Ctenid Spider Research Articles

Heterologous Expression of an Insecticidal Peptide Obtained from the Transcriptome of the Colombian Spider Phoneutria depilate.

Spider venoms are composed, among other substances, of peptide toxins whose selectivity for certain physiological targets has made them powerful tools for applications such as bioinsecticides, analgesics, antiarrhythmics, antibacterials, antifungals and antimalarials, among others. Bioinsecticides are an environmentally friendly alternative to conventional agrochemicals. In this paper, the primary structure of an insecticidal peptide was obtained from the venom gland transcriptome of the ctenid spider Phoneutria depilata (Transcript ID PhdNtxNav24). The peptide contains 53 amino acids, including 10 Cys residues that form 5 disulfide bonds. Using the amino acid sequence of such peptide, a synthetic gene was constructed de novo by overlapping PCRs and cloned into an expression vector. A recombinant peptide, named delta-ctenitoxin (rCtx-4), was obtained. It was expressed, folded, purified and validated using mass spectrometry (7994.61 Da). The insecticidal activity of rCtx-4 was demonstrated through intrathoracic injection in crickets (LD50 1.2 μg/g insect) and it was not toxic to mice. rCtx-4 is a potential bioinsecticide that could have a broad spectrum of applications in agriculture.

The hitherto unknown male of Bowie indicus (Gravely, 1931) (Araneae: Ctenidae)

ABSTRACT The hitherto unknown male of the ctenid spider species Bowie indicus (Gravely, 1931) is described and illustrated in detail.

Four new species of ctenid spiders (Araneae, Ctenidae) from Southeast Asia, with the first description of the female of Sinoctenuszhui Marusik, Zhang & Omelko, 2012.

The spider family Ctenidae Keyserling, 1877 has a worldwide distribution with 580 species belonging to 49 genera, of which 109 species of six genera are distributed in Southeast Asia. Four new species of ctenid spiders are described from Southeast Asia: Anahitamenglun sp. n. (Yunnan, China), Bowiehaiphong sp. n. (Hai Phong, Vietnam), Bowiemengla sp. n. (Yunnan, China) and Bowiezhengi sp. n. (Yunnan, China). In addition, the female of Sinoctenuszhui Marusik, Zhang & Omelko, 2012 (Hainan, China) is described for the first time.

A survey of ctenid spiders (Araneae, Ctenidae) from Xishuangbanna Tropical Botanical Garden, Yunnan, China.

Amauropelma Raven, Stumkat & Gray, 2001 currently contains 24 species. It is distributed in Australia, India, Indonesia, Laos and Malaysia. This genus has not been found in China. Ctenus Walckenaer, 1805 comprises 213 known species. This genus is distributed worldwide. Currently, only two species, Ctenuslishuqiang Jäger, 2012 and Ctenusyaeyamensis Yoshida, 1998 are known to occur in China. Three new species of ctenid spiders are described from Xishuangbanna Tropical Botanical Garden in Yunnan Province, China: Amauropelmayunnan sp. nov., Ctenusbanna sp. nov. and Ctenusyulin sp. nov. Amauropelma and Ctenusrobustus Thorell, 1897 are reported from China for the first time.

Ctenus igatu sp. nov. (Araneae: Ctenidae): a new subterranean spider from Brazil with an analysis of troglomorphic traits

In this work we describe Ctenus igatu sp. nov., the first ctenid spider from South America with conspicuous troglomorphic traits, including elongated appendages, reduction of eyes, and body depigmentation. The new species is only known to occur in a unique sandstone cave from the state of Bahia, north-eastern Brazil. The morphology of the genitalia suggests that Ctenus igatu sp. nov. is closely related to Ctenus fasciatus Mello-Leitão, 1943, a facultative subterranean species from caves in the state of São Paulo, south-eastern Brazil. In addition, we compared morphological traits possibly related to the isolation in subterranean habitats, such as ratios between carapace length vs. leg IV length and eye diameters vs. carapace length, of 19 species of Ctenus (17 epigean species, C. fasciatus and the new troglobitic species described herein). Our analysis showed that both C. fasciatus as C. igatu sp. nov. have morphological troglomorphisms, with C. igatu sp. nov. showing marked specializations to subterranean life.

Effect of forest succession and microenvironmental variables on the abundance of two wandering spider species (Araneae: Ctenidae) in a montane tropical forest

This study assessed the effects of forest succession and microenvironmental variables on the abundance of ctenid spiders in a montane tropical forest in Costa Rica. We surveyed 20 plots (5 × 5 m) in both primary and secondary forest for a total of 40 samples measuring the following variables: leaf litter depth, canopy density, slope, number of trees above 3 m and average stem diameter of trees exceeding 3 m in height. A total of 150 adult and subadult specimens belonging to five species were observed. The most abundant species were Spinoctenus escalereteHazzi et al., 2018 which has not previously been recorded in Central America and Kiekie griswoldiPolotow & Brescovit, 2018. The larger species, K. griswoldi was significantly more abundant in primary than in secondary forest. Conversely, S. escalerete was more abundant in the secondary forest. A generalized linear model indicated that the most important variable influencing ctenids abundance was leaf litter depth. Whereas the abundance of K. griswoldi was positively related with leaf litter depth, the abundance of S. escalerete was negatively related to litter depth. Thus, forest succession and leaf litter are important factors that influence the abundance of floor ctenid community and may allow the coexistence of co-occurring species.

Visual pathways in the brain of the jumping spider Marpissa muscosa.

Some animals have evolved task differentiation among their eyes. A particular example is spiders, where most species have eight eyes, of which two (the principal eyes) are used for object discrimination, whereas the other three pairs (secondary eyes) detect movement. In the ctenid spider Cupiennius salei, these two eye types correspond to two visual pathways in the brain. Each eye is associated with its own first- and second-order visual neuropil. The second-order neuropils of the principal eyes are connected to the arcuate body, whereas the second-order neuropils of the secondary eyes are linked to the mushroom body. We explored the principal- and secondary eye visual pathways of the jumping spider Marpissa muscosa, in which size and visual fields of the two eye types are considerably different. We found that the connectivity of the principal eye pathway is the same as in C. salei, while there are differences in the secondary eye pathways. In M. muscosa, all secondary eyes are connected to their own first-order visual neuropils. The first-order visual neuropils of the anterior lateral and posterior lateral eyes are connected with a second-order visual neuropil each and an additional shared one (L2). In the posterior median eyes, the axons of their first-order visual neuropils project directly to the arcuate body, suggesting that the posterior median eyes do not detect movement. The L2 might function as an upstream integration center enabling faster movement decisions.

Small and large spatial scale coexistence of ctenid spiders in a neotropical forest (French Guiana)

While spiders constitute the most abundant and diverse arthropods in many habitats, they remained under-studied, especially in tropical rainforests. The goal of this study is to assess the spatial distribution of the spider family Ctenidae by assessing associations of species diversity and population traits among different habitat conditions. Fieldwork was carried out during 2013 in habitats varying in flooding frequency (plateau vs. flooded forest) and elevation (inselberg vs. lowland) in the Nouragues National Natural Reserve, French Guiana. Assemblage composition, population structure, and trait measurements of one dominant species were assessed using hand collection in replicated quadrats. We found strong effects on ctenid assemblages attributable to both elevation and flooding, with changes in relative abundance of species among habitats, but few correlated densities between species. At the population level, main differences in species distribution between and within habitats were detected only when ...

Systematics and biogeography of Spinoctenus, a new genus of wandering spider from Colombia (Ctenidae)

Among ctenid spiders, ctenines comprise the most diverse subfamily. In this study, a new genus of Cteninae, Spinoctenus, is proposed to include the type species S. yotoco, sp. nov. Ten new species are also described: S. escalerete, S. pericos, S. eberhardi, S. spinosus, S. stephaniae, S. nambi, S. florezi, S. tequendama, S. chocoensis and S. flammigerus. Results of the parsimony and Bayesian phylogenetic analyses using morphological and behavioural characters indicate the monophyly of this genus, closely related to Phoneutria Perty, 1883 and Ctenus Walckenaer, 1805. This genus can be distinguished from the remaining Ctenidae by three unambiguous synapomorphies: embolus with folded process, tegulum with median process, and RTA curved internally close to the cymbium. A dispersal-vicariance biogeographical analysis of the genus in the Andean and Chocó regions indicates the origin of Spinoctenus in the Western and Central Andean Cordilleras. From this region, three events of dispersal occurred to the other regions (one to the Chocó and two to the Eastern Cordillera), which were subsequently followed by three events of vicariance, suggesting that dispersal and vicariance were equally important in shaping the current distribution patterns of Spinoctenus species. The discovery of this new genus containing a large number of new species in the Andean and Chocó regions highlights the current poor knowledge of the Colombian biodiversity. http://zoobank.org/urn:lsid:zoobank.org:pub:A7DA044C-8A59-4FAE-8F3B-00D3D2498820

Studies on chromosomal characteristics of Ctenus indicus (Gravely 1931) (Araneae: Ctenidae)

The karyological information gathered for the Indian spiders taxa thus far were cytologically derived from only few species but none for the representatives belonging to the genus Ctenus. Ctenus indicus (Gravely 1931), an Indian ctenid spider was cytogenetically analyzed following conventional, C- and NOR-banding techniques so as to gather substantial data for future course of understanding of karyotypic evolution among spider species. The karyotypic data for Ctenus indicus revealed the complement consisting of (2n = 28) 26AA + X1X2♂ and (2n = 30) 26AA + X1X1X2X2♀ acrocentric chromosomes. A closer scrutiny of meiotic progression disclosed many male pachytenic cells displaying the occurrence of ‘bouquet’ formation. The results of C-banding enabled in identifying centromeric constitutive heterochromatin locales, and in some chromosomes also the distal ends of telomeric regions. Silver nitrate stained NOR-specifications were noticed at the distal telomeric regions of two pairs of chromosomes (#8 and #10) in the complement. Cytological evidence procured from the present study not only adds to the ever-growing list of the spider cytogenetic assessments but also offers as a baseline data towards establishing evolutionary relationships within this important group.

Papeles invertidos: arañas depredadoras de gusanos de terciopelo neotropicales (Epiperipatus spp.; Onychophora: Peripatidae).

Los gusanos de terciopelo (Onychophora) son antiguos depredadores de origen cámbrico que ocasionalmente consumen arañas cténidas. Aquí informamos el caso contrario: arañas (Ctenus spp.) alimentándose de gusanos onicóforos (Epiperipatus spp.) en Colombia y Costa Rica. Aparentemente las presas no lograron expulsar su red defensiva y la eficacia del veneno de araña sugiere que los nervios y músculos de los onicóforos son bioquímicamente equivalentes a los de los insectos.

Bufadienolide and alkaloid-based chemical defences in two different species of neotropical anurans are equally effective against the same arthropod predators

Abstract:Defensive chemicals in anuran skin secretions function in protection against potential predators. Although studies have demonstrated that particular chemicals are effective against certain predators, very little is known about how different chemicals from different species function against the same predators. Understanding how different chemicals function as a defence against similar predators is fundamental to the ecology and evolution of chemical defences in frogs. In the present study, the defensive function of bufadienolide-based defences in adultRhaebo haematiticus(Bufonidae) were compared with alkaloid-based defences in adult and juvenileDendrobates auratus(Dendrobatidae) against the same predators. Most bufonids contain synthesized bufadienolides, whereas dendrobatids contain dietary-derived alkaloids. Predation trials were performed with two potential invertebrate predators,Paraponera clavata(bullet ant) andCupiennius coccineus(ctenid spider), to determine how these predators respond to two different types of frog chemical defence. The non-chemically defended frogCraugastor fitzingeriserved as a control in all predation trials. Our results suggest that bufadienolide defences ofR. haematiticusand alkaloid defences ofD. auratusare equally effective towards bullet ant and ctenid spider predators. The similar avoidance and cleaning behaviours exhibited by these ants and spiders after contact with bufadienolides and alkaloids suggest that both types of defence are unpalatable to these arthropod predators.

Spiders (Araneae) Found in Bananas and Other International Cargo Submitted to North American Arachnologists for Identification.

Spiders found in international cargo brought into North America are sometimes submitted to arachnologists for identification. Often, these spiders are presumed to be of medical importance because of size or a submitter's familiarity with a toxic spider genus from the continent of origin. Starting in 2006, requests were made for spiders found in international cargo brought into North America, in addition to the specimens from similar cargo shipments already in our museum collections. This was an ad hoc study that allowed us to focus on spiders of concern to the discoverer. We identified 135 spiders found in international cargo. A key for the most common species is provided. The most frequently submitted spiders were the pantropical huntsman spider, Heteropoda venatoria (L.) (Sparassidae), and the redfaced banana spider, Cupiennius chiapanensis Medina Soriano (Ctenidae). Spiders of medical importance were rare. The most common cargo from which spiders were submitted was bananas with most specimens coming from Central America, Ecuador, or Colombia. Lack of experience with nonnative fauna caused several experienced American arachnologists to misidentify harmless ctenid spiders (C. chiapanensis, spotlegged banana spider, Cupiennius getazi Simon) as highly toxic Phoneutria spiders. These misidentifications could have led to costly, unwarranted prophylactic eradication measures, unnecessary employee health education, heightened employee anxiety and spoilage when perishable goods are left unloaded due to safety concerns.

Subterranean biodiversity in the Serra da Bodoquena karst area, Paraguay river basin, Mato Grosso do Sul, Southwestern Brazil

We present herein a synthesis of faunistic data from caves in the Serra da Bodoquena karst area, middle Paraguay River basin, Mato Grosso do Sul State. Those include phreatic, submerged and dry caves. Emphasis is given to troglobites (exclusively subterranean species), potentially threatened due to their morphological, physiological and behavioral specializations, associated to generally small distributions. The Bodoquena karst area distinguishes as a spot of high diversity of troglobites, such as trichomycterid and heptapterid catfishes, aquatic planarians and gastropods, arachnids (Eusarcus opilionids, ctenid spiders), Polydesmida diplopods, several collembolans, some insects, and Peracarida crustaceans, which include interesting phylogenetic relicts as spelaeogriphaceans. Four geographic compartments corresponding to microbasins, seemingly with biogeographic importance for the subterranean fauna, are recognized. Phreatobic troglobites (Trichomycterus catfishes, aquatic peracarids, planarians) distribute widely across these compartments and some well beyond (the spelaeogriphacean Potiicoara brasiliensis reaches Mato Grosso state), while those living in base-level streams (Rhamdia and Ancistrus catfishes) and the terrestrial ones, that live in the vadose (aerated zone) are generally restricted to one compartment. Many subterranean ecosystems in Mato Grosso do Sul are endangered by several threats described here and urgent actions for effective protection are required to guarantee a sustainable use of the land and the karst aquifers.

Defensive Responses of Neotropical Harvestmen (Arachnida, Opiliones) to Generalist Invertebrate Predators

Abstract Descriptions of defensive behaviors used by Neotropical harvestmen are rarely based upon direct observations of encounters between individuals and syntopic predators. In this study, we investigated the defensive responses exhibited by five harvestman species from Costa Rica in interactions with ctenid spiders (Cupiennius spp.), whip spiders (Phrynus pseudoparvulus), onychophorans (Epiperipatus sp.), and centipedes (Scolopendra sp.). We also observed interactions between harvestmen and a non-predatory invertebrate, the millipede Nyssodesmus python. In 64 encounters, ctenid spiders consumed 11 harvestmen, including eight Prionostemma sp., two Cynorta marginalis, and one Eupoecilaema magnum. The most frequent defensive behavior exhibited by harvestmen was fleeing. Other behaviors included aggression (striking with leg II), bobbing, leg autotomy, lying flat, and thanatosis. Prionostemma exhibited the most variable responses, especially in the presence of ctenid spiders. In addition to the lab-based e...

N-terminal aromatic residues closely impact the cytolytic activity of cupiennin 1a, a major spider venom peptide

Cupiennins are small cationic α-helical peptides from the venom of the ctenid spider Cupiennius salei which are characterized by high bactericidal as well as hemolytic activities. To gain insight into the determinants responsible for the broad cytolytic activities, two analogues of cupiennin 1a with different N-terminal hydrophobicities were designed. The insecticidal, bactericidal and hemolytic activities of these analogues were assayed and compared to the native peptide. Specifically, substitution of two N-terminal Phe residues by Ala results in less pronounced insecticidal and cytolytic activity, whereas a substitution by Lys reduces strongly its bactericidal activity and completely diminishes its hemolytic activity up to very high tested concentrations. Biophysical analyses of peptide/bilayer membrane interactions point to distinct interactions of the analogues with lipid bilayers, and dependence upon membrane surface charge. Indeed, we find that lower hemolytic activity was correlated with less surface association of the analogues. In contrast, our data indicate that the reduced bactericidal activity of the two cupiennin 1a analogues likely correspond to greater bilayer-surface localization of the peptides. Overall, ultimate insertion and destruction of the host cell membrane is highly dependent on the presence of Phe-2 and Phe-6 (Cu 1a) or Leu-6 (Cu 2a) in the N-terminal sequences of native cupiennins.

Modeling distribution of Phoneutria bahiensis (Araneae: Ctenidae): an endemic and threatened spider from Brazil

Phoneutria bahiensis Simo & Brescovit, 2001 is a large ctenid spider inhabiting the states of Bahia and Espirito Santo, Brazil. Considering that it is probably endemic, this species was included in the Brazilian red book of threatened species. Here, we predict the distribution range of P. bahiensis using 19 bioclimatic variables in the model design. The most septentrional record for this spider was indicated for northern Bahia. The model predicts that the distribution range covers the Atlantic Forest from the state of Paraiba to Rio de Janeiro, with the best suitable area in the Atlantic Forest of the state of Bahia. The bioclimatic variable with the best contribution to the model was precipitation in the driest quarter. Based on collected data, the species inhabits Ombrophilous Forests and Restinga vegetation, two ecosystems of the Atlantic Forest biome. In the best-predicted area of distribution, eleven Conservation Units were included. This information could be considered for future conservation plans of this species.

Densidades de aranhas errantes (Ctenidae e Sparassidae, Araneae) em uma floresta fragmentada

As aranhas errantes das famílias Ctenidae e Sparassidae são noturnas e podem ser encontradas principalmente no folhiço forrageando em locais próximos umas das outras na região amazônica. A coexistência entre estas aranhas sugere que elas competem por alimento e abrigos e, por serem predadores generalistas, a predação intraguilda também pode limitar a abundância de suas populações. Neste estudo, investigamos os efeitos da fragmentação florestal sobre a densidade de aranhas, cujas populações estão sujeitas ao isolamento e a redução de seus hábitats. Sete fragmentos florestais (£10 ha) e nove áreas de mata contínua (>1000 ha) foram comparados quanto à densidade das espécies de Ctenidae e Sparassidae, em uma floresta de terra-firme na Amazônia Central. Testes com ANOVA revelaram que os ctenídeos foram mais suscetíveis à fragmentação da floresta por terem suas populações reduzidas nos fragmentos onde, por outro lado, os esparassídeos foram mais abundantes. Portanto, os fragmentos estudados foram considerados ambientes alterados por não serem capazes de manter as populações destas aranhas nos níveis observados na mata contínua. Além disso, a correlação entre a densidade de ctenídeos e esparassídeos foi negativa na área de estudo (Pearson, r = -0,527, n = 16) indicando que é provável, que a competição por recursos e, talvez, a predação intraguilda tenham um papel importante no tamanho destas populações. Porém, um melhor conhecimento a respeito das interações entre as espécies de Ctenidae e Sparassidae (competição interespecífica e predação intraguilda) é fundamental para o entendimento de como a coexistência entre elas pode influenciar na suscetibilidade destas aranhas à fragmentação da floresta.

HIGHER-LEVEL RELATIONSHIPS OF THE SPIDER FAMILY CTENIDAE (ARANEAE: CTENOIDEA)

A cladistic analysis based on parsimony is undertaken to test hypotheses concerning the monophyly of the ctenid spiders and the relationships among their various clades. The data matrix comprised a total of 98 species representing 16 families scored for 146 characters, with all but six taken from various morphological systems; the remaining are behavioral attributes.Ctenidae is shown to be polyphyletic as currently delimited, but the most severely questioned taxa (i.e., Acanthoctenus, Cupiennius, and Ancylometes) are indeed members of this family. The so-called ctenid eye pattern is shown to be a synapomorphy uniting a more restricted set of taxa. This clade is recognized as Ctenidae sensu stricto and it comprises at least five major lineages: Acantheinae, Acanthocteninae, Calocteninae, Cteninae, and Viridasiinae. The latter taxa are hypothesized to be the sister group of all other ctenids. In turn, a clade formed by Miturgidae s.s. and Zoridae s.s. is proposed as the sister group of Ctenidae. The cladistic analysis also refutes the monophyly of Ctenus, Anahita, Enoploctenus, Celaetycheus, and Leptoctenus.The following taxonomic changes are proposed: Anahita isaloensis Ono, 1993 is transferred to Vulsor Simon, 1888; Diallomus Simon, 1897, currently placed in Zoridae, is transferred to Ctenidae; Tunabo Chamberlin, 1916 is synonymized with Neoctenus Simon, 1897; Neoctenus is removed from Zoridae and transferred to Trechaleidae; Xenoctenus Mello-Leitão, 1938 is removed from the synonymy of Tunabo and considered incertae sedis, within Ctenoidea.

Impact of intraguild predators on survival of a forest-floor wolf spider.

We investigated the impact of variation in densities of a guild of generalist predators on survival of young wolf spiders of the genus Schizocosa. Numbers of other spiders and centipedes were reduced by >80% in fenced 4-m2 plots in an experiment that was replicated twice in each of three forest locations. Schizocosa survival during the 1st month was low (<50%) in all three locations, but did not differ between predator-reduction and control plots. By the end of the 1st month, densities of the manipulated predators had converged in control and perturbed treatments, most likely because of reduced per capita mortality from lowered rates of intraguild predation and cannibalism in the experimental treatment. During the 2nd month of the experiment, centipedes and spiders other than Schizocosa again were removed from the experimental plots and, unlike the earlier period, numbers of intraguild predators in the predator-removal treatment remained lower than in control plots. Reducing densities of intraguild predators during the 2nd month improved survival of older juvenile Schizocosa by 75% in two of three locations on the forest floor. In addition to this evidence that intraguild predation can affect older juvenile Schizocosa, survival of Schizocosa during the last half of the experiment was negatively correlated with spatial variation in densities of gnaphosid and ctenid spiders. These two abundant families of cursorial spiders preyed on Schizocosa at a high rate in laboratory trials. Thus, variation in densities of intraguild predators did not influence the youngest Schizocosa, but did influence the survival of older juveniles, most likely due to variations in densities of other cursorial spiders.