Central projections of cheliceral mechanoreceptors in the spider Cupiennius salei (Arachnida,Araneae)

Central projections of lyriform organs and tactile hairs on the chelicerae of the wandering spider Cupiennius salei were traced using anterograde cobalt fills. Different fibers arising from both mechanoreceptor types arborize in the cheliceral ganglia, which are part of the tritocerebrum, and in sensory longitudinal tracts in the center of the suboesophageal nerve mass together with afferent fibers arising from mechanoreceptors on the walking legs and the pedipalps. This convergence of sensory projections in the sensory longitudinal tracts might provide the anatomical basis for the coordination of the movements of different extremities during prey capture and feeding. The findings also support the hypothesis that the tritocerebrum originally was a preoral ganglion in spiders. © 1993 Wiley-Liss, Inc.     

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.     

Neuroarchitecture of the arcuate body in the brain of the spider Cupiennius salei (Araneae, Chelicerata) revealed by allatostatin-, proctolin-, and CCAP-immunocytochemistry and its evolutionary implications

Here we describe the neuronal organization of the arcuate body in the brain of the wandering spider Cupiennius salei. The internal anatomy of this major brain center is analyzed in detail based on allatostatin-, proctolin-, and crustacean cardioactive peptide (CCAP)-immunohistochemistry. Prominent neuronal features are demonstrated in graphic reconstructions. The stainings revealed that the neuroarchitecture of the arcuate body is characterized by several distinct layers some of which comprise nerve terminals that are organized in columnar, palisade-like arrays. The anatomy of the spider's arcuate body exhibits similarities as well as differences when compared to the central complex in the protocerebrum of the Tetraconata. Arguments for and against a possible homology of the arcuate body of the Chelicerata and the central complex of the Tetraconata and their consequences for the understanding of arthropod brain evolution are discussed.     

Central nervous projection patterns of trichobothria and other cuticular sensilla in the wandering spider Cupiennius salei (Arachnida,Araneae)

Summary Central projections of mechano-and chemoreceptors on the legs and pedipalps of the wandering spider Cupiennius salei were traced by anterograde cobalt fills. The primary afferent fibres from trichobothria, tactile hairs, lyriform organs and contact chemoreceptive hairs enter the leg ganglia and pedipalpal ganglia ventrally. On their way through these ganglia there is very little arborization. The main areas of arborization are in the sensory longitudinal tracts in the suboesophageal nervous mass. The central projections of all mechano-and chemoreceptors examined show somatotopic organization. Sensilla located proximally on the legs are represented in dorsally located sensory longitudinal tracts, whereas those located on distal leg segments enter more ventral tracts. The afferent fibres of receptors of identifical modality on a specific segment of all legs and of the pedipalps overlap in the same tracts. No indication for a tonotopic arrangement of the trichobothrial afferences was found, which might have been associated with the mechanical frequency tuning of the trichobothria known from other experiments. The convergence of the projections of different types of receptors in the sensory longitudinal tracts is considered to be an anatomical basis for their functional interaction in behaviour. Both the convergence of the projections of receptors from the same segment of different legs and the somatotopy are connectivity patterns possibly associated with the orientation of the spiders towards mechanical or chemical cues.     

Zum feinbau der cuticula von Limulus polyphemus L. (Chelicerata,Xiphosura)

The surface structure of the fracture in the exuvia of Limulus caused by the shedding of the exoskeleton is compared with the fine-structure of experimentally induced fractures using the electron microscope, Stereoscan.     

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.     

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.     

Die Cheliceren der Araneae,Amblypygi und Uropygi mit den Skleriten,den Plagulae (Chelicerata,Arachnomorpha)

Zusammenfassung 1. Die Arachnomorpha — Uropygi, Amblypygi, Araneae — besitzen in den Cheliceren ein oder zwei Sklerite an der Basis der Klaue, die Plagula ventralis und die Plagula dorsalis. Diese sind Bildungen der Haut und werden mit der Exuvie abgeworfen.2. Die Plagula ventralis ist im allgemeinen ein plattenförmiger oder stäbchenförmiger Sklerit. Proximal setzen an ihr die Beugemuskeln für die Klaue an. Distal ist sie durch ein biegsames Stück mit der Klaue verbunden. Da die Plagula ventralis vor dem Gelenk der Klaue ansetzt, verlängert sie den Hebelarm für die Beugemuskeln.3. Die Plagula ventralis ist im allgemeinen einfach, sie ist weiter entwickelt bei den Mygalomorphae der Araneae. Außen ist sie von einer dünnen Schicht Epicuticula begrenzt, darunter folgen dickere Schichten von Exo- und Mesocuticula. Der biegsame Teil am Ansatz der Klaue besteht nur aus Mesocuticula unter der dünnen Epicuticula.4. Die Plagula dorsalis findet sich nur bei Mygalomorphae der Araneae. Nur die Masteriinae besitzen sie nicht. Die Plagula dorsalis liegt als ein schmales Band quer vor der Basis der Klaue im dorsalen Fenster. Sie ist an drei Stellen verdickt und hier von feinen Kanälen durchzogen. Proximal und distal setzen die Sehnen der Streckmuskeln für die Klaue an. Eine besondere Funktion konnte nicht ermittelt werden.5. Die Nahrungsaufnahme, Kauen oder Saugen, ist an der Struktur der Cheliceren zu erkennen. Kauer besitzen zwei Reihen von Zähnen, manchmal in großer Anzahl. An der Basis des Grundgliedes befindet sich außen ein großer Condylus als Führungsschiene. Bei den Saugern ist die Anzahl der Zähne manchmal bis auf einen reduziert. Der Condylus an der Basis des Grundgliedes fehlt oder ist nur als Vestigium vorhanden.6. Die Plagula ventralis ist eine Autapomorphie des Taxon Arachnomorpha. Die Plagula dorsalis ist eine Autapomorphie der Mygalomorphae innerhalb der Araneae.

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The plagulae, sclerites at the base of the chelicerae of Araneae, Amblypygi, and Uropygi (Chelicerata, Arachnomorpha)

Summary 1. The Arachnomorpha (Uropygi, Amblypygi, Araneae) have one or two sclerites at the base of the fangs of their chelicerae, here called plagula ventralis and plagula dorsalis. These sclerites are part of the exoskeleton and are thus also visible in exuviae.2. Generally, the plagula ventralis is a plate- or rod-shaped sclerite, with the fang flexor muscles attached at its proximal end. Distally it is connected to the fang by a flexible part. Being attached distad of the fang articulation, the plagula ventralis extends the leverage of the flexor muscles. The plagula ventralis is simple in most Arachnomorpha, but in Mygalomorphae (Araneae) it is more complicated. Externally there is a thin epicuticular layer, with thicker layers of exo- and mesocuticula underneath. The flexible part at its contact with the fang consists exclusively of mesocuticula.3. The plagula dorsalis is found only in Mygalomorphae. It forms a narrow strip across the dorsal base of the fang. Three sections of it are thicker and passed by thin channels, with tendons of the fang extensor muscles attached to their proximal and distal ends. The function of the plagula dorsalis remains uncertain.4. The presence of a plagula ventralis is an autapomorphy of the Arachnomorpha, whereas the plagulae dorsalis are hypothesized to be an autapomorphy of the Mygalomorphae within the Araneae.5. Different modes of food ingestion (chewing and sucking) may be recognized by different cheliceral structures. Chewers have numerous teeth; outside at the base of the paturon a big condylus acts as a leading strip. Those that pump insects out have fewer teeth, in several cases only one tooth. The condylus at the base of the paturon is missing or vestigial.

     

Central nervous projections of mechanoreceptors in the spider Cupiennius salei Keys.

Summary The basic organization of sensory projections in the suboesophageal central nervous system of a spider (Cupiennius salei Keys.) was analyzed with anterograde cobalt fills and a modified Golgi rapid method. The projections of three lyriform slit sense organs and of tactile hairs located proximally on the legs are described and related to central nerve tracts. There are five main longitudinal sensory tracts in the central region of the suboesophageal nervous mass arranged one above the other. Whereas the three dorsal ones contain fibers from the lyriform organs, the two ventral ones contain axons from the hair receptors. Axons from all three lyriform organs have typical shapes and widely arborizing ipsilateral intersegmental branches and a few contralateral ones. The terminal branches of the afferent projections from identical lyriform organs on each leg form characteristic longitudinal pathways, typical of each organ: U-shaped, O-shaped, or two parallel bundles. The terminations of the hair sensilla are ipsilateral and intersegmental. Two large bilaterally arranged longitudinal sensory association tracts receive inputs from all legs including the dense arborizations from tactile hairs, lyriform organs, and other sense organs. These tracts may serve as important integrating neuropils of the suboesophageal central nervous system.     

Some comments on the hydrostatic system of spiders (Chelicerata,Araneae)

An anatomical study of five spider types has shown that the musculi laterales of the prosoma, together with the subcuticular muscle sheet of the opisthosoma, may be jointly responsible for generating the internal hydrostatic pressures which control the leg extension mechanism.     

Female sex pheromone of a wandering spider (Cupiennius salei): identification and sensory reception

Females of the wandering spider Cupiennius salei attach a sex pheromone to their dragline. Males encountering the female dragline examine the silk thread with their pedipalps and then typically initiate reciprocal vibratory courtship with the sexual partner. The female pheromone was identified as (S)-1,1'-dimethyl citrate. The male pheromone receptive sensory cells are located in tip pore sensilla and respond to touching the sensillum tip with female silk or pieces of filter paper containing the synthetic pheromone.     

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.     

The hydraulic interaction between prosoma and opisthosoma in Amaurobius ferox (Chelicerata,Araneae)

Summary Experiments are described which demonstrate that blood moves from the prosoma into the opisthosoma in Amaurobius ferox when the spider is held on a plasticine block and is stimulated with a small brush. This movement of blood is also seen during bouts of struggling when the spider is trying to free itself. The return flow of blood from the opisthosoma is to a large extent due to the pumping action of the heart.It is proposed that the locomotory exhaustion shown by artificially stimulated spiders is due to this loss of blood from the prosoma which leads not only to hydraulic insufficiency, but also to a lack of oxygen through interruption of the normal blood flow.     

Neuroanatomy of the central nervous system of the wandering spider,Cupiennius salei (Arachnida,Araneida)

Summary In Cupiennius salei (Ctenidae), as in other spiders, the central nervous system is divided into the supraoesophageal ganglion or brain and the suboesophageal ganglia (Fig. 1). The two masses are interconnected by oesophageal connectives. The brain gives off four pairs of optic and one pair of cheliceral nerves. From the suboesophageal ganglia arise a pair of pedipalpal, four pairs of leg, and several pairs of opisthosomal nerves (Fig. 2). 1. Cell types. In the brain a total of 50900 cells were counted, in the suboesophageal ganglia 49000. They are all monopolar cells, found in the ganglion periphery and may be classified into four types: (a) Small globuli cells (nuclear diameter 6–7 m) forming a pair of compact masses in the protocerebrum (Fig. 10b); (b) Small and numerous cells (cell diameter 12–20 m) with processes forming the bulk of the neuropil in the brain and suboesophageal ganglia; (c) Neurosecretory cells (cell diameter ca. 45 m) in the brain and suboesophageal ganglia; (d) Large motor and interneurons (cell daimeter 40–112 m), mostly in the suboesophageal ganglia (Figs. 10a and c). 2. Suboesophageal mass. The cell bodies form a sheet of one to several cell layers on the ventral side of each ganglion and are arranged in groups. Three such groups were identified as motor neurons, four as interneurons. At the dorsal, dorso-lateral, and mid-central parts of the ganglion there are no cell somata. The fibre bundles arising from them form identifiable transverse commissural pathways (Fig. 9b). They form the fibrous mass in the central part of the suboesophageal mass.Neuropil is well-formed in association with the sensory terminations of all major nerves (Fig. 9a). As these proceed centrally they break up into five major sensory tracts forming five layers one above the other. There are six pairs of additional major longitudinal tracts arranged at different levels dorsoventrally (Fig. 8). They ascend into the brain through the oesophageal connectives and terminate mostly in the mushroom bodies and partly in the central body. 3. Protocerebrum. Fine processes of the globuli cells form the most important neuropil mass in the fibrous core, called the mushroom bodies. These consist of well developed glomeruli, hafts, and bridge which are interconnected with the optic masses of the lateral eyes and most fibre tracts from the brain and suboesophageal mass (Fig. 7). The median eye nerves form a small optic lamella and optic ganglia, connected to the central body through an optic tract. Each posterior median and posterior lateral eye nerve ends in large optic lamellae (Fig. 13a). These are connected through chiasmata to a large optic mass where fibres from globuli cells form conspicuous glomeruli. There are 10–12 large fibres (diameter 9 m) of unknown origin on each side, terminating in the optic lambella of the posterior lateral eye.The central body, another neuropil mass (Fig. 13b) in the protocerebrum, is well developed in Cupiennius and located transversely in its postero-dorsal region (Fig. 10d). It consists of two layers and is interconnected with optic masses of the median and lateral eyes through optic tracts. Fibre tracts from the brain and suboesophageal mass join the central body.