1. Gastrotricha, Cycloneuralia and Gnathifera: General History and Phylogeny

Schmidt‐Rhaesa, Andreas

doi:10.1515/9783110272536.1

Cited by 31 publications

(32 citation statements)

References 36 publications

(46 reference statements)

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“…Characters synapomorphic for Ecdysozoa or Bilateria were grouped as ‘plesiomorphic’. As a phylum, Priapulida are characterized by an invaginable proboscis (introvert) bearing multiple longitudinal rows of scalids and pentagons of cuspidate teeth644. Some other characters that are general for Priapulida vary within the group and were treated as plesiomorphic (i.e.…”

Section: Methodsmentioning

confidence: 99%

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Preservation and phylogeny of Cambrian ecdysozoans tested by experimental decay of Priapulus

Sansom

2016

Sci Rep

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The exceptionally preserved Cambrian fossil record provides unique insight into the early evolutionary history of animals. Understanding of the mechanisms of exceptional soft tissue preservation frames all interpretations of the fauna and its evolutionary significance. This is especially true for recent interpretations of preserved nervous tissues in fossil ecdysozoans. However, models of soft tissue preservation lack empirical support from actualistic studies. Here experimental decay of the priapulid Priapulus reveal consistent bias towards rapid loss of internal non-cuticular anatomy compared with recalcitrant cuticular anatomy. This is consistent with models of Burgess Shale-type preservation and indicates that internal tissues are unlikely to be preserved with fidelity if organically preserved. This pattern, along with extreme body margin distortion, is consistent with onychophoran decay, and is therefore resolved as general for early ecdysozoans. Application of these patterns to phylogenetic data finds scalidophoran taxa to be very sensitive to taphonomically informed character coding, but not panarthropodan taxa. Priapulid decay also have unexpected relevance for interpretation of myomeres in fossil chordates. The decay data presented serve not only as a test of models of preservation but also a framework with which to interpret ecdysozoan fossil anatomies, and the subsequent evolutionary inferences drawn from them.

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Section: Methodsmentioning

confidence: 99%

“…The Priapulida, or penis worms, played a key ecosystem role as predators and infaunal bioturbators. Priapulids are known from 7 modern genera, and a diverse Cambrian fauna456. Priapulids possess a tri-layered moulting cuticle diagnosing them as ecdysozoans, and a scalid lined introvert which they share with other scalidophorans (kinorhynchs and loriciferans)7.…”

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confidence: 99%

Preservation and phylogeny of Cambrian ecdysozoans tested by experimental decay of Priapulus

Sansom

2016

Sci Rep

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“…is unknown (Schmidt-Rhaesa 2013). However, other North American species of Gordius have been reported from ground beetles (Carabidae), three families of orthopterans (Tettigonidae, Stenopelmatidae, and Acrididae) and the millipede Narceus americanus (Palisot de Beauvois 1817) (Schmidt-Rhaesa et al 2003;Poinar & Weismann 2004;Schmidt-Rhaesa 2013;Hanelt et al 2015). More importantly, our work on the biogeography of the G. cf.…”

Section: Discussionmentioning

confidence: 74%

“…This method is especially appealing for studying gordiids because virtually nothing is known about the distribution, life cycles or host use for most hairworm species (SchmidtRheasa et al 2003;Bolek et al 2015). While recent progress has been made in understanding the general life-cycle of hairworms, many questions regarding their paratenic and definitive host use in nature remain unanswered (Schmidt-Rhaesa 1997;Hanelt & Janovy 1999;Hanelt & Janovy 2003;Hanelt & Janovey 2004;Schmidt-Rhaesa et al 2003;Hanelt et al 2005;Schmidt-Rhaesa et al 2008;Bolek et al 2010;Hanelt et al 2012;Schmidt-Rhaesa 2013;Bolek et al 2013a;Bolek et al 2013b;Bolek et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Using Gordiid cysts to discover the hidden diversity, potential distribution, <br />and new species of Gordiids (Phylum Nematomorpha)

Harkins

Shannon

Papeş

et al. 2016

Zootaxa

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In this study, we sampled aquatic snails for the presence of hairworm cysts from 46 streams in Payne County, Oklahoma. Gordiid cysts were found at 70 % (32/46) of sites examined. Based on cyst morphology, we were able to identify three morphological types of gordiid cysts, including Paragordius, Gordius, and Chordodes/Neochordodes. Using our gordiid cyst presence data in conjunction with environmental variables, we developed an ecological niche model using Maxent to identify areas suitable for snail infections with gordiids. The model successfully predicted all presence localities of gordiid cysts in snails over a geographic area of 1,810 km 2 . We used this information, along with arthropod host infections and crowdsourcing, citizen scientists sampling for adult free-living worms during peak emergent times in areas predicted suitable by the model, to document Paragordius varius, Chordodes morgani, and a new species of gordiid (Gordius n. sp.). To our knowledge, this is the first ecological niche model attempted on such a narrow geographic scale (county level) that recovered known locations successfully. We provide new scanning electron micrographs and molecular data for these species. Our field data and ecological niche model clearly indicate that gordiid cysts are easy to detect in the environment and together these sampling techniques can be useful in discovering new species of gordiids, even in relatively well sampled areas for these cryptic parasites.

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“…Studies on domesticated members of these so-called hairworms have indicated that the life cycle of gordiids involves five different life stages: (1) egg strings, (2) freeliving larvae, (3) parasitic cysts, (4) parasitic juveniles, and (5) dioecious or parthenogenetic free-living adults. The larvae of the Gordiida -being benthic, microscopic, and scarcely motile-survive from three days to a few weeks after hatching, and during that time have the capacity to infect hosts that are either paratenic or definitive (Bolek, Schmidt-Rhaesa, de Villalobos, & Hanelt, 2015;Schmidt-Rhaesa, 2012). Thus, the viability of the larval stage directly after hatching will determine the success in infection and overall survival.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Infectivity of Chordodes Nobilii Larvae (Gordiida, Nematomorpha)

Achiorno

Villalobos

Ferrari

2016

RBT

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Abstract:The gordiids are freshwater representatives of the parasite phylum Nematomorpha that function as a link between aquatic and terrestrial ecosystems. In recent years, different ecotoxicologic studies have been made with the South-American gordiid species, Chordodes nobilii, that have demonstrated the capacity of this group to act as a bioindicator of contamination. Despite the Gordiida's ecologic relevance, further studies are still needed to elucidate different aspects of the biology of the class, and among those, the infective capacity, a parameter that can be evaluated by the infection index mean abundance (IIMA). A knowledge of the intrinsic variability in the infective capacity of C. nobilii would warrant priority in order to establish, the range of acceptable responses for normal or standard conditions in the laboratory, and, to compare the criteria among different assays. The objective of this study was to establish a baseline value for the infective capacity for C. nobilii larvae, under controlled laboratory conditions, by employing the IIMA as the evaluation parameter. To that end, we analyzed the infective capacity of C. nobilii larvae that had hatched from different strings of eggs laid in the laboratory by a total of 12 females. The C. nobilii adults were collected from streams within the Argentina Sauce Grande basin, between 2006 and 2009. Once in the laboratory, after mating, the females were placed in individual containers for oviposition. The egg strings obtained from each female were cut in 3 mm long segments; and when free larvae were observed, the segments (N= 90) were placed together with 30 Aedes aegypti larvae for evaluation of the gordiids' infective capacity. After 72 h, the mosquito larvae were observed by microscopy in order to quantify the C. nobilii larvae in body cavities. The IIMAs were calculated as the total number of C. nobilii larvae present divided by total number of A. aegypti larvae examined. For analysis of the IIMAs obtained, the data were grouped according to the female who made the original ovoposition. Our results enabled the corroboration of an ample range of responses in the infective capacity of this species, a characteristic that would normally be linked to the progenitors originating the hatch. Because this relationship prevents the establishment of a baseline for making comparisons among assays with gordiids, through the IIMA as a response parameter, we recommend expressing the IIMA values in each assay relative to their respective controls. These findings also provide evidence for the greater success in infections by certain members of the progeny over others. Finally, on the basis of the results obtained from this study, we stress the relevance of the use of the IIMA as a decisive aspect to be considered in different studies on the biology of Gordiida. Rev. Biol. Trop. 65 (1): 1-8. Epub 2017 March 01.Key words: parasite, Nematomorpha, infective capacity, infection index mean abundance, female.Within aquatic environments, the gordiids -freshwater representa...

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1. Gastrotricha, Cycloneuralia and Gnathifera: General History and Phylogeny

Cited by 31 publications

References 36 publications

Preservation and phylogeny of Cambrian ecdysozoans tested by experimental decay of Priapulus

Preservation and phylogeny of Cambrian ecdysozoans tested by experimental decay of Priapulus

Using Gordiid cysts to discover the hidden diversity, potential distribution, <br />and new species of Gordiids (Phylum Nematomorpha)

Analysis of the Infectivity of Chordodes Nobilii Larvae (Gordiida, Nematomorpha)

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