identifier: traitmech:000677
label: fungal constricting-ring trap formation
definition: A morphological phenotype in which a fungus forms three-celled hyphal
  ring traps whose mature ring cells inflate inward to mechanically capture nematodes.
definition_source: DOI:10.1038/s41467-023-43235-w
trait_category: MORPHOLOGY
term_kind: CLASS
mapping_status: PROPOSED
parent_traits:
- traitmech:000718
evidence:
- reference: DOI:10.1038/s41467-023-43235-w
  snippet: The R3 cell fuses with the S2 and R1 cells to complete CR formation
  notes: Chen et al. (2023), Results, Morphogenesis and development of CR; primary
    XML at https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10651832/fullTextXML
    and actual Figure 1 inspected. CR means constricting ring; R1-R3 are ring cells
    and S1-S2 stalk cells. Wild-type Drechslerella dactyloides strain 29 (CGMCC3.20198)
    forms complete rings before becoming inflation-competent. Methods use water agar
    at 25 degrees C with Caenorhabditis elegans for induction, and nematodes or 55-degree-C
    water for inflation assays; a separate horse-serum protocol is also described.
    These are distinct assay conditions, not universal requirements. Figure 1 separates
    immature-ring escape from mature-ring capture. Neither formation alone nor a circular
    outline proves immediate capture competence.
- reference: DOI:10.3897/BDJ.10.e96642
  snippet: Both of them produce constricting rings to capture nematodes.
  notes: Zhang et al. (2022; published 16 December), scientific abstract, New information;
    primary XML at https://www.ebi.ac.uk/europepmc/webservices/rest/PMC9836436/fullTextXML.
    The two taxa are Drechslerella daliensis and D. xiaguanensis. Methods, taxon descriptions
    and actual Figure 1e were inspected. Soil isolates were purified by single-spore
    transfers; trapping structures were induced on corn meal agar observation plates
    at 26 degrees C using Panagrellus redivivus. Descriptions distinguish three-celled
    constricting rings from adhesive trapping devices. Figure 1e shows an uninflated
    ring, not time-resolved inflation. The taxon-name validity caveat is retained
    in the example.
- reference: DOI:10.1016/j.devcel.2014.04.021
  snippet: Cytokinesis involves constriction of a contractile actomyosin ring.
  notes: Stachowiak et al. (2014), scientific abstract retrieved from Europe PMC for
    PMID:24914559, and primary article https://pmc.ncbi.nlm.nih.gov/articles/PMC4137230/.
    Results explicitly use constricting-ring terminology for intracellular actomyosin
    rings in fission-yeast protoplasts. This is terminology-boundary evidence, not
    another positive nematode-trap observation. The trap qualifier excludes this unrelated
    cellular structure; no cytokinesis mechanism, protein grounding or canonical example
    is transferred.
canonical_examples:
- taxon_id: NCBITaxon:2743661
  taxon_label: Drechslerella daliensis (nom. inval.)
  reference: DOI:10.3897/BDJ.10.e96642
  note: Source-named D. daliensis, holotype culture CGMCC3.20131, isolated from burned
    forest soil at Cangshan Mountain, Dali, Yunnan, China, collected 25 July 2017.
    The primary taxon treatment and Figure 1e directly document three-celled constricting
    rings. Morphology and ITS, TEF1-alpha and RPB2 analyses support the study's identification.
    Live NCBI https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=taxonomy&id=2743661
    resolves rank species but retains the nomenclatural qualifier nom. inval.; this
    is not a claim that the fungal name is validly published. The example is restricted
    to the observed culture and induction conditions, not every isolate or successful
    field biocontrol.
discussions:
- discussion_id: constricting-ring-scope-and-parent
  prompt: Resolve a closer trap-morphology parent without conflating cell shape.
  kind: CURATION_TODO
  status: RESOLVED
  rationale: Parent phenotype METPO:1000059 is broader than this multicellular differentiation
    phenotype. Ring shaped METPO:1000680 denotes individual cell geometry, not a three-cell
    trapping apparatus. Mycelial growth and hyphal anastomosis alone do not define
    this trap. Exclude adhesive non-constricting rings, adhesive nets and generic
    nematophagy; neither a taxonomic genus nor prey capture by any mechanism is an
    exact synonym. Formation includes morphologically complete immature rings, not
    only already inflated traps. Do not infer that every formed ring immediately inflates.
    No xrefs, synonyms, SSSOM mappings or organism-level disjointness are asserted;
    closer hierarchy remains open. Stachowiak et al. (2014), DOI:10.1016/j.devcel.2014.04.021,
    also use constricting-ring terminology for fission-yeast cytokinesis. The trap-qualified
    label explicitly excludes those intracellular actomyosin rings; they are not synonyms
    or phenotype evidence here.
  posed_by: codex
  posed_date: '2026-10-08'
  resolved_date: '2026-10-13'
  resolution_note: Added fungal nematode-trap formation traitmech:000718 as the direct
    broader phenotype. The existing child definition entails specialized hyphal trap
    differentiation. This resolves only the parent gap; the historical scope contrasts,
    unasserted mappings, examples and separate mechanism questions remain applicable.
    Formation does not guarantee immediate capture. The column cell-count question
    is separately OPEN. Preserve the historical phenotype axiom and add METPO:1063000
    SubClassOf METPO:1067100 on upstream adoption.
- discussion_id: constricting-ring-mechanism-and-taxonomy
  prompt: Separate trap formation, inflation mechanism and nomenclatural validity.
  kind: KNOWLEDGE_GAP
  status: OPEN
  rationale: Chen et al. investigate membrane reservoirs and SNARE-dependent inflation,
    but a protein-resolved causal graph requires review of the remaining perturbation/complementation
    figures, supplements and taxon-paired accessions. No universal SNARE requirement
    is inferred from morphology; mechanism is deferred, not claimed absent. Native
    provenance of laboratory strain 29 has not been established here, so it remains
    qualified evidence rather than a natural canonical example. NCBI's nom. inval.
    qualifier for D. daliensis concerns nomenclature, not absence of the observed
    trap; retain it pending nomenclatural review.
  posed_by: codex
  posed_date: '2026-10-08'
curation_history:
- timestamp: '2026-10-08T08:53:27Z'
  curator: codex
  action: MINTED_TRAITMECH_ID
  changes: Added fungal constricting-ring formation with two primary DOI sources,
    source-checked snippets and a nomenclature-qualified natural-isolate example.
    Ignored-and-hidden main/worktree/open-PR checks support 000677 and v553 block
    1063000-1063099. Separated formation from maturation, inflation and capture; existing
    records unchanged. Timestamp is observed UTC.
  llm_assisted: true
- timestamp: '2026-10-08T09:13:13Z'
  curator: codex
  action: EVIDENCE_AND_SCOPE_CORRECTION
  changes: 'Addressed #1823: qualified the label with trap to distinguish intracellular
    cytokinetic rings in fungi. Added a directly checked primary boundary-source snippet
    and explicit exclusion; it is not a third positive trap study. Preserved the initial
    event, definition, identifier, natural example and reservation.'
  llm_assisted: true
- timestamp: '2026-10-13T13:31:56Z'
  curator: codex
  action: REFINE_FUNGAL_TRAP_PARENT
  changes: Refined traitmech:000677 below fungal nematode-trap formation traitmech:000718
    and resolved its temporary parent discussion by definition-based inference. Preserved
    child identity, definition, evidence, examples, mechanism gaps and earlier history.
  llm_assisted: true