Spiders of the genus Cupiennius Simon 1891 (Araneae,Ctenidae)

Summary Cupiennius salei (Ctenidae) is a tropical wandering spider which lives in close association with a particular type of plant (see companion paper). These plants are the channels through which the spiders receive and emit various types of vibrations. We measured the vibrations the spiders are typically exposed to when they sit on their dwelling plants (banana plant, bromeliad) in their natural biotope in Central America. In addition a laboratory analysis was carried out to get an approximate idea of the complex vibration-propagating properties of the dwelling plants, taking a banana plant as an example. (1) Types of vibrations (Figs. 1–4). Despite variability in detail there are characteristic differences in spectral composition between the vibrations of various abiotic and biotic origins: (a) Vibrations due to wind are very low frequency phenomena. Their frequency spectra are conspicuously narrow with prominent peaks close to or, more often, below 10 Hz. Vibrations due to raindrops show maximal acceleration values at ca. 1000 Hz. Their frequency band at-20 dB extends up to ca. 250 Hz where-as that of the vibrations due to wind extends to only ca. 50 Hz. (b) The frequency spectra of prey vibrations such as those generated by a running cockroach are typically broad-banded and contain high frequencies; they have largest peaks mostly between ca. 400 and 900 Hz. Their-20 dB frequency bands usually extend from a few Hz to ca. 900 Hz. Some potential prey animals such as grass-hoppers seem to be vibrocryptic; they walk by the spider as if unnoticed. Their cautious gait leads to only weak vibrations at very low frequencies resembling the background noise due to wind. Courtship signals are composed maily of low frequencies, intermediate between background noise and prey vibrations (male: prominent peaks at ca. 75 Hz and ca. 115 Hz; female: dominant frequencies between ca. 20 Hz and ca. 50 Hz). The male signal is composed of syllables and differs from all other vibrations studied here by being temporally highly ordered. A comparison with previous electrophysiological studies suggests that the high pass characteristics of the vibration receptors enhance the signal-to-(abiotic)-noise ratio and that the vibration-sensitive interneurons so far examined and found to have band pass characteristics are tuned to the frequencies found in the vibrations of biotic origin. (2) Signal propagation (Fig. 5). In terms of frequency-dependent attenuation of vibrations the banana plant is well suited for transmitting the above signals. Average attenuation values are ca. 0.35 dB/cm. Together with known data on vibration receptor sensitivity this explains the range of courtship signals of more than 1 m observed in behavioral studies. Attenuation in the plant is neither a monotonic function of frequency nor of distance from the signal source.     

Mechanism of signal production in the vibratory communication of the wandering spider Cupiennius getazi (Arachnida,Araneae)

The communication with substrate vibrations produced by vibrations of the body or its appendages is widespread among arthropods, especially among spiders. Its biomechanics, however, is poorly understood. Males of the wandering spider Cupiennius getazi produce such substrate vibrations during courtship by means of dorsoventral movements of their opisthosoma without hitting their dwelling plant.Simultaneous recordings of the plant vibrations (accelerometry), of the opisthosoma movements (laser Doppler vibrometry) and of the electromyograms of the opisthosomal depressor muscle, revealed that the main frequency of the vibratory signal of about 80 Hz originates from the activity of the opisthosomal depressor muscle. The transfer functions of the spider's body show resonances which could amplify the main frequency before it is transmitted into the plant.A low frequency component of the opisthosomal movement (duration c. 0.3 s, displacement c. 6 mm (peak-peak) 30° deflection angle, frequency 10–20 Hz) can be distinguished from a main frequency component (duration c. 0.1 s, displacement c. 0.5 mm 2.5° deflection angle, frequency c. 80 Hz). The main frequency component is superimposed on an upward movement of the low frequency component.     

Licht- und elektronenmikroskopische Untersuchungen zur Ovarentwicklung und Oogenese bei Cupiennius salei Keys. (Araneae,Ctenidae)

During the development of the ovary in Cupiennius salei the following phases in oogenesis can be observed: previtellogenic and the first and second vitellogenic. These phases are described. Formation of the oocytes, the morphology of the funiculus, yolk synthesis in connection with the haemolymph, and the further destiny of the ovarian epithelium after egg deposition find special considerations.

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Verzeichnis der Abkürzungen A Anschwellung - AG Ausführgang - ASP ampullenförmige Spinndrüse - CH Chorion - D Dictyosom - DO Dotter - DOC dotterarme Oocyte - DOS Dotterscholle - E Endocytose - EG elektronendichte Grana - ER endoplasmatisches Reticulum - F Funiculus - FK Fettkörper=Speichergewebe - FZ Funiculuszelle - HC Hämocyte - HDM hintere Dorsalmuskulatur - K Kern - KAZ Kanalzellen - KW Körperwand - KZ Keimzone - LH Leibeshöhle - LLM laterale Longitudinal-muskulatur - M Mitochondrium - MD Mitteldarm - MDD Mitteldarmdivertikel - MES Mesoderm - MLM mediane Longitudinal-muskulatur - BM Basalmembran - BSP beerenförmige Spinndrüse - BZ Begleitzellen - MS Membranstapel - MV Mikrovillus - MVB multivesiculate body - MZ Muskelzelle - N Nukleolus - OC Oocyte - I. OC Oocyte der ersten vitellogenen Phase - II. OC Oocyte der zweiten vitellogenen Phase - OG Oogonie - OV Ovidukt - OVG ovarielles Gewebe - P perivitelliner Raum - PM Plasmamembran - PV Pinocytosevesikel - PZ Peritonealzelle - SP Spinndrüse - V Vakuole - VDM vordere Dorsoventral-muskulatur - VM Vitellinmembran - WZ Wandzelle - WZW Wandzellwucherung - ZG Zwischengewebe Die Untersuchungen wurden dankenswerterweise von der Deutschen Forschungsgemeinschaft durch Sach- und Personalmittel gefördert.Herrn Prof. Dr. H.-U. Koecke danke ich für seine Unterstützung bei der Durchführung der elektronenmikroskopischen Untersuchungen.     

Male Competition over Access to Females in a Spider with Last-Male Sperm Precedence

Agonistic behaviour between male cellar spiders (Pholcus phalangioides) was investigated to test whether (1) size difference determines which male achieves access to the female, (2) males are able to monopolize access to the female until egg laying and whether (3) female resource value increases before egg laying because of last‐male sperm precedence. We further investigated whether (4) there is variation in time and energy spent on courtship and copulation depending on the degree of sperm competition, i.e. with or without rival present. In three experimental settings we introduced two males of either different or similar sizes, or a single male to a female. The mating units were constantly video‐observed until the females produced their first egg sac. Experience, ownership and female resource value in terms of body size was controlled. Our results show that larger males achieve almost exclusive access to females. Size symmetrical settings resulted in increased fighting activity and duration but dominance did not influence mating success. If copulations were disturbed by the rival male, copulations were terminated earlier in symmetrical settings compared with asymmetrical settings. In 94.8% of trials only one copulation took place, suggesting that the copulating male successfully monopolized access to the female. Males confronted with a rival copulated longer but courted significantly shorter than lone males. Although the last male to copulate sires 88% of the offspring in P. phalangioides, neither fighting nor courtship activity increased before the female laid a batch of eggs. This suggests that males have no indication of the timing of oviposition.     

Cupiennin 1, a new family of highly basic antimicrobial peptides in the venom of the spider Cupiennius salei (Ctenidae).

A new family of antimicrobial peptides was isolated from the venom of Cupiennius salei. The peptides were purified to homogeneity, and the sequence of cupiennin 1a was determined by Edman degradation: GFGALFKFLAKKVAKTVAKQAAKQGAKYVVNKQME-NH(2). The amino acid sequences of cupiennin 1b, c, and d were obtained by a combination of sequence analysis and mass spectrometric measurements of comparative tryptic peptide mapping. All peptides consist of 35 amino acid residues and are characterized by a more hydrophobic N-terminal chain region and a C terminus composed preferentially of polar and charged residues. The total charge of all cupiennins calculated under physiological conditions is +8, and their C terminus, formed by a glutamic acid residue, is amidated. Conformational studies of the peptides revealed a high helix forming potential. Antimicrobial assays on bacteria with cupiennin 1a, 1d, and synthesized cupiennins 1a* and 1d* showed minimal inhibitory concentrations for bacteria in the submicromolar range. Their lytic effect on human red blood cells was lower by a factor of 8 to 14 than the highly hemolytic melittin. Cupiennin 1a, 1b, 1d, 1a*, and 1d* showed pronounced insecticidal activity. The immediate biological effects and the structural properties of the isolated cupiennins indicate a membrane-destroying mode of action on prokaryotic as well as eukaryotic cells.     

Nocturnal Homing: Learning Walks in a Wandering Spider?

Homing by the nocturnal Namib Desert spider Leucorchestris arenicola (Araneae: Sparassidae) is comparable to homing in diurnal bees, wasps and ants in terms of path length and layout. The spiders'' homing is based on vision but their basic navigational strategy is unclear. Diurnal homing insects use memorised views of their home in snapshot matching strategies. The insects learn the visual scenery identifying their nest location during learning flights (e.g. bees and wasps) or walks (ants). These learning flights and walks are stereotyped movement patterns clearly different from other movement behaviours. If the visual homing of L. arenicola is also based on an image matching strategy they are likely to exhibit learning walks similar to diurnal insects. To explore this possibility we recorded departures of spiders from a new burrow in an unfamiliar area with infrared cameras and analysed their paths using computer tracking techniques. We found that L. arenicola performs distinct stereotyped movement patterns during the first part of their departures in an unfamiliar area and that they seem to learn the appearance of their home during these movement patterns. We conclude that the spiders perform learning walks and this strongly suggests that L. arenicola uses a visual memory of the burrow location when homing.     

Male Choice and Male-male Competition in Idotea baitica (Crustacea,Isopoda)

Sexual selection in mate-guarding Crustacea may involve several processes: male choice, male-male competition, and female choice. To evaluate the relative importance of the different processes in mate choice of the aquatic isopod I. baitica we studied 1) the mate-choice criteria of males, 2) effects of sex ratio on the outcome of the mating contest, and 3) the role of size in male-male interactions. When given a choice between a small and a large female, males most often chose the one that matured earlier for parturial ecdysis. Maturity was a more important choice criterion than female size, but these also correlated positively. Large males had a mating advantage in both male- and female-biased sex ratios; pairing was size-assortative only in the male-biased ratio where guarding was also longer. If an extra male was placed with a precopulatory pair, 30 % take-overs occurred, large males surpassing. Present and earlier work suggests that male size is an asset in both intra- and intersexual interactions. There is little or no direct phenotypic sexual selection on female size: sexual selection for large males presumably contributes to the evolution of sexual size dimorphism in I. baitica.     

Sexual Selection in the Water Spider: Female Choice and Male–Male Competition

The water spider Argyroneta aquatica is the only spider spending its whole life under water, and one of the few spider species in which males are larger than females. Previous studies indicated that males can cannibalize females, which is uncommon among spiders. Here we aimed to further test for a potential influence of sexual selection on male body size. We examined the importance of female choice by testing whether females prefer the larger of two simultaneously presented males as mating partners. Further, we examined the influence of male–male competition by comparing the fighting behaviour between large and small males when alone or when together with a female, and we determined the outcome of fights. We found that females approach and choose large males as mating partners, despite the risk of male cannibalism. Additionally, males intensively compete for females, and large males clearly win against smaller ones. Hence sexual selection seems to be important for the evolution of the peculiar sexual size dimorphism of water spiders, as large size is beneficial for males in both the intra‐ and intersexual context. Previous studies have suggested an important role of natural selection in the sex‐specific body size of water spiders, but natural and sexual selection mechanisms apparently work in the same direction, favouring large male size.     

Immunocytochemical localization and secretion process of the toxin CSTX-1 in the venom gland of the wandering spider Cupiennius salei (Araneae: Ctenidae)

Fluorescein and horseradish peroxidase-labeled monoclonal antibodies were used to localize the predominant toxic peptide CSTX-1 in the venom gland of the spider Cupiennius salei. There was no polarity of CSTX-1 expression in repleted glands, whereas the glands of previously milked spiders showed a decreasing immunofluorescent response from the distal to the proximal portion. Detailed investigation revealed a new structure in the venom-secreting epithelium, which is postulated to be an evolutionary adaptation to increasing gland volume. CSTX-1 was found to be synthesized and stored as a fully active toxin within complex units, composed of long interdigitating cells running perpendicular to the muscular sheath and extending into the central lumen of the gland. These venom-producing units were found in all sectors of the gland, including the transitional region between the main gland and the venom duct. The venom is liberated from the venom-producing units into the glandular lumen following the contraction of the surrounding muscle layer. Free nuclei or other cellular fragments, which would have provided evidence for a holocrine secretion process, were not found in the glandular lumen or in the crude venom obtained by electrical stimulation. The fine regulation of the spider's venom injection process is postulated to be the function of the bulbous ampulla, situated in the anterior third of the venom duct.     

Male Competition,Mating Success and Female Choice in a Seasonally Breeding Primate (Erythrocebus patas)

Mammals with restricted breeding seasons often show brief but intense bouts of male competition for mates and male reproductive success has been attributed to male competitive abilities, with the most aggressively successful males able to control access to fertile females, or with females choosing to mate with such males. We studied male competition, mating behaviour and female mate selection in patas monkeys, a primate with a restricted breeding period. We observed two habituated patas groups in Laikipia District, Kenya, during Jun.-Aug. 1983. During the study, one group had a single resident male while the other group had multiple adult males. Within the multimale group, experienced adult males were no more successful than the subadult male. The sole resident male had a significantly higher rate of fights won (p < 0.02) although he did not differ from the multimale group males in rate of aggression or initiation of fights. We found no significant differences in either mating success or female preference based on males' experience or residency. The rates at which males copulated with and were solicited by females were not significantly correlated. We found no evidence of stable dominance ranks among males in the multimale group and aggressive success was not significantly correlated with copulation rate for males in the multimale group. Subadult males were responsible for the majority of copulations observed during the final third of the breeding season. Our observations of this patas population showed a fluid number of males in groups, with the same groups able to shift rapidly from single to multimale structure. This fluidity may result from the large fluctuations in numbers of breeding-age males and females observed over 4 yr of studying this population.     

Structural and biochemical characterization of native and recombinant single insulin-like growth factor-binding domain protein (SIBD-1) from the Central American hunting spider Cupiennius salei (Ctenidae)

Cupiennius salei single insulin-like growth factor binding domain protein (SIBD-1) is an 8.6 kDa Cys-, Pro-, and Gly-rich protein, discovered in the hemocytes of the Central American hunting spider Cupiennius salei. SIBD-1 exhibits high sequence similarity to the N-terminal domain of the insulin-like growth factor-binding protein superfamily and has been reported to play an important role in the spider's immune system. Here, the recombinant expression and the elucidation of the three-dimensional structure of recombinant SIBD-1 and the characterization of the sugar moiety at Thr2 of native SIBD-1 is described in detail.     

Proprioceptors and sensory nerves in the legs of a spider,Cupiennius salei (Arachnida,Araneida)

Summary Retrograde CoS-impregnation was used to trace and map the course of sensory nerves and the distribution and innervation of the various proprioceptor types in all leg segments of Cupiennius salei, a Ctenid spider.1. Sensory nerve branches. In both the tibia and femur, axons of all proprioceptor types ascend in just two lateral nerves which do not merge with the main leg nerve until they reach the next proximal joint region. In the short segments — coxa, trochanter, patella, and tarsus — axons of the internal joint receptors often run separately from those of the other sensilla. Axons of the large lyriform slit sense organ at the dorsal metatarsus and of the trichobothria join with only a few hair axons and form their own nerve branches (Figs. 1, 2, 3).2. Proprioceptors. Each of the seven leg joints is supplied with at least one set of the well-known internal joint receptors, slit sensilla (single slits and lyriform organs), and long cuticular hairs. In addition, we found previously unnoticed hair plates on both sides of the coxa, near the prosoma/coxa joint; they are deflected by the articular membrane during joint movements (Fig. 4).3. Sensory cells and innervation. CoS-impregnation shows that each slit of the slit sense organs — be it a single slit or several slits in a lyriform organ — is innervated by two bipolar sensory cells (Fig. 6). We also confirm previous reports of multiple innervation in the internal joint receptors and in the long joint hairs and cuticular spines.Most of the ascending nerve branches run just beneath the cuticle for at least a short distance (Fig. 5); hence they are convenient sites for electrophysiological recordings of sensory activity even in freely walking spiders.     

圆尾银板蛛的雄性新发现（蜘蛛目：球蛛科）

记述产于我国海南、贵州和四川的圆尾银板蛛Thwaitesia glabicaucla Zhu,1998,其雄性系首次发现.     

Male Performance and Body Size Affect Female Re-Mating Occurrence in the Orb-Web Spider Leucauge mariana (Araneae, Tetragnathidae)

Females can affect male probabilities of paternity success through behavioural, morphological and/or physiological processes occurring during or after copulation. These processes under female-control include the acceptance or rejection of mating attempts by subsequent males. Leucauge mariana is an orb weaving spider that shows male mate guarding of penultimate females, male–male competition on female webs and copulatory plugs, suggesting a polyandric mating system. The aim of the present study was to ascertain whether male behaviour during courtship and copulation in L. mariana relate with female re-mating decisions. Forty-three virgin females were exposed to up to three males until they mated. In 24 cases, the copulatory plug was absent after mating and females were exposed the next day to up to three other males. Eighteen females accepted a second mating. Relatively larger females were more receptive to second matings and were more likely to copulate if the second male was smaller. Longer duration of female tapping and abdominal bobbing during courtship, and first copulations with less short insertions and more flubs, were associated with increased female acceptance to second matings. The results indicate cryptic female choice on male courtship and copulatory performance and suggest female-control over the determination of male mating success in this spider species.     

Phylogenetic analysis of the tropical wolf spider subfamily Cteninae (Arachnida,Araneae, Ctenidae)

A cladistic analysis based on parsimony was performed to test the monophyly of Cteninae. The data matrix comprises 72 terminal taxa scored for 88 characters from external morphology, female internal genitalia, and two behavioural characters. Cteninae, as currently delimited, is polyphyletic. The monoplyly of Cteninae requires the transfer of two Ctenus species to Enoploctenus (Acantheinae) and two Ctenus species to Asthenoctenus (Viridasiinae). Ctenus, the genus type, comprises approximately half of the described species of the family, and is polyphyletic as currently delimited. From the 32 Ctenus species added to this analysis, only 13 are recognized as Ctenus s.s.: (C. rectipes (C. pauloterrai (C. manauara, C. nigritus ((C. dubius, C. crulsi) ((C. amphora, C. minor) (C. medius, C. paubrasil (C. fernandae (C. ornatus, C. vehemens)))))))). The results suggest that at least eight new genera should be described to accommodate species misplaced in Ctenus. The result also refutes the monophyly of Amauropelma Raven, Stumkat & Gray, 2001, Celaetycheus Simon, 1897, Leptoctenus L. Koch, 1878, and Thoriosa Simon, 1910. The following taxonomic changes are proposed: Ctenus inazensis Strand, 1909 and Ctenus miserabilis Strand, 1916 are transferred to Enoploctenus; Ctenus tarsalis F.O. Pickard‐Cambridge, 1902 and Ctenus bulimus Strand, 1909 are transferred to Asthenoctenus Simon, 1897; Celaetycheus modestus Bryant, 1942 is transferred to Ohvida Polotow & Brescovit, 2009. © 2014 The Linnean Society of London