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coenobium formation

traitmech:000655 · CLASS · PROPOSED

A morphological phenotype in which an alga forms clonal multicellular colonies whose cell complement is established during colony formation, with subsequent colony growth by cell enlargement rather than addition of cells.

Trait evidence (3)

  • DOI:10.1098/rspb.2023.1882
    characteristically form clonal colonies of fixed cell number known as coenobia.

    Harvey (2023), PMID:37876191, PMC10598416, Comparisons with extant taxa. Direct full-text terminology passage covers Volvocales, Scenedesmaceae and Hydrodictyaceae. Growth after colony formation is by cell expansion; a later reproductive cycle makes daughter colonies. This comparison supports terminology, not a new experiment on living algae; the paper's fossil developmental reconstruction remains an inference.

  • DOI:10.1242/jcs.212233
    progeny were unicellular in three species and multicellular (joined in a sheet-like coenobium) in two.

    Cardon et al. (2018), PMID:29487180, scientific abstract. Primary Results, Methods and actual Figure 1 were inspected. The coenobial species are Enallax costatus and Tetradesmus obliquus; multiple fission occurs in all five tested species and alone does not establish coenobial progeny. Figure 1 supports joined-cell morphology. Release is author-reported in the Results, not visible in Figure 3; supplementary Figure S1 and movies were not directly inspected.

  • DOI:10.1038/s41598-018-28627-z
    monocultures of D. opoliensis in the control groups (without IAA treatment) were dominated by two-celled and four-celled coenobia

    Chung et al. (2018), PMID:29980731, PMC6035231, Results. Direct full text reports this morphology after one week; Methods describes native isolates cultured in CA medium. Higher indole-3-acetic acid concentrations favor unicells in the tested monocultures, so IAA is not a universal coenobium inducer. No percentage, causal protein claim or direct figure inspection is asserted here.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.1098/rspb.2023.1882

Parent traits (1)

kg-microbe context

No kg-microbe node embedding matched this record in the 2026-04-25 deepwalk.

Canonical examples (1)

Organisms cited as exemplars of this trait. Taxon ids are NCBITaxon and link out to the NCBI record.

  • Enallax costatus NCBITaxon:113528 DOI:10.1242/jcs.212233 CCAP 276/31 (paper: CCAP 276-31), grown at 25 C on a 12:12 light/dark cycle in a 1:1 mixture of Bold's basal medium with micronutrients and Woods Hole medium. Figure 1 and Results document coenobial morphology, not an invariant state for every life stage. Collection provenance at https://www.ccap.ac.uk/catalogue/strain-276-31 identifies Hegewald's 1980 Finnish lake isolate and lists GMO: No. The paper describes unialgal cultures, not axenic cultures.

Discussions and Knowledge Gaps (2)

Open questions attached to this trait. Seeded by just knowledge-gap-scan and curated; see the corpus-wide index.

Review a multicellular morphology parent and exact mappings.

CURATION TODO OPEN coenobium-formation-scope-and-hierarchy · raised by codex · 2026-10-07

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

Retain phenotype METPO:1000059. Cell shape METPO:1000666 is individual-cell morphology; colony morphology METPO:1007062 concerns macroscopic colony characteristics. Obsolete cell arrangement METPO:1000046 and aggregate METPO:1000011 are not active parents. Palmelloid formation traitmech:000654 covers mother-wall retention or extracellular adhesion, not this developmental cell-complement criterion. Rosette cell arrangement traitmech:000652 requires inward cell poles, and biofilm formation traitmech:000053 requires surface attachment; neither is required here. A coenocyte is a multinucleate cell, not a multicellular coenobium. No exact synonym, xref or organism-level disjointness is asserted.

Resolve organism-specific colony development before graphing.

KNOWLEDGE GAP OPEN coenobium-formation-development-and-mechanism · raised by codex · 2026-10-07

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

Fixed cell complement describes an individual colony, not one invariant count across taxa or conditions. Reproduction can form new daughter colonies. Harvey's extant comparisons include motile forms and Volvox germ-soma differentiation; Chung's introductory little-or-no-specialization formulation is not imposed universally. Neither a sheet shape, common wall, power-of-two count, lack of flagella nor grazer induction defines the class. Defer a causal graph pending perturbation and accession-level evidence: Cardon's observed Golgi localization and cell rotation do not demonstrate causal necessity for coenobium formation. Gene possession alone does not establish this phenotype.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    Added coenobium formation with three DOI-backed snippets, a qualified Enallax costatus example and developmental scope boundaries. Ignored-and-hidden searches and structured METPO review found no exact record. Reserved METPO:1060800 in v531; existing records unchanged.

Recorded curation sessions

  • · codex
    • CREATE — Add evidence-backed coenobium formation

      Minted traitmech:000655 with three DOI-backed snippets, a qualified Enallax costatus CCAP 276/31 example, and hierarchy/developmental-mechanism discussions. Reserved METPO:1060800 in proposal v531. No causal graph or exact external mapping is asserted. Existing trait records remain unchanged.

    Read this curation session