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System observation or method study Direct Neocaridina evidence

Distribution of Holtodrilus truncatus, a Branchiobdellidan Ectosymbiotic on Atyid Shrimps in the Kii Peninsula, Western Japan, with Reference to Salinity Tolerance and Host Preference

Tanaka, Wada and Hamasaki, 2016. Zoological Science 33(2): 154-161.

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This record is a claim boundary, not a quality badge. Evidence class and species relationship describe what was studied. They do not make the result universal, complete or automatically applicable to a home aquarium.

Source taxon as published
Holtodrilus truncatus; field hosts included Paratya compressa, Caridina leucosticta, Caridina multidentata, Caridina typus and Neocaridina denticulata
Environment
Field collections at one to eight sites in each of 26 rivers on the Kii Peninsula, Japan, plus 22 to 27 C freshwater laboratory salinity and two-host choice tests
Life stages
field-collected atyid shrimp, isolated large Holtodrilus truncatus approximately 5 mm long, similar-sized non-ovigerous male or female shrimp in host-choice tests
Reviewed
2026-08-12

What was studied

Study shape: The field survey standardized dip-net sampling at ten waterside areas per site and repeated one river seasonally. The salinity study exposed 24, 20, 30, 25 and 12 host-removed worms to nominal 0, 0.5, 1, 1.5 and 3 percent salinity without food, with observation intervals that shortened as salinity rose. Host-choice tests placed one worm with a size-matched pair of Paratya compressa, Caridina leucosticta or Caridina multidentata for 40, 36 and 39 pairwise replicates.

Experimental unit: Field host shrimp for occurrence endpoints; an incompletely reported small plastic tank holding two or five isolated worms for salinity exposure; and one worm with one two-shrimp species pair for each host-choice replicate

Endpoints: river and host occurrence, prevalence and intensity on Paratya compressa, host body location, Paratya compressa egg number association, isolated-worm attachment-defined survival, selected host in pairwise choice.

Claim boundary

What it can support: Holtodrilus truncatus occurred in 10 of 26 surveyed rivers and on five atyid host species. The only two examined N. denticulata were both recorded with the worm, which establishes occurrence but not prevalence. Isolated-worm survival declined with increasing nominal salinity, including significantly lower survival at 0.5 than 0 percent. In pairwise tests that excluded Neocaridina, worms selected P. compressa over both Caridina species and C. leucosticta over C. multidentata. Cohabitation was not associated with egg number in the measured P. compressa model.

What it cannot support: The direct Neocaridina result is two field animals, not a representative sample. No Neocaridina entered the salinity, host-choice or egg-number analyses. Worms were removed after the host carapace was detached, so salinity was tested on isolated organisms rather than attached worms or living host shrimp. The work measured no treatment efficacy on a host, shrimp survival, sublethal host effect, recurrence or safety margin. Worms shared exposure containers in groups of two or five, the number of independent tanks was not reported, checking frequency differed by concentration, no food was provided, and floating or failure to attach was classified as death. Nominal salinity tolerance cannot validate a salt dip, 30-second exposure, host-safe dose or Neocaridina host preference.

Publication status audit

Canonical DOI outside query result

The record has a canonical DOI but did not appear in the broad Neocaridina query. It requires DOI-specific or alternative-registry status review before any no-update statement.

Metadata snapshot reviewed 2026-08-12. Inspect the method, unmatched queue and limitations.

Correction impact

If this source boundary changes, these are the known downstream consumers. The list distinguishes scientific re-review from generated parity and historical follow-up.

Editorial review required (9)

This curated wording or synthesis must be reconsidered when the source boundary changes. A passing generator test cannot decide the new scientific meaning.

  • anatomy decision card Tank-side decision card
    The card translates this guide into an observation, first action, next record and stopping boundary, so all four require editorial review when the source changes.
  • health decision card Tank-side decision card
    The card translates this guide into an observation, first action, next record and stopping boundary, so all four require editorial review when the source changes.
  • quarantine decision card Tank-side decision card
    The card translates this guide into an observation, first action, next record and stopping boundary, so all four require editorial review when the source changes.
  • anatomy practical guide Practical guide
    The guide uses this evidence record and its practical wording must remain inside the revised source boundary.
  • health practical guide Practical guide
    The guide uses this evidence record and its practical wording must remain inside the revised source boundary.
  • quarantine practical guide Practical guide
    The guide uses this evidence record and its practical wording must remain inside the revised source boundary.
  • treatment-efficacy knowledge gap Canonical knowledge gap
    The current knowledge-gap boundary depends on a dated search that used this exact source and must be reconsidered if the source meaning changes.
  • treatment-efficacy answerability brief Answerability brief
    The decision, endpoint, minimum design or closure rule may change when evidence used in the linked gap search is corrected.
  • treatment-efficacy research allocation Current research allocation
    The current allocation, activation trigger, next permitted unit or stop decision may change when evidence used in the linked gap search is corrected.

Generated from governing registry (16)

This surface derives from a governing registry and should update with it, but release tests must still prove parity and routing.

Historical record needs follow-up decision (1)

Do not silently rewrite history. Decide whether the prior change record remains accurate and publish a new correction or scope note when needed.

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How this record is classified

System observation or method study: An aquarium, analytical or biological system was observed without an assigned Neocaridina animal treatment. The species relationship still identifies whether the evidence is biological or system-adjacent.

Direct Neocaridina evidence: The source measured animals named within Neocaridina. Direct still does not mean universal or sufficient.

Topics: Health, Anatomy, Species and taxonomy, Water parameters, Wild populations

Critically appraise this source without a score

These questions fit this record's system observation or method study role. They are prompts, not automatic judgments. Open the original source to answer them.

  1. Identity and provenance: How were the organism, population, stock and life stage identified and sourced? A published name or seller label can hide a taxonomic, population or life-stage transfer.
  2. Independent unit: What unit was independently assigned or sampled, and how many units support each comparison? Animal counts do not create independent replication when animals share a vessel, site, family or treatment history.
  3. Comparison and context: What was the actual comparator, allocation process, environment, duration and material condition? A result has meaning only against the comparison and conditions that produced it.
  4. Endpoint and measurement: Which endpoint was measured, with what method, unit, timing, resolution and decision rule? One endpoint cannot silently become survival, welfare, diagnosis, reproduction or long-term population performance.
  5. Denominators and missingness: Are starting counts, exclusions, losses, missing observations and analysis denominators reconciled? Unreported or changing denominators can alter the apparent direction, precision and applicability of a result.
  6. Transfer boundary: What is the nearest tempting aquarium claim that this source design cannot establish? Direct evidence can still be narrow, and adjacent evidence can be useful only while the inference remains visible.
  7. System relationship: Was the measured unit an aquarium system, analytical method, another taxon or another biological level? A system or method result is not automatically a Neocaridina animal response.
  8. Inference mechanism: What explicit mechanism or shared property makes the adjacent evidence relevant? Similarity must be stated and tested rather than assumed from a broad label.
  9. Target validation: Has the method or inference been validated in Neocaridina, the intended water, life stage and decision range? Analytical validity in one matrix or biological validity in another species may not transfer.
  10. Permitted use: Is the source being used only for its method or system role rather than promoted to animal evidence? Useful adjacent evidence becomes misleading when its role is silently upgraded.

Read the complete appraisal framework.

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