legs [103,104] [107,108]. In venomous groups such as scorpions, coevolution of venoms and grasping forelegs (pincers) has occurred such that the two systems are complementary [109]. ...
Heteropteran insects such as assassin bugs (Reduviidae) and giant water bugs (Belostomatidae) descended from a common predaceous and venomous ancestor, and the majority of extant heteropterans retain this trophic strategy. Some heteropterans have transitioned to feeding on vertebrate blood (such as the kissing bugs, Triatominae; and bed bugs, Cimicidae) while others have reverted to feeding on plants (most Pentatomomorpha). However, with the exception of saliva used by kissing bugs to facilitate blood-feeding, little is known about heteropteran venoms compared to the venoms of spiders, scorpions and snakes. One obstacle to the characterization of heteropteran venom toxins is the structure and function of the venom/labial glands, which are both morphologically complex and perform multiple biological roles (defense, prey capture, and extra-oral digestion). In this article, we describe three methods we have successfully used to collect heteropteran venoms. First, we present electrostimulation as a convenient way to collect venom that is often lethal when injected into prey animals, and which obviates contamination by glandular tissue. Second, we show that gentle harassment of animals is sufficient to produce venom extrusion from the proboscis and/or venom spitting in some groups of heteropterans. Third, we describe methods to harvest venom toxins by dissection of anaesthetized animals to obtain the venom glands. This method is complementary to other methods, as it may allow harvesting of toxins from taxa in which electrostimulation and harassment are ineffective. These protocols will enable researchers to harvest toxins from heteropteran insects for structure-function characterization and possible applications in medicine and agriculture.
... Insects use different parts of their body to cling to mating partners, to catch prey, or to defend themselves, in most cases the mouthparts or the legs. However, in 400 million years of evolution [1,2], specialized devices were independently acquired in several groups to adopt these tasks, as for instance modified legs in mantids, assassin bugs or stick insects [3][4][5], or clasping antennae of the globular springtails [6]. So far, no known species used the neck region between the head and thorax in one of these functional contexts. ...
Insects use different parts of their body to hold on to mating partners, catch prey or to defend themselves, in most cases the mouthparts or the legs. However, in 400 million years of evolution1,2, specialized devices were independently acquired in several groups to adopt these tasks, as for instance modified legs in mantids, assassin bugs or stick insects3-5, or clasping antennae of the globular springtails6. So far no known species used its neck region between the head and thorax in this context. Here we describe females of †Caputoraptor elegans, a very unusual, presumably predacious insect discovered in approximately 100 million years old7 Burmese amber. Based on several morphological features, we conclude that this species lived in the foliage of trees or bushes. A unique feature of the new taxon is a scissor-like mechanism formed by wing-like extensions on the posterior head and corresponding serrated edges of the dorsal sclerite of the first thoracic segment. Based on the specific structure of the apparatus, we conclude that it most likely was used by females to hold on to males during copulation. A defensive or prey-catching purpose appear less likely. A similar mechanism did not evolve in any other known known group of extant or extinct insects.
... In spite of their strikingly different external appearance, the assassin bug subfamilies Centrocnemidinae and Holoptilinae are closely related phylogenetically. Together with Phymatinae and Elasmodeminae, they form a monophyletic lineage within Reduviidae, usually called as the 'phymatine complex' (CARAYON et al. 1958, DAVIS 1961, SCHUH & SLATER 1995, WEIRAUCH 2008, WEIRAUCH et al. 2011). Their close evolutionary relationship makes it reasonable to treat them together in this paper. ...
The assassin bugs (Hemiptera: Heteroptera: Reduviidae) of the subfamily Centrocnemidinae and Holoptilinae of Taiwan are surveyed, the taxa are diagnosed, illustrated, and keyed. The nomenclature of the family group name Centrocnemidinae is discussed. Of this subfamily, the single species Neocentrocnemis soli (Reuter, 1881) is recognized, old records of Centrocnemis deyrollii Signoret, 1852 are considered as misidentifications of N. stali. The following synonymies are proposed: Neocentrocnemis stali (Reuter, 1881) = N. formosana (Matsumura, 1913), syn. nov., = N. baudoni Dispons, 1965, syn. nov. The male and female genitalia of N. stali are illustrated in detail, the morphology and homologies of the male intromittent organ are discussed. Of Holoptilinae, two genera and three species are recognized. The genus Locoptiris Villiers, 1943, described from the Afrotropical Region, is recorded for the first time from Taiwan; this record means also the first record of the genus in the Oriental Region. Locoptiris taiwanensis sp. nov. is described as new. Ptilocerus pendleburyi Miller, 1940, described from peninsular Malaysia, is transferred to Locoptiris. Species of Locoptiris are keyed, the relationships within the genus are discussed. Ptilocerus immitis Uhler, 1896, so far known only from Japan, is recorded for the first time from Taiwan.
... This group has also evolved diverse morphological and behavioral adaptations for prey capture that include various modifications of the forelegs 6,11-18 , such as hairy attachment structures known as the "fossula spongiosa", chelate or subchelate forelegs, elaborate armature, and the application of sticky substances ("sticky traps"). These leg modifications are thought to be important for tightly gripping prey before the toxic saliva takes its immobilizing effect 13,16,[18][19][20][21][22][23][24] (Fig. 1). We here collectively refer to such modified forelegs as raptorial legs. ...
Assassin bugs (Reduvioidea) are one of the most diverse (>7,000 spp.) lineages of predatory animals and have evolved an astounding diversity of raptorial leg modifications for handling prey. The evolution of these modifications is not well understood due to the lack of a robust phylogeny, especially at deeper nodes. We here utilize refined data from transcriptomes (370 loci) to stabilize the backbone phylogeny of Reduvioidea, revealing the position of major clades (e.g., the Chagas disease vectors Triatominae). Analyses combining transcriptomic and Sanger-sequencing datasets result in the first well-resolved phylogeny of Reduvioidea. Despite amounts of missing data, the transcriptomic loci resolve deeper nodes while the targeted ribosomal genes anchor taxa at shallower nodes, both with high support. This phylogeny reveals patterns of raptorial leg evolution across major leg types. Hairy attachment structures (fossula spongiosa), present in the ancestor of Reduvioidea, were lost multiple times within the clade. In contrast to prior hypotheses, this loss is not directly correlated with the evolution of alternative raptorial leg types. Our results suggest that prey type, predatory behavior, salivary toxicity, and morphological adaptations pose intricate and interrelated factors influencing the evolution of this diverse group of predators.
... The resin bugs (tribes Apiomerini, Diaspidiini, and Ectinoderini, also in the subfamily Harpactorinae) collect sticky plant resins which are applied to the forelegs to assist prey capture [105]-a behaviour that has recently been shown to have arisen independently in each group [106]. Raptorial forelegs with enlarged femora and/or heavy armature on the ventral surfaces of foretibia and forefemur occur in other lineages of Reduviidae, including the ambush bugs (Phymatinae) and thread-legged bugs (Emesinae) [107,108]. In venomous groups such as scorpions, coevolution of venoms and grasping forelegs (pincers) has occurred such that the two systems are complementary [109]. ...
The piercing-sucking mouthparts of the true bugs (Insecta: Hemiptera: Heteroptera) have allowed diversification from a plant-feeding ancestor into a wide range of trophic strategies that include predation and blood-feeding. Crucial to the success of each of these strategies is the injection of venom. Here we review the current state of knowledge with regard to heteropteran venoms. Predaceous species produce venoms that induce rapid paralysis and liquefaction. These venoms are powerfully insecticidal, and may cause paralysis or death when injected into vertebrates. Disulfide-rich peptides, bioactive phospholipids, small molecules such as N,N-dimethylaniline and 1,2,5-trithiepane, and toxic enzymes such as phospholipase A2, have been reported in predatory venoms. However, the detailed composition and molecular targets of predatory venoms are largely unknown. In contrast, recent research into blood-feeding heteropterans has revealed the structure and function of many protein and non-protein components that facilitate acquisition of blood meals. Blood-feeding venoms lack paralytic or liquefying activity but instead are cocktails of pharmacological modulators that disable the host haemostatic systems simultaneously at multiple points. The multiple ways venom is used by heteropterans suggests that further study will reveal heteropteran venom components with a wide range of bioactivities that may be recruited for use as bioinsecticides, human therapeutics, and pharmacological tools.
... Morphological and behavioural adaptations to predation across Reduviidae are diverse: different types of raptorial legs (e.g. Phymatinae: Weirauch et al., 2011) and tibial attachment structures (Weirauch, 2007) facilitate prey capture, and predatory strategies involve 'fishing' for termites (e.g. Salyavatinae: McMahan, 1983) and luring of ants (certain Holoptilinae: McKeown, 1945). ...
Sticky trap predation, the use of adhesive substances to trap and capture prey, is an intriguing yet poorly studied predatory strategy. Unique among known sticky trap predators, assassin bugs (Reduviidae) have evolved both exogenous and endogenous sticky trap predatory mechanisms: some trap their prey with sticky plant resins, some scavenge insects entrapped by sticky plant trichomes and others self-produce sticky secretions. The evolution of these different strategies in assassin bugs is poorly understood due to the lack of comprehensive phylogenies. We reconstruct a phylogeny of Reduviidae (141 taxa; > 5000 bp) focusing on the Harpactorinae and Bactrodinae that engage in sticky trap predation. Ancestral state reconstruction, and temporal and geographical divergence analyses show that sticky trap predation techniques in assassin bugs evolved at least seven times independently since the late Cretaceous: use of sticky plant trichomes evolved as many as four times, resin-use twice independently and once as a transition from trichome use, and 'self-stickiness' once. Exogenous and endogenous sticky traps first appeared in the Neotropics, with the two exogenous mechanisms (resin and trichome use) subsequently evolving independently in the Old World. This study illustrates, for the first time, the complex evolutionary pattern of sticky trap predation within assassin bugs.
... The subfamily of ambush bugs or Phymatinae is a distinctive group of assassin bugs (Hemiptera: Heteroptera: Reduviidae) containing four tribes, about 27 genera and 300 species distributed worldwide (Froeschner & Kormilev 1989). Except for the small tribe Themonocorini the rest of the tribes, i.e. the vast majority of the subfamily, are characterized by the peculiar, subchelate or chelate raptorial fore legs (Weirauch et al. 2011). ...
Doesburgella gen. nov. and its type species D. dilatata sp.nov (Hemiptera, Heteroptera: Reduviidac, Phymatinae; Macrocephalini) are described from South Africa.
... However, except for the work of Hasan (1990) and the unpublished thesis of Bonatto (1988), little attention has been given to the Pentatomidae, the most diverse group in the superfamily. Because the Pentatomidae have lower macrostructural variation compared to other groups of the Heteroptera (e.g., Schuh, 1975;Weirauch et al., 2011), the anterior legs have been neglected as taxonomic characters. ...
Heteropteran legs are very diverse within and among taxa, and such variation is frequently correlated with life habits. Structural modifications are commonly present in the legs of the Pentatomoidea but are poorly studied. Using scanning electron microscopy, the pretarsal microstructure of species representing all families of the Pentatomoidea (i.e., Acanthosomatidae, Canopidae, Cydnidae, Dinidoridae, Lestoniidae, Parastrachiidae, Pentatomidae, Phloeidae, Plataspididae, Scutelleridae, Tessaratomidae, Thaumastellidae, and Urostylididae) was described. The generalized pentatomoid pretarsus comprise paired claws, pulvilli, and parempodial sclerites with paired parempodial setae, a median sclerite, and the unguitractor plate, all of which are connected to one another by membranous areas. Variation can be found in the claws, pulvilli and parempodia. The claws are usually smooth in pentatomoids, but the claws of Urostylididae and Acanthosomatidae bear setae at the outer surface. The pulvilli, large and robust, are divided into basi- and distipulvilli. Pulvilli that are long and narrow, usually flattened, and undivided into basi- and distipulvilli are found on some Cydnini and Geotomini (Cydnidae), on the Phloeidae, and on the Phyllocephalinae (Pentatomidae); while the absence of pulvillar structures has been documented only for Scaptocoris minor (Cydnidae). The parempodial projections are variable in the pentatomoid families, whereas in the Thyreocoridae they are elongate with an acute apex. The taxonomic and phylogenetic relevance of pretarsal traits are discussed on the light of the current Pentatomoidea phylogenetic hypothesis.
... A diverse array of predation methods and associated morphological structures exists in Reduviidae or assassin bugs. Thread-legged bugs (Emesinae) possess raptorial fore legs that resemble those of preying mantises (Wygodzinsky 1966), species of ambush bugs (Phymatinae) have highly modified sub-chelate or chelate fore legs (Weirauch et al. 2010b) and feather-legged bugs (Holoptilinae) lure their ant prey with secretions from specialized abdominal glands (Weirauch and Cassis 2006;Weirauch et al. 2010a). Additional recent studies have focused on the fossula spongiosa, an adhesive structure on the tibiae that aids in prey capture and is widespread in Reduviidae and other Cimicomorpha (Weirauch 2007;Schuh et al. 2009). ...
Zhang, G. and Weirauch, C. 2011. Sticky predators: a comparative study of sticky glands in harpactorine assassin bugs (Insecta: Hemiptera: Reduviidae). — Acta Zoologica (Stockholm) 00 : 1–10.
For more than 50 years, specialized dermal glands that secrete sticky substances and specialized setae have been known from the legs of New World assassin bugs in the genus Zelus Fabricius (Reduviidae: Harpactorinae). The gland secretions and specialized ‘sundew setae’ are involved in enhancing predation success. We here refer to this predation strategy as ‘sticky trap predation’ and the specialized dermal glands as ‘sticky glands’. To determine how widespread sticky trap predation is among Reduviidae, we investigated taxonomic distribution of sticky glands and sundew setae using compound light microscopical and scanning electron microscopical techniques and sampling 67 species of Reduviidae that represent 50 genera of Harpactorini. We found sticky glands in 12 genera of Harpactorini and thus show that sticky trap predation is much more widespread than previously suspected. The sticky glands vary in shape, size and density, but are always located in a dorsolateral position on the fore tibia. Sundew setae are present in all taxa with sticky glands with the exception of Heza that instead possesses unique lamellate setae. The sticky trap predation taxa are restricted to the New World, suggesting a New World origin of this unique predation strategy.
... However, except for the work of Hasan (1990) and the unpublished thesis of Bonatto (1988), little attention has been given to the Pentatomidae, the most diverse group in the superfamily. Because the Pentatomidae have lower macrostructural variation compared to other groups of the Heteroptera (e.g., Schuh, 1975;Weirauch et al., 2011), the anterior legs have been neglected as taxonomic characters. ...
... Interestingly, a large number of species are either found in association with the bark of trees or dwell on foliage of herbs, shrubs, and trees [11,12,13]. Several lineages of the Phymatine Complex (Centrocnemidinae, Elasmodeminae, Hammacerinae, Holoptilinae, Phymatinae) [14,15,16], the sister group to a clade that comprises the majority of Reduviidae, the ''Higher Reduviidae'', are associated with the bark of trees and this association also occurs in various lineages within the Higher Reduviidae, which may infer that this association is ancestral for assassin bugs. Vegetation dwelling as a lifestyle, in contrast, occurs in more derived clades, e.g., the Phymatini among the Phymatinae and the Harpactorini among the Harpactorinae, and might therefore represent a derived microhabitat associations. ...
Assassin bugs are one of the most successful clades of predatory animals based on their species numbers (∼6,800 spp.) and wide distribution in terrestrial ecosystems. Various novel prey capture strategies and remarkable prey specializations contribute to their appeal as a model to study evolutionary pathways involved in predation. Here, we reconstruct the most comprehensive reduviid phylogeny (178 taxa, 18 subfamilies) to date based on molecular data (5 markers). This phylogeny tests current hypotheses on reduviid relationships emphasizing the polyphyletic Reduviinae and the blood-feeding, disease-vectoring Triatominae, and allows us, for the first time in assassin bugs, to reconstruct ancestral states of prey associations and microhabitats. Using a fossil-calibrated molecular tree, we estimated divergence times for key events in the evolutionary history of Reduviidae. Our results indicate that the polyphyletic Reduviinae fall into 11-14 separate clades. Triatominae are paraphyletic with respect to the reduviine genus Opisthacidius in the maximum likelihood analyses; this result is in contrast to prior hypotheses that found Triatominae to be monophyletic or polyphyletic and may be due to the more comprehensive taxon and character sampling in this study. The evolution of blood-feeding may thus have occurred once or twice independently among predatory assassin bugs. All prey specialists evolved from generalist ancestors, with multiple evolutionary origins of termite and ant specializations. A bark-associated life style on tree trunks is ancestral for most of the lineages of Higher Reduviidae; living on foliage has evolved at least six times independently. Reduviidae originated in the Middle Jurassic (178 Ma), but significant lineage diversification only began in the Late Cretaceous (97 Ma). The integration of molecular phylogenetics with fossil and life history data as presented in this paper provides insights into the evolutionary history of reduviids and clears the way for in-depth evolutionary hypothesis testing in one of the most speciose clades of predators.
... Reduviidae, the largest family of terrestrial predatory Hemiptera, consists of approximately 7000 species [10]. Both mitochondrial and nuclear ribosomal genes have been used as molecular markers to resolve the phylogenetic relationship in Reduviidae [10,11]. However, the number of subfamilies and their phylogenetic relationship are still at the point of juncture because the resolution is rather limited using specific gene markers [10]. ...
The 16, 470 bp nucleotide sequence of the mitochondrial genome (mitogenome) of an assassin bug from the reduviid subfamily Harpactorinae, Agriosphodrus dohrni, has been revealed. The entire genome encodes for two ribosomal RNA genes (rrnL and rrnS), 22 transfer RNA (tRNA) genes, 13 protein-coding genes, and a control region. The nucleotide composition is biased toward adenine and thymine (A+T = 72.2%). Comparative analysis with two other reduviid species Triatoma dimidiata and Valentia hoffmanni, exhibited highly conserved genome architectures including genome contents, gene order, nucleotide composition, codon usage, amino acid composition, as well as genome asymmetry. All protein-coding genes use standard mitochondrial initiation codons (methionine and isoleucine), except that nad1 starts with GTG. All tRNAs have the classic clover-leaf structure, except that the dihydrouridine (DHU) arm of tRNA(Ser(AGN)) forms a simple loop. Secondary structure comparisons of the two mitochondrial ribosomal subunits among sequenced assassin bugs show that the sequence and structure of rrnL is more conservative than that of rrnS. The presence of structural elements in the control region is also discussed, with emphasis on their implications in the regulation of replication and/or transcription of the reduviid mitogenome. The phylogenetic analyses indicated that within Reduviidae, Harpactorinae is a sister group to the Salyavatinae + Triatominae clade.
Evolutionary novelties are commonly identified as drivers of lineage diversification, with key innovations potentially triggering adaptive radiation. Nevertheless, testing hypotheses on the role of evolutionary novelties in promoting diversification through deep time has proven challenging. Here we unravel the role of the raptorial appendages, with evolutionary novelties for predation, in the macroevolution of a predatory insect lineage, the Superfamily Mantispoidea (mantidflies, beaded lacewings, thorny lacewings, and dipteromantispids), based on a new dated phylogeny and quantitative evolutionary analyses on modern and fossil species. We demonstrate a single origin of the raptorial foreleg and its associated novelties as key innovations triggering an early radiation of raptorial mantispoids from the Late Triassic to the Early Jurassic. Subsequently, the evolution of the raptorial foreleg influenced the diversification in different modes among lineages. At times, it might have limited the morphological diversity of other body parts and lead to lineage constraint by intensifying competition and lowering environmental resilience, e.g., in thorny lacewings, whose extant diversity is meagre. Conversely, in mantidflies, reduced emphasis on foreleg novelties and increased plasticity in other body parts may lead to better adaptation to predator-prey interactions and environmental shifts, thus maintaining a stable or accelerated level of diversification. We also reveal how major environmental change and lineage interactions interplayed with raptorial novelties in shaping the significant oscillations of mantispoid diversification over deep time, especially the abrupt shift near the mid-Cretaceous. However, by excluding a substantial portion of samples from the mid-Cretaceous of Myanmar, these shifts of some evolutionary parameters, such as morphological disparity, body size, and diversification rates, became inconspicuous and might be overestimated due to sampling bias. Our results uncover the intricate evolutionary patterns and profound significance of raptorial specializations, providing new insights into the role of novelties in forming evolutionary trajectories, both for the better and worse. [evolutionary novelty; macroevolution; diversification; raptorial foreleg; fossil; insect; Mantispoidea] Downloaded from https://academic.oup.com/sysbio/advance-article/doi/10.1093/sysbio/syae068/7907796 by guest on 03 December 2024
Myanmar amber is known to provide fossils of the group Insecta with surprising morphologies. Here we present fossils of the new species Gryllobencain patrickmuelleri n. gen., n. sp. from Myanmar amber that possess an overall “orthopteroid” morphology, hence resemble crickets. Unlike in most crickets, thorax appendages 1 and 2 (“legs”) are large and prominent, even in comparison to thorax appendage 3. Furthermore, thorax appendages 1 and 2 are able to fold against themselves and are armed with prominent spine-like setae, indicating that these legs were originally used for grasping prey. Most prominent is a large spine on the tibia of both appendages distantly reminding of the tibial spur or claw of praying mantises. Comparable prey-catching apparatuses have evolved repeatedly in the group Polyneoptera: gladiators (Mantophasmatodea), three ingroups of bush-crickets (Saginae, Austrosaginae, Listroscelidinae) as well as one species of fossil mantises (Santanmantis axelrodi Grimaldi, 2003) appear to have used thorax appendages 1 and 2 for prey catching. The new fossils do not seem to be closely related to any of these groups. They differ especially by prominent cerci equipped with numerous, probably mechano-sensorial setae. In the other five groups, the cerci are significantly smaller, often indistinct. The fossils furthermore have prominent maxillae with sickle-shaped proximal parts and well-armed large palps, indicating that the maxillae played an important role in processing the prey. While the thorax appendages hence represent a case of clear convergent evolution, the uniqueness of the feeding apparatus leads us to recognise the fossils as a highly specialised new species.
Arthropod behaviour is usually explained through ‘hard-wired’ motor routines and learning abilities that have been favoured by natural selection. We describe observations in which two arthropods solved rare and perhaps completely novel problems, and consider four possible explanations for their behaviours: (i) the behaviour was a pre-programmed motor routine evolved to solve this particular problem, or evolved for other functions but pre-programmed to be recruited for this function under certain conditions; (ii) it was learned previously; (iii) it resulted by chance; or (iv) it was the result of insightful behaviour. Pre-programmed solutions can be favoured by natural selection if they provide solutions to common or crucial problems. Given the apparent rarity of the problems that these animals solved, the solutions they employed are unlikely to represent innate behaviour. Learning and random chance seem unlikely, although we cannot rule them out completely. Possibly these animals employed some degree of insight.
Ambush bugs (Hemiptera: Reduviidae: Phymatinae) are sit‐and‐wait predators of flower‐visiting insects including pollinators. Broad species distribution ranges, intraspecific polymorphism, sexual dimorphism and subtle interspecific differences all contribute to making species delimitation especially difficult in this group, which is used as a model in the study of interactions between sexual dimorphism and sexual selection. Species boundaries among Nearctic ambush bugs in the common and frequently collected erosa species group (11 species, nine subspecies) have therefore remained unclear, resulting in a complex and poorly justified taxonomy. Recent molecular phylogenetic research suggested that several widespread Nearctic species are para‐ or polyphyletic. We here build on this research, integrating geometric morphometrics, molecular species delimitation approaches and host plant association data to provide a comprehensive dataset with respect to both taxon and character sampling with the goal of teasing apart evolutionary lineages of Nearctic Phymata Latreille. Although molecular‐based species delimitation analyses suggested a variety of species hypotheses, probably as a result of striking discordance between mitochondrial and nuclear ribosomal genes, the combination of these with geometric morphometric data enabled us to confidently delimit several of these problematic taxa. In addition, geometric morphometric analysis of pronotal shape revealed undocumented morphological patterns that appear to be useful in the diagnosis of many of the surveyed taxa. The results from this study provide an objective foundation for the much‐needed taxonomic revision of the most ubiquitous ambush bugs in North America.
Multiple predatory insect lineages have developed a raptorial lifestyle by which they strike and hold prey using modified forelegs armed with spine-like structures and other integumentary specialisations. However, how structures enabling the raptorial function evolved in insects remains largely hypothetical or inferred through phylogeny due to the rarity of meaningful fossils. This is particularly true for mantidflies (Neuroptera: Mantispidae), which have a scarce fossil record mostly based on rock compressions, namely isolated wings. Here, Aragomantispa lacerata gen. et sp. nov. is described from ca. 105-million-year-old San Just amber (Spain), representing the oldest and one of the few mantidflies hitherto described from amber. The fossil shows exquisitely preserved forefemoral spine-like structures composed of integumentary processes each bearing a modified seta, and prostrate setae on foretibiae and foretarsi. The fine morphology of these structures was unknown in fossil mantidflies. An assessment of integumentary specialisations from raptorial forelegs across mantispoid lacewings is provided. The present finding reveals how the specialised foreleg armature associated to the raptorial lifestyle in extant mantidflies was present yet not fully established by the Early Cretaceous, at least in some lineages, and provides palaeontological evidence supporting certain evolutionary patterns of acquisition of integumentary specialisations related to the raptorial function in the group.
Assassin bugs (Hemiptera, Heteroptera, Reduviidae) have diverse and complex morphological and behavioral adaptations for prey capture. Several of these morphological adaptations occur on the proleg. The prolegs of Emesinae are typically raptorial and they are used for grooming, grasping and hunting prey. Several morphological characters that define Emesinae as a group are found on the proleg, such as the anterior opening of the acetabula, the elongation of the procoxa, and the lateral (campaniform) sensilla on the protibia. Metapterini comprises 28 genera and approximately 280 described species, and are characterized by a conspicuous basal process of the anteroventral series of the profemur, and highly modified pretarsal structures. In this study, structures of the proleg are documented for 13 genera of Metapterini, using stereomicroscopy and scanning electron microscopy (SEM). Detailed descriptions and digital macrophotographs are provided for most of the genera for the first time, and from this morphological documentation 38 phylogenetic characters are coded, presented as a data matrix, and analyzed cladistically, and their potential usefulness for resolving relationships among Metapterini is discussed.
A small morphological variation of an organ may cause a major change of its function in animal evolution. The function of decapod chela varies considerably among taxa, between sex, and even within an individual, but also retains a simple mechanism of motion. Therefore, the decapod chela is a suitable structure to study the evolutionary process of functional diversifications, although the relationship of form and function is inadequately understood, yet. We estimated the mechanical advantages of pinching and passive disarticulation resistance, and chela size relative to the carapace in 317 chelae of 168 decapod specimens, and compared these indices with the functions of each chela. Our study revealed that mechanical advantages of pinching efficiency and passive disarticulation resistance were greatest in shell-crushing chelae, followed by gripping and pinching chelae, whereas the chela size relative to the carapace was not related to differences among these functions. We also found that the chelae are designed to retain the ratio between depth and width of the proximal dactylus. In the evolutionary process of decapods, the diversifications of chela functions were accompanied by the diversifications of the mechanical advantages, and played an essential role in their ecological diversification. J. Morphol., 2016. © 2016 Wiley Periodicals, Inc.
Abstract A review of Heteroptera classification, biogeography, and phylogeography is presented. The use of molecular data significantly expanded the knowledge of phylogenetic relationships among and within heteropteran infraorders. However, taxa historically less studied continue to receive little attention. Promising, new molecular approaches with increased genetic markers and broader taxon sampling, as well as new morphological approaches (e.g., microtomography), are the future for more stable classifications and a better comprehension of the heteropteran evolutionary history, but their application is still incipient. A non-exhaustive overview of studies about Neotropical heteropteran biogeography is made and discussed, including those about intercontinental connections and regional distribution patterns.
The most comprehensible studies, and more promising area, seem to be the one
focused on distribution patterns, especially employing macroecological methods,
and trying to elucidate what are the major factors responsible for the distribution of
the group in the Neotropics. Finally, we present an overview of phylogeographic
studies involving Neotropical Heteroptera. It is clear that the best biogeographic
and phyllogeographic studied groups are those with medical and economical importance
(e.g., Reduviidae and Pentatomidae).
Two species in the genus Rihirbus Stål are recognized, redescribed and illustrated. The diagnosis of the genus is slightly modified. The deposition information of Miller's type specimens is corrected. Rihirbus trochantericus Stål is newly recorded from Cambodia, Laos, Nepal, Thailand, and Vietnam. A key for the identification of species of Rihirbus is provided. The sexual dimorphism and polymorphism of this genus are briefly noted.
Flowers are sites of frequent visitation by pollinators and numerous other insect groups and thus could potentially represent high-quality resource patches for generalist predators that are able to exploit these aggregations of prey. In northeastern old-fields, the sit-and-wait predator Phymata pennsylvanica Handlirsch (Heteroptera: Phymatidae) occupies ambush sites on both inflorescences and nonflowering green plants. In 1998, a study was conducted to test the hypothesis that flowers are higher-quality hunting sites than nonflowering plants for these predators. Prey capture events were directly observed during daily and hourly checks on fifth-instar bugs placed on flowering or nonflowering ambush sites in the field. Prey capture rate, prey size, and food consumption rate did not differ significantly between the two site types. However, the taxonomic composition of the prey caught on the two site types was strongly divergent, with adult Diptera dominating on flowering sites and sap-feeding Homoptera dominating on nonflowering sites. These results indicate that there are times when flowering and nonflowering sites can be largely functionally equivalent for a predator in terms of prey capture success and suggest that nonflowering sites may be more important in the foraging ecology of P. pennsylvanica and other old-field ambush predators than has previously been realized. However, one implication of the existence of distinct prey communities on the two site types is that the relative quality of flowering versus nonflowering sites could potentially vary unpredictably among different locations or years depending on the particular dynamics of the dominant prey groups on each site type.
Sexual selection is a potent evolutionary force often invoked to explain observed cases of sexual dimorphism. However, evidence of this process operating on existing phenotypic variation is limited. We investigated whether sexual selection could account for sexual dimorphism in size and color pattern in the ambush bug Phymata americana. We considered the alternative hypothesis that dimorphism merely reflects sex differences in habitat use but found no evidence of sex differences in microhabitat during 2 sampling periods in the wild. Although the form of sexual (phenotypic) selection on male lateral color pattern varied between samples, selection consistently favored lateral coloration in males but not size. For females, weight was a consistent predictor of mating status in both the early and the late season. We performed 2 separate laboratory studies to investigate potential proximate mechanisms of sexual selection that might account for the field data. Although we found that male weight predicted male success in direct male--male competition and male courtship intensity predicted success in male--female interactions, we did not detect any role of male color pattern in either laboratory study. These data suggest that visual signaling is unlikely to play a role in the evolution of color pattern dimorphism in this species. Consistent with the field data, our laboratory results also found that female weight predicted the probability of copulation, possibly indicating that female receptivity coincides with female reproductive cycle (i.e., egg maturation). Copyright 2008, Oxford University Press.
Despite recent advances achieved by application of high-performance computing methods and novel algorithmic techniques to maximum likelihood (ML)-based inference programs, the major computational bottleneck still consists in the computation of bootstrap support values. Conducting a probably insufficient number of 100 bootstrap (BS) analyses with current ML programs on large datasets-either with respect to the number of taxa or base pairs-can easily require a month of run time. Therefore, we have developed, implemented, and thoroughly tested rapid bootstrap heuristics in RAxML (Randomized Axelerated Maximum Likelihood) that are more than an order of magnitude faster than current algorithms. These new heuristics can contribute to resolving the computational bottleneck and improve current methodology in phylogenetic analyses. Computational experiments to assess the performance and relative accuracy of these heuristics were conducted on 22 diverse DNA and AA (amino acid), single gene as well as multigene, real-world alignments containing 125 up to 7764 sequences. The standard BS (SBS) and rapid BS (RBS) values drawn on the best-scoring ML tree are highly correlated and show almost identical average support values. The weighted RF (Robinson-Foulds) distance between SBS- and RBS-based consensus trees was smaller than 6% in all cases (average 4%). More importantly, RBS inferences are between 8 and 20 times faster (average 14.73) than SBS analyses with RAxML and between 18 and 495 times faster than BS analyses with competing programs, such as PHYML or GARLI. Moreover, this performance improvement increases with alignment size. Finally, we have set up two freely accessible Web servers for this significantly improved version of RAxML that provide access to the 200-CPU cluster of the Vital-IT unit at the Swiss Institute of Bioinformatics and the 128-CPU cluster of the CIPRES project at the San Diego Supercomputer Center. These Web servers offer the possibility to conduct large-scale phylogenetic inferences to a large part of the community that does not have access to, or the expertise to use, high-performance computing resources.
Sexual dimorphism in coloration is a taxonomically widespread phenomenon often attributed to sexual selection on visual signals. However, the ambush bug Phymata americana exhibits sexual dimorphism in coloration that has no apparent signalling function. Here we provide evidence that colour pattern in this species influences male mating success indirectly through its effect on thermoregulation. We demonstrate, using experimental manipulation, that individuals with dark colour pattern achieve higher thoracic temperatures under illumination. We also show that dark colour pattern predicted mate-searching success but only under thermally challenging conditions (i.e. cool ambient temperature). As far as we are aware, this is the first study to provide evidence that sexual dimorphism can be accounted for by sexual selection on thermoregulatory performance.
The accuracy and scalability of multiple sequence alignment (MSA) of DNAs and proteins have long been and are still important
issues in bioinformatics. To rapidly construct a reasonable MSA, we developed the initial version of the MAFFT program in
2002. MSA software is now facing greater challenges in both scalability and accuracy than those of 5 years ago. As increasing
amounts of sequence data are being generated by large-scale sequencing projects, scalability is now critical in many situations.
The requirement of accuracy has also entered a new stage since the discovery of functional noncoding RNAs (ncRNAs); the secondary
structure should be considered for constructing a high-quality alignment of distantly related ncRNAs. To deal with these problems,
in 2007, we updated MAFFT to Version 6 with two new techniques: the PartTree algorithm and the Four-way consistency objective
function. The former improved the scalability of progressive alignment and the latter improved the accuracy of ncRNA alignment.
We review these and other techniques that MAFFT uses and suggest possible future directions of MSA software as a basis of
comparative analyses. MAFFT is available at http://align.bmr.kyushu-u.ac.jp/mafft/software/.
Structural alignment of RNAs is becoming important, since the discovery of functional non-coding RNAs (ncRNAs). Recent studies, mainly based on various approximations of the Sankoff algorithm, have resulted in considerable improvement in the accuracy of pairwise structural alignment. In contrast, for the cases with more than two sequences, the practical merit of structural alignment remains unclear as compared to traditional sequence-based methods, although the importance of multiple structural alignment is widely recognized.
We took a different approach from a straightforward extension of the Sankoff algorithm to the multiple alignments from the viewpoints of accuracy and time complexity. As a new option of the MAFFT alignment program, we developed a multiple RNA alignment framework, X-INS-i, which builds a multiple alignment with an iterative method incorporating structural information through two components: (1) pairwise structural alignments by an external pairwise alignment method such as SCARNA or LaRA and (2) a new objective function, Four-way Consistency, derived from the base-pairing probability of every sub-aligned group at every multiple alignment stage.
The BRAliBASE benchmark showed that X-INS-i outperforms other methods currently available in the sum-of-pairs score (SPS) criterion. As a basis for predicting common secondary structure, the accuracy of the present method is comparable to or rather higher than those of the current leading methods such as RNA Sampler. The X-INS-i framework can be used for building a multiple RNA alignment from any combination of algorithms for pairwise RNA alignment and base-pairing probability. The source code is available at the webpage found in the Availability and requirements section.
To determine whether the presence of the ambush bug, Phymata americana Melin, would affect the behavior of insects visiting occupied flowers in the late summer, we compared rates of insect visitation during late September to Solidago odora inflorescences occupied by the ambush bug with rates of visitation to those which were unoccupied. When we considered all species of insect visitors, we found significant differences for all measures of visitation including number of visits, number of species visiting and time spent on the inflorescence. Two common late summer visitors to the flowers were workers of the honeybee, Apis mellifera, and males of the paper wasp, Polistes fuscatus. There were no differences for either species in number of visits they made to occupied as opposed to unoccupied plants, but individuals of both species spent significantly less time on occupied inflorescences. Both species changed their behavior when encountering the predator. These studies indicate that in the late summer and early fall, presence of predators on a flower head can affect the insect visits to the occupied plant.
Male ambush bugs Phymata fasciata exhibit pre- and postcopulatory mate guarding. Predictions concerning mate-guarding behavior were tested by examining relationships between guarding and reproductive condition. Field collections of paired and single individuals were used to investigate size-related mating patterns within two populations. Generally, nonassortative mating was found and is discussed in the context of very low population densities. We found significant differences in the sizes of individuals between the two populations which might be a result of different resource levels.
The main features of the phylogeny program TNT are discussed. Windows versions have a menu interface, while Macintosh and Linux versions are command-driven. The program can analyze data sets with discrete (additive, non-additive, step-matrix) as well as continuous ...
The Parsimony Ratchet1 is presented as a new method for analysis of large data sets. The method can be easily implemented with existing phylogenetic software by generating batch command files. Such an approach has been implemented in the programs DADA (Nixon, 1998) and Winclada (Nixon, 1999). The Parsimony Ratchet has also been implemented in the most recent versions of NONA (Goloboff, 1998). These implementations of the ratchet use the following steps: (1) Generate a starting tree (e.g., a “Wagner” tree followed by some level of branch swapping or not). (2) Randomly select a subset of characters, each of which is given additional weight (e.g., add 1 to the weight of each selected character). (3) Perform branch swapping (e.g., “branch-breaking” or TBR) on the current tree using the reweighted matrix, keeping only one (or few) tree. (4) Set all weights for the characters to the “original” weights (typically, equal weights). (5) Perform branch swapping (e.g., branch-breaking or TBR) on the current tree (from step 3) holding one (or few) tree. (6) Return to step 2. Steps 2–6 are considered to be one iteration, and typically, 50–200 or more iterations are performed. The number of characters to be sampled for reweighting in step 2 is determined by the user; I have found that between 5 and 25% of the characters provide good results in most cases. The performance of the ratchet for large data sets is outstanding, and the results of analyses of the 500 taxon seed plant rbcL data set (Chase et al., 1993) are presented here. A separate analysis of a three-gene data set for 567 taxa will be presented elsewhere (Soltis et al., in preparation) demonstrating the same extraordinary power. With the 500-taxon data set, shortest trees are typically found within 22 h (four runs of 200 iterations) on a 200-MHz Pentium Pro. These analyses indicate efficiency increases of 20×–80× over “traditional methods” such as varying taxon order randomly and holding few trees, followed by more complete analyses of the best trees found, and thousands of times faster than nonstrategic searches with PAUP. Because the ratchet samples many tree islands with fewer trees from each island, it provides much more accurate estimates of the “true” consensus than collecting many trees from few islands. With the ratchet, Goloboff's NONA, and existing computer hardware, data sets that were previously intractable or required months or years of analysis with PAUP* can now be adequately analyzed in a few hours or days.
Oxythyreus slateri spec. nov. and O. cylindricornis schuhi subspec. nov. are described from South Africa. Notes on the other species of the genus and a key to the species are added.
New descriptive and distributional data are presented for Ambush bugs from the Dominican Republic: Phymatocoris iviei gen. nov., spec. nov. and Lophoscutus hispaniolensis spec. nov. New records are given for Phymata interjecta Dudich, 1922, Lophoscutus confusus Kormilev, 1989, and L. ypsilon Kormilev, 1990. Keys are given for the American genera of Macrocephalinae, and for the Caribbean species of the genus Lophoscutus.
New methods for parsimony analysis of large data sets are presented. The new methods are sectorial searches, tree-drifting, and tree-fusing. For Chase et al.'s 500-taxon data set these methods (on a 266-MHz Pentium II) find a shortest tree in less than 10 min (i.e., over 15,000 times faster than PAUP and 1000 times faster than PAUP*). Making a complete parsimony analysis requires hitting minimum length several times independently, but not necessarily all “islands” for Chase et al.'s data set, this can be done in 4 to 6 h. The new methods also perform well in other cases analyzed (which range from 170 to 854 taxa).
Evidences of the identity of the veins of the cubitalanal field of the hemipterous wing are given. In the fore wing of auchenorrhynchous Homoptera these veins are: Cm (anterior to the clavus) ; Cu2 (closely associated with the claval furrow) ; Pcu, 1st A, and 2d A (in the clavus). In Heteroptera Cu2 is absent, and the clavus contains only Pcu and 1st A. There is no anal lobe in either suborder, the clavus representing the postcubital region of the fore wing. In the hind wing of Auchenorrhyncha the veins of the cubital-anal field are the same as in the fore wing; a cubital furrow lies just behind Cu2, and the anal fold lies just behind 1st A. In Heteroptera this region of the hind wing is similar, except that Cu2 is absent, and the cubital furrow often is bifid and may contain secondary veins between its branches. In both Auchenorrhyncha and Heteroptera the anal lobe of the hind wing usually is well developed, and the jugal lohe is always absent. In the Cimicomorpha the hind-wing venation of the Miridae, Nabidae, Microphysidae, Anthocoridae, Joppeicidae, Thaumastocoridae, and Velocipedidae is of the same basic type, characterized particularly by the absence of Sc and by having a Y- or V-shaped pattern of Pcu and 1st A. The tingids resemble this group, but have a distinct Sc. The nabids and microphysids seem exceptional in sometimes having R and M separated distally, as in the Pentatomomorpha. The reduviid venation is distinct from that of the other Cimicomorpha, and is best characterized by a narrow postcubital sector containing subparallel Pcu and 1st A veins. Venation is useful in distinguishing subfamilies of the Nabidae. Anthocoridae, and Reduviidae; in the Reduviidae it serves in characterizing three major groups of subfamilies.
The present paper is the result of a study of as many North American species of this family as could be obtained. Approximately three thousand five hundred specimens were examined, and several undescribed species were encountered in both of the genera found in this region, namely, Phymata and Macrocephalus. Most of the work on the North American forms has been done by Europeans, especially Handlirsch and Melin. These authors, however, studied relatively few specimens so that several species remained undescribed. These have been lumped under the old names by American workers, as has been shown by the names applied to specimens received for study. Further study of forms that appear new but are represented by too few specimens to warrant hasty conclusions, is necessary before a complete revision is published. The writer hopes to complete such a revision in the near future, and will be very glad to receive material for determination from North and Central America.
The main features of the phylogeny program TNT are discussed. Windows versions have a menu interface, while Macintosh and Linux versions are command-driven. The program can analyze data sets with discrete (additive, non-additive, step-matrix) as well as continuous characters (evaluated with Farris optimization). Effective analysis of large data sets can be carried out in reasonable times, and a number of methods to help identifying wildcard taxa in the case of ambiguous data sets are implemented. A variety of methods for diagnosing trees and exploring character evolution is available in TNT, and publication-quality tree-diagrams can be saved as metafiles. Through the use of a number of native commands and a simple but powerful scripting language, TNT allows the user an enormous flexibility in phylogenetic analyses or simulations.
© The Willi Hennig Society 2008.
The head of Lethocerus, unlike that of many Hydrocorisae, does not vary extensively from the typical heteropteran cephalic plan. Its skeletomusculature is here described, and the possible derivation of some cephalic structures is discussed. Lethocerus is large enough to permit a detailed examination of such features as the salivary pump, the labial holdfast, and the opening of the maxillary gland. Of special interest are (1) the possible persistence of anterior tentorial pits and an epicranial suture in the adult, (2) peculiarly shaped antennae, concealed in dome-like subocular invagination of the exoskeleton, and (3) the presence of filtering devices in the cibarial food pump.
Abstract With more than 6600 species worldwide, Reduviidae (Insecta: Heteroptera), or assassin bugs, form the second largest and one of the most diverse groups of true bugs. The poor condition of the higher-level classification of Reduviidae is reflected by the facts that different authors recognize between 21 and 32 subfamily-level names and that Reduviidae were never subjected to a rigorous cladistic analysis using an exemplar approach. In the present study, a cladistic analysis of higher-level taxa of Reduviidae based on 162 morphological characters and 75 ingroup and outgroup species is presented. Twenty-one subfamily-level taxa of Reduviidae were examined, accounting for 28 tribes. In addition to characters previously used for diagnosis in Reduviidae, information on recently published character complexes is used in the present analysis, supplemented with new character information gathered specifically for this project. Reduviidae are supported as a monophyletic group with Pachynomidae as their sister taxon. The major results of this study are the support of a sistergroup relationship of Hammacerinae with the remaining Reduviidae, the monophyly of the Phymatine Complex, the relatively basal position of Harpactorinae within Reduviidae as well as a novel hypothesis on the relationships within this group, and the sistergroup relationship of Ectrichodiinae + Tribelocephalinae and their placement in a clade that also contains Emesinae, Saicinae, and Visayanocorinae. The analysis further supports a clade formed by paraphyletic Salyavatinae + Sphaeridopinae, renders Vesciinae non-monophyletic, and demonstrates the polyphyly of Reduviinae. Pseudocetherinae are shown to group with some Reduviinae. Triatominae are supported as a monophyletic group and are nested among additional Reduviinae and Stenopodainae.
list of Afrotropical Phymatinae; distribution. Goellneriana deckerti gen. nov. & spec. nov. (Heteroptera: Reduviidae: Phymatinae: Macrocephalini) from Namibia is described and illustrated. Keys to the tribes and to the Afrotropical genera and species of the subfamily Phymatinae are included, a checklist and a distribution map of the Afrotropical ambush bugs is added.
The first comprehensive cladistic analysis of Reduviidae, the assassin bugs, based on molecular data is presented and discussed in the context of a recently-published morphological analysis. Assassin bugs are essential components of ecosystems, but also important in agriculture and medicine. Sampling included 94 taxa (89 Reduviidae, 5 outgroups) in 15 subfamilies and 24 tribes of Reduviidae and is based on ∼3300 base pairs of mitochondrial (16S) and nuclear (18S, 28SD2, 28SD3-5) ribosomal DNA. Partitions of the dataset were aligned using different algorithms implemented in MAFFT and the combined dataset was analyzed using parsimony, partitioned maximum likelihood and partitioned Bayesian criteria. Clades recovered in all analyses, independent of alignment and analytical method, comprise: Cimicomorpha and Reduviidae; Hammacerinae; Harpactorinae; Apiomerini; Peiratinae; Phymatinae; Salyavatinae; Triatominae; Phymatinae + Holoptilinae; the higher Reduviidae (Reduviidae excluding Hammacerinae and the Phymatine Complex); Ectrichodiinae + Tribelocephalinae; (Triatominae + Zelurus) + Stenopodainae. Hammacerinae are rejected as sister group to all remaining Reduviidae in all analyses, as is the monophyly of Reduviinae, Emesinae and Harpactorini. High support values for Triatominae imply that blood-feeding has evolved only once within Reduviidae. Stenopodainae and part of Reduviinae are discussed as close relatives to Triatominae.
Multiple alignment of DNA sequences is an important step in various molecular biological analyses. As a large amount of sequence data is becoming available through genome and other large-scale sequencing projects, scalability, as well as accuracy, is currently required for a multiple sequence alignment (MSA) program. In this chapter, we outline the algorithms of an MSA program MAFFT and provide practical advice, focusing on several typical situations a biologist sometimes faces. For genome alignment, which is beyond the scope of MAFFT, we introduce two tools: TBA and MAUVE.
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