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Linda J. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Replacement of an inherited stretch receptor by a newly evolved stretch receptor in hippid sand crabs.
The Journal of comparative neurology, 1994Co-Authors: Dorothy H. Paul, Linda J. WilsonAbstract:Primary sensory neurons that are motoneuron-like in morphology and often nonspiking (transmit afferent signals as graded depolarizations) characterize an unusual type of stretch receptor in decapod crustaceans. Nonspiking and spiking receptors occur in similar positions at homologous joints in different species and have been presumed to be homologous, the spiking one considered "primitive". To better understand the evolutionary origin of these stretch receptors and why some are nonspiking, we examined the spiking Telson-uropod stretch receptors in the spiny sand crab Blepharipoda occidentalis (Albuneidae) and the squat lobster Munida quadrispina (Galatheidae) and compared them with the nonspking Telson-uropod stretch receptor of the mole sand crab Emerita analoga (Hippidae). The position, morphology and responses to stretch of the sensory neurons, and the ultrastructure of the elastic strand portion of the receptor are similar in M. quadrispina and B. occidentalis, except that in B. occidentalis the receptor muscles are substantially smaller and the extracellular matrix of the elastic receptor strand is both more extensive and more organized, reminiscent of the ultrastructure of E. analoga's nonspiking receptor. We conclude that the spiking Telson-uropod stretch receptors of albuneids and galatheids are homologous. The differences in the ultrastructure of their receptor strands imply that the efficiency of coupling receptor length change to deformation of the dendritic termini increases in the order M. quadrispina < B. occidentalis < E. analoga. The spiking and nonspiking Telson-uropod stretch receptors differ anatomically in three major respects that appear to preclude their homology. (1) The receptor strands are on opposite sides of a conserved muscle. (2) The sensory somata are in different regions of the sixth abdominal ganglion: a lateral cluster of somata for the spiking sensory neurons and two medial clusters, one anterior, one posterior, for the nonspiking sensory neurons. (3) The neuropil projections of the sensory neurons are different. We conclude that the hippid's nonspiking Telson-uropod stretch receptor evolved de novo and not by modification of the ancestral anomuran Telson-uropod stretch receptor (which Hippidae have lost).
Jan Mees - One of the best experts on this subject based on the ideXlab platform.
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Additions to the mysid fauna (Crustacea: Mysidacea) from coastal waters of Mozambique, with descriptions of two new species
Hydrobiologia, 2003Co-Authors: T.h. Wooldridge, Jan MeesAbstract:Two new species of mysid shrimps are described from shallow coastal waters of Northern Oman. Haplostylus quadrispinosus sp. nov. is primarily distinguished from allied species by the arrangement and size of lateral spines on the Telson. The form of the Telson and exopod of the 4th male pleopod characterize a second new species, Anisomysis arabica sp. nov. A third species Mysidopsis kenyana, was previously recorded only from East Africa and its presence in samples considerably extends its geographical distribution. Four mysid species are now documented from coastal waters of Oman.
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Doxomysis algoaensis, a new mysid species (Crustacea: Mysidacea) from Algoa Bay (South Africa)
Hydrobiologia, 2000Co-Authors: T.h. Wooldridge, Jan MeesAbstract:Doxomysis algoaensis sp.nov. is described from Algoa Bay, South Africa where it is common in nearshore marine waters just beyond the breaker line. D. algoaensis sp.nov. is morphologically similar to D. australiensis, but can readily be distinguished by the shape and armature of the Telson and the length of the exopod of the fourth male pleopod. The apical cleft is one fifth the Telson length in the former species and one third the length in D. australiensis. The Telson apex on each side of the cleft is also armed with five and four stout spines in the two species, respectively. In D. australiensis, the exopod of the fourth male pleopod is almost three times the length of the endopod; in D. algoaensis sp.nov., the exopod is only slightly longer than the endopod. Other distinctive features of D. algoaensis sp.nov. include the maxillary palp, which is only slightly broader than long and the greater number of spines on the endopod of the uropod.
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Aberrant individuals of Neomysis integer and other Mysidacea: intersexuality and variable Telson morphology
Netherlands Journal of Aquatic Ecology, 1995Co-Authors: Jan Mees, Nancy Fockedey, Ann Dewicke, Colin R. Janssen, Jean-claude SorbeAbstract:Intersexuality in the mysidNeomysis integer is described from samples collected in the Elbe (north Germany), Eems-Dollard (north Netherlands), Westerschelde (south-west Netherlands) and Gironde (southwest France) estuaries. Individuals which had an irregularly shaped or nearly symmetrically rounded Telson, rather than a typically truncated one, were also recorded from the four populations studied. A culture experiment with damaged specimens revealed that all types of abnormal Telson morphology found in the field can result from regeneration of damaged parts. It is concluded that both intersexuality and aberrant Telson morphology are widespread phenomena among estuarineN. integer populations. Both abnormalities seem to be rare in the other common mysid species in the study area: only one intersexualGastrosaccus spinifer and oneSchistomysis kervillei with an aberrant Telson were recorded.
Masaaki Murano - One of the best experts on this subject based on the ideXlab platform.
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Further Study on Australian Heteromysids (Crustacea: Mysidacea)
1998Co-Authors: Masaaki MuranoAbstract:Three new species of heteromysids are described. A new species, Heteromysis (Olivaemysis) maxima, collected from South Australia, is distinguished from allied species by a combination of characters in the shape of the rostrum, the spination on the carpopropodus of the thoracic endopod 3, and the numbers of spines on the uropodal endopod and the Telson. The second species, Heteromysoides nww sp. nov., from the Northern Territory, is identified by the Telson without apical cleft, the uropodal endopod without spines on the inner margin and the eyestalk with rounded anteromedial corner. The last species, Heteromysoides salwlensis sp. nov., captured from the Sahul Shelf, is different from other species of the genus in the shapes and armatures of the uropod and the Telson.
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MYSIDACEA FROM COASTAL WATERS OF IRIOMOTE ISLAND, RYUKYU ISLANDS, SOUTHWESTERN JAPAN, WITH DESCRIPTIONS OF THREE NEW SPECIES
Journal of Crustacean Biology, 1997Co-Authors: Kouki Fukuoka, Masaaki MuranoAbstract:ABSTRACT Fifteen mysid species, including three new species, are reported from Iriomote Island, Ryukyu Islands, Japan. A new species, Iiella iriomotensis, is distinguished from related species by the shapes of the rostrum and the Telson cleft, the number of spines arming the frontal margin of the labrum, and the endopod of the uropod being shorter than the exopod. Nipponomysis minuta, new species, closely resembles Nipponomysis imparis in respect to the fourth male pleopod, but is distinguished by the shorter Telson and the smaller number of spines on the lateral margin of the Telson and on the inner margin of the endopod of the uropod. Anisomysis hashizumei, new species, is distinguished from related species by a combination of characters found in the fourth male pleopod and the Telson. Haplostylus pusillus, which has been known only from the Indian Ocean, is reported from the Pacific Ocean for the first time. Four species, Siriella inornata, S. anomala, Anchialina zimmeri, and Pseudanchialina pusilla are new records from Japanese waters.
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MYSIDACEA FROM COASTAL WATERS OF IRIOMOTE ISLAND, RYUKYU ISLANDS, SOUTHWESTERN JAPAN, WITH DESCRIPTIONS OF
1997Co-Authors: Three New Species, Kouki Fukuoka, Masaaki MuranoAbstract:Fifteen mysid species, including three new species, are reported from Iriomote Island, Ryukyu Islands, Japan. A new species, Iiella iriomotensis, is distinguished from related species by the shapes of the rostrum and the Telson cleft, the number of spines arming the frontal margin of the labrum, and the endopod of the uropod being shorter than the exopod. Nipponomysis minuta, new species, closely resembles Nipponomysis imparis in respect to the fourth male pleopod, but is distinguished by the shorter Telson and the smaller number of spines on the lateral margin of the Telson and on the inner margin of the endopod of the uropod. Anisomysis hashizumei, new species, is distinguished from related species by a combination of characters found in the fourth male pleopod and the Telson. Haplostylus pusillus, which has been known only from the Indian Ocean, is reported from the Pacific Ocean for the first time. Four species, Siriella inornata, S. anomala, Anchialina zimmeri, and Pseudanchialina pusilla are new records from Japanese waters.
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Two New Species of the Genus Anisomysis (Crustacea: Mysidacea) from Northern Australia
1995Co-Authors: Masaaki MuranoAbstract:Nine species and subspecies of Anisomysis have been recorded from Australian waters to date. These are A. bipartoculata, A. gracilis, A. hispida, A.incisa, A. laticauda, A. mixta australis, A. mullini, A. pelewensis and A. robustispina. The present two new species, therefore, are the tenth and eleventh species of Anisomysis, and their occurrence is the first record from Northern Territory waters. Anisomysis spatulispina n. sp. is distinguished from other species of the genus by the shape and armature of the Telson. Anisomysis nana n. sp. is distinguished from allied species by having a rounded rostrum and the Telson with a deep, U-shaped cleft.
Dorothy H. Paul - One of the best experts on this subject based on the ideXlab platform.
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Replacement of an inherited stretch receptor by a newly evolved stretch receptor in hippid sand crabs.
The Journal of comparative neurology, 1994Co-Authors: Dorothy H. Paul, Linda J. WilsonAbstract:Primary sensory neurons that are motoneuron-like in morphology and often nonspiking (transmit afferent signals as graded depolarizations) characterize an unusual type of stretch receptor in decapod crustaceans. Nonspiking and spiking receptors occur in similar positions at homologous joints in different species and have been presumed to be homologous, the spiking one considered "primitive". To better understand the evolutionary origin of these stretch receptors and why some are nonspiking, we examined the spiking Telson-uropod stretch receptors in the spiny sand crab Blepharipoda occidentalis (Albuneidae) and the squat lobster Munida quadrispina (Galatheidae) and compared them with the nonspking Telson-uropod stretch receptor of the mole sand crab Emerita analoga (Hippidae). The position, morphology and responses to stretch of the sensory neurons, and the ultrastructure of the elastic strand portion of the receptor are similar in M. quadrispina and B. occidentalis, except that in B. occidentalis the receptor muscles are substantially smaller and the extracellular matrix of the elastic receptor strand is both more extensive and more organized, reminiscent of the ultrastructure of E. analoga's nonspiking receptor. We conclude that the spiking Telson-uropod stretch receptors of albuneids and galatheids are homologous. The differences in the ultrastructure of their receptor strands imply that the efficiency of coupling receptor length change to deformation of the dendritic termini increases in the order M. quadrispina < B. occidentalis < E. analoga. The spiking and nonspiking Telson-uropod stretch receptors differ anatomically in three major respects that appear to preclude their homology. (1) The receptor strands are on opposite sides of a conserved muscle. (2) The sensory somata are in different regions of the sixth abdominal ganglion: a lateral cluster of somata for the spiking sensory neurons and two medial clusters, one anterior, one posterior, for the nonspiking sensory neurons. (3) The neuropil projections of the sensory neurons are different. We conclude that the hippid's nonspiking Telson-uropod stretch receptor evolved de novo and not by modification of the ancestral anomuran Telson-uropod stretch receptor (which Hippidae have lost).
Jih-pai Lin - One of the best experts on this subject based on the ideXlab platform.
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Function and hydrostatics in the Telson of the Burgess Shale arthropod Burgessia
Biology letters, 2009Co-Authors: Jih-pai LinAbstract:Burgessia bella is a characteristic Burgess Shale arthropod (508Ma), but the unusual preservation of its Telson in both straight and bent modes leads to contradictory interpretations of its function. A reinvestigation of the fossil material, including burial attitudes, combined with a comparison with the decay sequence and mechanics of the Telson in living Limulus, demonstrates that the Telson of Burgessia was flexible in its relaxed state but could be stiffened in life. Evidence of fluid within the Telson indicates that this manoeuvrability was achieved by changes in hydrostatic pressure and muscular control. The dual mode in the Burgessia Telson is, to my knowledge, the first documented among fossil arthropods. It indicates that the requirement for a rigid Telson, which is resolved by a thick sclerotized cuticle in most arthropods, may first have been achieved by hydrostatic means.
