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Wolfgang Rössler - One of the best experts on this subject based on the ideXlab platform.
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johnston s organ and its central projections in cataglyphis desert ants
The Journal of Comparative Neurology, 2020Co-Authors: Robin Grob, Clara Tritscher, Kornelia Grubel, Christian Stigloher, Claudia Groh, Pauline N Fleischmann, Wolfgang RösslerAbstract:The Johnston's organ (JO) in the insect antenna is a multisensory organ involved in several navigational tasks including wind-compass orientation, flight control, graviception, and, possibly, magnetoreception. Here we investigate the three dimensional anatomy of the JO and its neuronal projections into the brain of the desert ant Cataglyphis, a marvelous long-distance navigator. The JO of C. nodus workers consists of 40 Scolopidia comprising three sensory neurons each. The numbers of Scolopidia slightly vary between different sexes (female/male) and castes (worker/queen). Individual Scolopidia attach to the intersegmental membrane between pedicel and flagellum of the antenna and line up in a ring-like organization. Three JO nerves project along the two antennal nerve branches into the brain. Anterograde double staining of the antennal afferents revealed that JO receptor neurons project to several distinct neuropils in the central brain. The T5 tract projects into the antennal mechanosensory and motor center (AMMC), while the T6 tract bypasses the AMMC via the saddle and forms collaterals terminating in the posterior slope (PS) (T6I), the ventral complex (T6II), and the ventrolateral protocerebrum (T6III). Double labeling of JO and ocellar afferents revealed that input from the JO and visual information from the ocelli converge in tight apposition in the PS. The general JO anatomy and its central projection patterns resemble situations in honeybees and Drosophila. The multisensory nature of the JO together with its projections to multisensory neuropils in the ant brain likely serves synchronization and calibration of different sensory modalities during the ontogeny of navigation in Cataglyphis. This article is protected by copyright. All rights reserved.
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Johnston’s Organ and its Central Projections in Cataglyphis Desert Ants
The Journal of comparative neurology, 2020Co-Authors: Robin Grob, Clara Tritscher, Kornelia Grubel, Christian Stigloher, Claudia Groh, Pauline N Fleischmann, Wolfgang RösslerAbstract:The Johnston's organ (JO) in the insect antenna is a multisensory organ involved in several navigational tasks including wind-compass orientation, flight control, graviception, and, possibly, magnetoreception. Here we investigate the three dimensional anatomy of the JO and its neuronal projections into the brain of the desert ant Cataglyphis, a marvelous long-distance navigator. The JO of C. nodus workers consists of 40 Scolopidia comprising three sensory neurons each. The numbers of Scolopidia slightly vary between different sexes (female/male) and castes (worker/queen). Individual Scolopidia attach to the intersegmental membrane between pedicel and flagellum of the antenna and line up in a ring-like organization. Three JO nerves project along the two antennal nerve branches into the brain. Anterograde double staining of the antennal afferents revealed that JO receptor neurons project to several distinct neuropils in the central brain. The T5 tract projects into the antennal mechanosensory and motor center (AMMC), while the T6 tract bypasses the AMMC via the saddle and forms collaterals terminating in the posterior slope (PS) (T6I), the ventral complex (T6II), and the ventrolateral protocerebrum (T6III). Double labeling of JO and ocellar afferents revealed that input from the JO and visual information from the ocelli converge in tight apposition in the PS. The general JO anatomy and its central projection patterns resemble situations in honeybees and Drosophila. The multisensory nature of the JO together with its projections to multisensory neuropils in the ant brain likely serves synchronization and calibration of different sensory modalities during the ontogeny of navigation in Cataglyphis. This article is protected by copyright. All rights reserved.
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Morphology of the tibial organs of acrididae: Comparison of subgenual and distal organs in fore‐, mid‐, and hindlegs of Schistocerca gregaria (Acrididae, Catantopinae) and Locusta migratoria (Acrididae, Oedipodinae)
Journal of morphology, 1995Co-Authors: Yuzhen Lin, Wolfgang Rössler, Klaus KalmringAbstract:The structure of the complex tibial organs in the fore-, mid-, and hindlegs of two grasshopper species, Schistocerca gregaria (Acrididae, Catantopinae) and Locusta migratoria (Acrididae, Oedipodinae), is described. In each leg the tibial organs consist of two scolopale organs: the subgenual organ and the distal organ. Both organs are located in the hemolymph channel. The subgenual organ has a sail-like structure, and its Scolopidia are oriented perpendicular to the long axis of the leg. The number of Scolopidia in the subgenual organs is lower in Locusta migratoria than in Schistocerca gregaria. The Scolopidia of the distal organ are clearly spearated from those of the subgenual organ and lie parallel with the long axis of the legs. They insert distally on an attachment plate that lies in the hemolymph channel. The subgenual organs and the distal organs are smaller in the hindlegs than in the fore- and midlegs, and this difference is especially pronounced in Locusta migratoria. The complex tibial organ of Locusta and Schistocerca is very similar in structure and cellular composition with that of Periplaneta (Blattidae). In tettigoniids and gryllids the distal organ is differentiated into an intermediate organ and the crista acoustica. © 1995 Wiley-Liss, Inc. © 1995 Wiley-Liss, Inc.
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Structure of atympanate tibial organs in legs of the cave-living ensifera, Troglophilus neglectus (Gryllacridoidea, Raphidophoridae).
Journal of morphology, 1995Co-Authors: S. Jeram, Wolfgang Rössler, A. Čokl, Klaus KalmringAbstract:Troglophilus neglectus (Gryllacridoidea, Raphidophoridae) is a nocturnal Ensifera which can be found in caves of Slovenia. The anatomy of the tibial organs in the fore-, mid-, and hindlegs, as well as the external morphology of the proximal fore-tibia and the prothoracic tracheal system, is described comparatively. In the prothorax and in the forelegs, no sound-conducting structures such as an acoustic trachea, enlarged spiracles, or tympana are developed. A group of 8-10 campaniform sensillae is located in the dorsal cuticle of the proximal tibia. In each leg, the tibial organ complex is built up by two scolopale organs, the subgenual organ and the intermediate organ; the structure and the number of Scolopidia is similar in each leg. No structure resembling the crista acoustica is found. The subgenual organ contains around 30 Scolopidia; the intermediate organ is subdivided into a proximal part containing 8-9 Scolopidia and a distal part with 5-6 Scolopidia. The two groups of Scolopidia are not directly connected to the tracheal system. The tibial organs in the forelegs are insensitive to airborne sound, and they appear to be more primitive compared to those found in members of the Tettigoniidae and the Gwllidae. The results indicate that the complex tibial organs in all legs of T. neglectus are primarily vibrosensitive. © 1995 Wiley-Liss, Inc.
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Comparison of song frequency and receptor tuning in two closely related bushcricket species.
Acta biologica Hungarica, 1995Co-Authors: Klaus Kalmring, Wolfgang Rössler, Martin Jatho, E. HoffmannAbstract:The songs and the structure and physiology of the auditory organs in the closely related bushcricket species Tettigonia viridissima and Tettigonia cantans were investigated comparatively using bioacoustical, histological and neurophysiological methods. The morphology of the crista acustica, the main auditory receptor organ, is very similar in the two species in respect to both the distribution of Scolopidia along the length axis of the crista and the dimensions of corresponding Scolopidia and attachment structures. The only obvious difference is that T. viridissima has one more scolopidium in the crista acustica and that the overall length of the crista is by about 50 microns larger than in T. cantans. In contrast, differences were found in the physiology of individual auditory receptor cells. Comparison of the threshold characteristics of all the receptor cells of the crista acustica in both species reveals a differential sensitivity of groups of auditory receptor cells at dominant frequencies of the song. In each species, the sensitivity of auditory receptor cells is method to the energy spectrum of the song. These differences in the physiology can partly be explained by differences in transmission characteristics of the acoustic trachea.
Klaus Kalmring - One of the best experts on this subject based on the ideXlab platform.
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The auditory-vibratory system of the bushcricket Polysarcus denticauda (Phaneropterinae, Tettigoniidae). I. Morphology of the complex tibial organs.
Hearing research, 1997Co-Authors: Thomas Sickmann, Klaus Kalmring, Antje WillerAbstract:Abstract The structure of the complex tibial organs in the fore-, mid-, and hindlegs of the bushcricket Polysarcus denticauda (Tettigoniidae, Phaneropterinae) is described comparatively. As is common for bushcrickets, in each leg the tibial organs consist of the subgenual and intermediate organs and the crista acustica. Only in the forelegs are sound-transmitting structures present. They consist of the spiracle, acoustic trachea, and two tympana; the latter are not protected by tympanal covers. The tympana in P. denticauda are extremely thick, not only bordering the two tracheal branches to the outside but also forming the outer wall of the hemolymph channel. The morphology of the tracheae in the mid- and hindlegs is significantly different, causing structural differences, especially in dimensions of the hemolymph channel. The number of Scolopidia of the crista acustica of the foreleg is extremely high for a bushcricket. Approximately 50 receptor cells were found, about half of them being located in the distal quarter of the long axis of this organ. Some of the receptors are positioned in parallel on the dorsal wall of the anterior tracheal branch. The number, morphology and dimensions of the Scolopidia within the crista acustica of the mid- and hindlegs differ significantly from those of the forelegs, decreasing in both legs to eight and seven receptor cells, respectively. Although the dimensions of the subgenual and intermediate organs are considerably larger in the mid- and hindlegs, the number of receptor cells is approximately the same in the different legs, being somewhat higher in both receptor organs than in those of many other bushcricket species studied previously.
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Morphology of the tibial organs of acrididae: Comparison of subgenual and distal organs in fore‐, mid‐, and hindlegs of Schistocerca gregaria (Acrididae, Catantopinae) and Locusta migratoria (Acrididae, Oedipodinae)
Journal of morphology, 1995Co-Authors: Yuzhen Lin, Wolfgang Rössler, Klaus KalmringAbstract:The structure of the complex tibial organs in the fore-, mid-, and hindlegs of two grasshopper species, Schistocerca gregaria (Acrididae, Catantopinae) and Locusta migratoria (Acrididae, Oedipodinae), is described. In each leg the tibial organs consist of two scolopale organs: the subgenual organ and the distal organ. Both organs are located in the hemolymph channel. The subgenual organ has a sail-like structure, and its Scolopidia are oriented perpendicular to the long axis of the leg. The number of Scolopidia in the subgenual organs is lower in Locusta migratoria than in Schistocerca gregaria. The Scolopidia of the distal organ are clearly spearated from those of the subgenual organ and lie parallel with the long axis of the legs. They insert distally on an attachment plate that lies in the hemolymph channel. The subgenual organs and the distal organs are smaller in the hindlegs than in the fore- and midlegs, and this difference is especially pronounced in Locusta migratoria. The complex tibial organ of Locusta and Schistocerca is very similar in structure and cellular composition with that of Periplaneta (Blattidae). In tettigoniids and gryllids the distal organ is differentiated into an intermediate organ and the crista acoustica. © 1995 Wiley-Liss, Inc. © 1995 Wiley-Liss, Inc.
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Structure of atympanate tibial organs in legs of the cave-living ensifera, Troglophilus neglectus (Gryllacridoidea, Raphidophoridae).
Journal of morphology, 1995Co-Authors: S. Jeram, Wolfgang Rössler, A. Čokl, Klaus KalmringAbstract:Troglophilus neglectus (Gryllacridoidea, Raphidophoridae) is a nocturnal Ensifera which can be found in caves of Slovenia. The anatomy of the tibial organs in the fore-, mid-, and hindlegs, as well as the external morphology of the proximal fore-tibia and the prothoracic tracheal system, is described comparatively. In the prothorax and in the forelegs, no sound-conducting structures such as an acoustic trachea, enlarged spiracles, or tympana are developed. A group of 8-10 campaniform sensillae is located in the dorsal cuticle of the proximal tibia. In each leg, the tibial organ complex is built up by two scolopale organs, the subgenual organ and the intermediate organ; the structure and the number of Scolopidia is similar in each leg. No structure resembling the crista acoustica is found. The subgenual organ contains around 30 Scolopidia; the intermediate organ is subdivided into a proximal part containing 8-9 Scolopidia and a distal part with 5-6 Scolopidia. The two groups of Scolopidia are not directly connected to the tracheal system. The tibial organs in the forelegs are insensitive to airborne sound, and they appear to be more primitive compared to those found in members of the Tettigoniidae and the Gwllidae. The results indicate that the complex tibial organs in all legs of T. neglectus are primarily vibrosensitive. © 1995 Wiley-Liss, Inc.
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Comparison of song frequency and receptor tuning in two closely related bushcricket species.
Acta biologica Hungarica, 1995Co-Authors: Klaus Kalmring, Wolfgang Rössler, Martin Jatho, E. HoffmannAbstract:The songs and the structure and physiology of the auditory organs in the closely related bushcricket species Tettigonia viridissima and Tettigonia cantans were investigated comparatively using bioacoustical, histological and neurophysiological methods. The morphology of the crista acustica, the main auditory receptor organ, is very similar in the two species in respect to both the distribution of Scolopidia along the length axis of the crista and the dimensions of corresponding Scolopidia and attachment structures. The only obvious difference is that T. viridissima has one more scolopidium in the crista acustica and that the overall length of the crista is by about 50 microns larger than in T. cantans. In contrast, differences were found in the physiology of individual auditory receptor cells. Comparison of the threshold characteristics of all the receptor cells of the crista acustica in both species reveals a differential sensitivity of groups of auditory receptor cells at dominant frequencies of the song. In each species, the sensitivity of auditory receptor cells is method to the energy spectrum of the song. These differences in the physiology can partly be explained by differences in transmission characteristics of the acoustic trachea.
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Complex tibial organs in fore-, mid-, and hindlegs of the bushcricket Gampsocleis gratiosa (Tettigoniidae): Comparison of morphology of the organs
Journal of morphology, 1994Co-Authors: Yuzhen Lin, Wolfgang Rössler, Klaus KalmringAbstract:The structure of the complex tibial organs in the fore-, mid-, and hindlegs of the East Asian bushcricket Gampsocleis gratiosa (Tettigoniidae, Decticinae) is described comparatively. In each leg the tibial organs consist of three scolopale organs: the subgenual organ, the intermediate organ, and the crista acoustica. Only in the forelegs are the tibial organs differentiated as tympanal organs, and sound transmitting structures (acoustic trachea, tympana, and tympanal covers) are present. The morphology of the tracheae in the mid- and hindlegs is significantly different from that found in the forelegs. The number of Scolopidia in the subgenual organ is highest in the midleg and lowest in the foreleg; in the intermediate organ the number is also highest in the midleg, and the fore- and hindleg contain 40% fewer Scolopidia. In the crista acoustica, the number of Scolopidia decreases from, the fore- to the mid- and hindlegs. The morphology and the dimensions of the Scolopidia and the attachment structures within the crista acoustica of the mid- and hindlegs differ strongly from those in the foreleg. The results indicate that, in addition to the presence of a sound transmitting system, the specific differentiations within the crista acoustica are important for the high auditory sensitivity of the tibial organs in the forelegs. © 1994 Wiley-Liss, Inc.
Johannes Strauß - One of the best experts on this subject based on the ideXlab platform.
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Low-frequency vibration transmission and mechanosensory detection in the legs of cave crickets
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2019Co-Authors: Nataša Stritih-peljhan, Peter T. Rühr, Barbara Buh, Johannes StraußAbstract:Abstract Vibrational communication is common in insects and often includes signals with prominent frequency components below 200 Hz, but the sensory adaptations for their detection are scarcely investigated. We performed an integrative study of the subgenual organ complex in Troglophilus cave crickets (Orthoptera: Rhaphidophoridae), a mechanosensory system of three Scolopidial organs in the proximal tibia, for mechanical, anatomical and physiological aspects revealing matches to low frequency vibration detection. Microcomputed tomography shows that a part of the subgenual organ sensilla and especially the accessory organ posteriorly in this complex are placed closely underneath the cuticle, a position suited to evoke responses to low-frequency vibration via changes in the cuticular strain. Laser-Doppler vibrometry shows that in a narrow low-frequency range the posterior tibial surface reacts stronger to low frequency sinusoidal vibrations than the anterior tibial surface. This finding suggests that the posterior location of sensilla in tight connection to the cuticle, especially in the accessory organ, is adapted to improve detectability of low-frequency vibration signals. By electrophysiological recordings we identify a Scolopidial receptor type tuned to 50–300 Hz vibrations, which projects into the central mechanosensory region specialised for processing low-frequency vibratory inputs, and most likely originates from the accessory organ or the posterior subgenual organ. Our findings contribute to understanding of the mechanical and neuronal basis of low-frequency vibration detection in insect legs and their highly differentiated sensory systems.
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The Scolopidial accessory organs and Nebenorgans in orthopteroid insects: Comparative neuroanatomy, mechanosensory function, and evolutionary origin
Arthropod Structure & Development, 2017Co-Authors: Johannes StraußAbstract:Scolopidial sensilla in insects often form large sensory organs involved in proprioception or exteroception. Here the knowledge on Nebenorgans and accessory organs, two organs consisting of Scolopidial sensory cells, is summarised. These organs are present in some insects which are model organisms for the physiology of mechanosensory systems (cockroaches and tettigoniids). Recent comparative studies documented the accessory organ in several taxa of Orthoptera (including tettigoniids, cave crickets, Jerusalem crickets) and the Nebenorgan in related insects (Mantophasmatodea). The accessory organ or Nebenorgan is usually a small organ of 8-15 sensilla located in the posterior leg tibia of all leg pairs. The physiological properties of the accessory organs and Nebenorgans are so far largely unknown. Taking together neuroanatomical and electrophysiological data from disparate taxa, there is considerable evidence that the accessory organ and Nebenorgan are vibrosensitive. They thus complement the larger vibrosensitive subgenual organ in the tibia. This review summarises the comparative studies of these sensory organs, in particular the arguments and criteria for the homology of the accessory organ and Nebenorgan among orthopteroid insects. Different scenarios of repeated evolutionary origins or losses of these sensory organs are discussed. Neuroanatomy allows to distinguish individual sensory organs for analysis of sensory physiology, and to infer scenarios of sensory evolution.
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The Scolopidial accessory organ in the Jerusalem cricket (Orthoptera: Stenopelmatidae)
Arthropod Structure & Development, 2017Co-Authors: Johannes StraußAbstract:Abstract Multiple mechanosensory organs form the subgenual organ complex in orthopteroid insects, located in the proximal tibia. In several Ensifera (Orthoptera), a small chordotonal organ, the so-called accessory organ, is the most posterior part of this sensory complex. In order to document the presence of this accessory organ among the Ensifera, the chordotonal sensilla and their innervation in the posterior tibia of two species of Jerusalem crickets (Stenopelmatidae: Stenopelmatus ) is described. The sensory structures were stained by axonal tracing. Scolopidial sensilla occur in the posterior subgenual organ and the accessory organ in all leg pairs. The accessory organ contains 10–17 Scolopidial sensilla. Both groups of sensilla are commonly spatially separated. However, in few cases neuronal fibres occurred between both organs. The two sensillum groups are considered as separate organs by the general spatial separation and innervation by different nerve branches. A functional role for mechanoreception is considered: since the accessory organ is located closely under the cuticle, sensilla may be suited to detect vibrations transferred over the leg's surface. This study extends the known taxa with an accessory organ, which occurs in several taxa of Ensifera. Comparative neuroanatomy thus suggests that the accessory organ may be conserved at least in Tettigoniidea.
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How many mechanosensory organs in the bushcricket leg? Neuroanatomy of the Scolopidial accessory organ in Tettigoniidae (Insecta: Orthoptera)
Arthropod structure & development, 2015Co-Authors: Johannes Strauß, Anja S. Riesterer, Reinhard Lakes-harlanAbstract:The subgenual organ and associated Scolopidial organs are well studied in Orthoptera and related taxa. In some insects, a small accessory organ or Nebenorgan is described posterior to the subgenual organ. In Tettigoniidae (Ensifera), the accessory organ has only been noted in one species though tibial sensory organs are well studied for neuroanatomy and physiology. Here, we use axonal tracing to analyse the posterior subgenual organ innervated by the main motor nerve. Investigating seven species from different groups of Tettigoniidae, we describe a small group of Scolopidial sensilla (5-9 sensory neurons) which has features characteristic of the accessory organ: posterior tibial position, innervation by the main leg nerve rather than by the tympanal nerve, orientation of dendrites in proximal or ventro-proximal direction in the leg, and commonly association with a single campaniform sensillum. The neuroanatomy is highly similar between leg pairs. We show differences in the innervation in two species of the genus Poecilimon as compared to the other species. In Poecilimon, the sensilla of the accessory organ are innervated by one nerve branch together with the subgenual organ. The results suggest that the accessory organ is part of the sensory bauplan in the leg of Tettigoniidae and probably Ensifera.
Reinhard Lakes-harlan - One of the best experts on this subject based on the ideXlab platform.
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How many mechanosensory organs in the bushcricket leg? Neuroanatomy of the Scolopidial accessory organ in Tettigoniidae (Insecta: Orthoptera)
Arthropod structure & development, 2015Co-Authors: Johannes Strauß, Anja S. Riesterer, Reinhard Lakes-harlanAbstract:The subgenual organ and associated Scolopidial organs are well studied in Orthoptera and related taxa. In some insects, a small accessory organ or Nebenorgan is described posterior to the subgenual organ. In Tettigoniidae (Ensifera), the accessory organ has only been noted in one species though tibial sensory organs are well studied for neuroanatomy and physiology. Here, we use axonal tracing to analyse the posterior subgenual organ innervated by the main motor nerve. Investigating seven species from different groups of Tettigoniidae, we describe a small group of Scolopidial sensilla (5-9 sensory neurons) which has features characteristic of the accessory organ: posterior tibial position, innervation by the main leg nerve rather than by the tympanal nerve, orientation of dendrites in proximal or ventro-proximal direction in the leg, and commonly association with a single campaniform sensillum. The neuroanatomy is highly similar between leg pairs. We show differences in the innervation in two species of the genus Poecilimon as compared to the other species. In Poecilimon, the sensilla of the accessory organ are innervated by one nerve branch together with the subgenual organ. The results suggest that the accessory organ is part of the sensory bauplan in the leg of Tettigoniidae and probably Ensifera.
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Comparison of auditory sense organs in parasitoid Tachinidae (Diptera) hosted by Tettigoniidae (Orthoptera) and homologous structures in a non-hearing Phoridae (Diptera)
Zoomorphology, 2007Co-Authors: Reinhard Lakes-harlan, Kirsten Jacobs, Geoff R. AllenAbstract:The dipteran parasitoids Therobia leonidei and Homotrixa alleni (Tachinidae) use acoustic cues to locate their calling tettigoniid (Ensifera, Orthoptera) hosts. The sexually dimorphic tympanal organs of both fly species are located at the prosternum. For comparison a homologous chordotonal organ in the non-hearing fly Phormia regina , Meigen (Phoridae) is also described. The Scolopidial sense organs of the ears have approximately 180 sensory cells in Th. leonidei and 250 cells in H. alleni. Interspecific analysis indicates that the cell number and arrangement might be genus specific in Tachinidae. The mononematic Scolopidia, each with one sensory cell, are of different sizes and insert at the tympanal membrane. Large Scolopidial units (diameter of sensory cells up to 50 μm) extend longitudinally from the centre of the sensory organ towards the ligament, whereas small units (sensory cell diameter up to 10 μm) are arranged sequentially within the sensory organ. This arrangement is discussed to be a possible basis for frequency discrimination. The ultrastructure of the Scolopidia is similar in the hearing and non-hearing flies. In both groups, the majority of scolopales has a diameter from 2 to 2.9 μm, although hearing species have additionally wider scolopales. The homologous chordotonal organ of Ph. regina consists of approximately 55 sensory cells of uniform direction. The data are discussed in comparison to the ears of other Diptera.
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CONVERGENT EVOLUTION OF INSECT HEARING ORGANS FROM A PREADAPTIVE STRUCTURE
Proceedings of The Royal Society B: Biological Sciences, 1999Co-Authors: Reinhard Lakes-harlan, Heiko Stölting, Andreas StumpnerAbstract:Flies of the taxon Emblemasomatini (Sarcophagidae: Diptera) independently evolved an ear with the same anatomy and location as the Ormiini (Tachinidae: Diptera). Both ears represent a first case of convergent evolution of homologous insect ears, which raises the question for a preadaptation. Physiological and anatomical data indicate a preadaptive-sound-insensitive, but vibration-sensitive Scolopidial chordotonal organ in non-hearing flies. As selective pressure for the evolutionary transformation from a vibration receiver into a sound receiver, fast and precise cues for the localization and detection of the sound producing hosts can be presumed.
Takashi Sugawara - One of the best experts on this subject based on the ideXlab platform.
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Chordotonal sensilla embedded in the epidermis of the soft integument of the cricket, Teleogryllus commodus
Cell and Tissue Research, 1996Co-Authors: Takashi SugawaraAbstract:More than 50 chordotonal sensilla, or Scolopidia, embedded entirely in the integument were found in each side of the genital chamber wall in the female cricket, Teleogryllus commodus . Their cell bodies lie among the epidermal cells, and the tips of their dendrites terminate in the cuticle. About half of them contain two sensory cells (two-cell scolopidium), the others only one (one-cell scolopidium). The sensory cell in the one-cell scolopidium is the type-1 cell. In the two-cell scolopidium one is type-1 and the other type-2. Regardless of the number of sensory cells, they are all amphinematic. In the two-cell scolopidium only the type-2 dendrite, rich in microtubules, penetrates into the cuticle, bifurcates and terminates in the tube enclosed by an attachment cell; the type-1 never extends into the cuticle. On the other hand, the type-1 cell in the one-cell scolopidium projects its apex into the cuticle. The unique topography and structure of these Scolopidia lead to the following hypothesis about the phylogenetic relationship between the Scolopidia and other kinds of sensilla: the type-1 Scolopidial sensory cell buried in the integument may be the original model, which through the loss of the long regular axoneme has given rise to type-2 cells. Modification of the apical region, the tubular body or ramification, may have lead to the cuticular sensilla corresponding to the development of the cuticular apparatus, and the Scolopidia may have been withdrawn into the body cavity to form ordinary chordotonal organs.