Community Evidence Grading Standard

Someone posts three photos of a slime mold and asks for identification. The first response says “definitely Physarum polycephalum.” The second says “could be Fuligo.” The third says “need more info.” All three people looked at the same images. Their conclusions differ.

The problem is that online identification lacks a shared standard for evidence quality. One person sees a yellow blob and names a species. Another waits for diagnostic structures that never arrive. This guide provides a grading system that makes evidence quality explicit.

What evidence grading does

Evidence grading answers one question: how much identification confidence does the current evidence support? It does not tell you the correct identification. It tells you whether your evidence is strong enough to support any identification at all.

This distinction matters because confidence and correctness are different things. A confident wrong answer is still wrong. A tentative correct answer is still correct. Grading evidence separates the quality of the documentation from the accuracy of the conclusion.

When a community adopts a grading standard, several things improve. New members learn what good evidence looks like. Experienced identifiers can point to the standard instead of repeating the same explanations. Moderators have a consistent framework for evaluating claims.

Key terms

Evidence package: The complete set of photos, notes, metadata, and context attached to an identification request. A complete package includes habitat, scale, stage, and structural details.

Diagnostic trait: A feature that can eliminate competing species when observed clearly. Examples include spore ornamentation, capillitium attachment pattern, and peridium opening behavior.

Supportive trait: A feature that helps narrow possibilities but cannot confirm identity alone. Color, general shape, and substrate are usually supportive rather than diagnostic.

Stage-aware evidence: Evidence that documents the maturity stage of the specimen. Immature, mature, and degrading specimens show different traits.

The grading scale

This standard uses a six-tier scale from A to F. Each grade describes what identification confidence the evidence justifies.

Grade A: Complete evidence

The evidence package includes all necessary components. Habitat context is visible. Scale is present. The maturity stage is documented. At least one diagnostic trait is clearly captured. Observation and interpretation are separated in the notes.

What Grade A supports: Genus identification with high confidence. Species identification is possible in groups where visible traits are diagnostic. Microscopy may still be required for difficult groups.

Example: A post showing pink cushion-like fruiting bodies on dead oak, with close-up of smooth-warty surface, scale reference, and notes distinguishing observation from interpretation. This supports a Lycogala genus identification and a provisional L. epidendrum species identification pending microscopy.

Grade B: Strong evidence with one gap

The evidence package is nearly complete but missing one important element. Perhaps the scale is absent, or the opening stage was not captured, or one diagnostic trait is unclear.

What Grade B supports: Provisional identification with explicit limitation. The identifier states confidence but notes what evidence would strengthen or change the conclusion.

Example: Good photos of stalked brown sporocarps with visible capillitium, but no scale reference. The identifier can state “consistent with Stemonitis based on capillitium pattern, but size cannot be confirmed without scale.”

Grade C: Mixed evidence

The evidence package contains useful information but lacks diagnostic traits. Photos show the specimen clearly, but the features that would separate species are not visible or not captured.

What Grade C supports: Genus-level or group-level identification only. Species-level claims are not supported.

Example: A top-view photo of a yellow plasmodium on mulch. The identifier can say “plasmodial slime mold, possibly Fuligo or Physarum, but species identification requires fruiting structures.”

Grade D: Low evidence

The evidence package has major gaps. Photos may be blurry, lack context, or show only one angle. Critical structures are not documented.

What Grade D supports: No taxonomic claim. The appropriate response is to request additional evidence before attempting identification.

Example: A single blurry photo of something brown on bark. The appropriate response is “cannot identify from this image, please provide clearer photos with scale and multiple angles.”

Grade E: Poor evidence

The evidence is essentially just a visual impression. No structural details are visible. The photos might as well be abstract art for identification purposes.

What Grade E supports: Descriptive note only. No taxonomic claim of any rank.

Example: A photo of “something yellow in my garden” with no scale, no context, and no visible structure. The response should focus on teaching what evidence is needed.

Grade F: Conflicting or unusable evidence

The evidence contradicts itself or is too poor to evaluate. Multiple photos might show different specimens mixed together, or the images might be too dark or overexposed to see anything.

What Grade F supports: Reset the case. Ask the poster to start over with a fresh collection.

The scoring workflow

For moderators and experienced reviewers, here is a systematic way to assign grades.

Step 1: Score technical completeness

Evaluate each component and assign 0 to 2 points:

Stage coverage (0-2 points)

• 2: Maturity stage clearly documented, possibly with time series
• 1: Stage can be inferred but not confirmed
• 0: No stage information

Scale reference (0-2 points)

• 2: Clear scale in frame, size can be measured
• 1: Scale present but unclear or partial
• 0: No scale reference

Diagnostic structure visibility (0-2 points)

• 2: At least one diagnostic trait clearly visible
• 1: Structures visible but not diagnostic quality
• 0: No useful structural detail

Observation quality (0-2 points)

• 2: Sharp, well-lit, multiple angles
• 1: Acceptable but with some limitations
• 0: Poor quality, blurry, or badly lit

Metadata clarity (0-2 points)

• 2: Location, date, substrate all provided
• 1: Partial metadata
• 0: No context information

Total score interpretation:

• 9-10 points: Grade A candidate
• 7-8 points: Grade B candidate
• 5-6 points: Grade C candidate
• 3-4 points: Grade D candidate
• 0-2 points: Grade E or F

Step 2: Check claim discipline

Even a high-scoring package can be downgraded if the claims exceed the evidence. Look for these problems:

• Species certainty from one top-view photo
• Confidence language not matched to evidence quality
• No distinction between observation and interpretation
• Color treated as diagnostic when it is not

If any of these appear, lower the grade by one or more tiers depending on severity.

Step 3: Issue a bounded outcome

Use standardized language for the result:

• “Accepted as genus identification based on Grade A evidence.”
• “Accepted as provisional identification pending one diagnostic trait. Current evidence Grade B.”
• “Evidence Grade C supports only group-level identification. Species claim not supported.”
• “Evidence Grade D insufficient for identification. Requesting additional photos.”
• “Evidence Grade E. Please review evidence requirements and resubmit.”

Evidence grades are not verdicts

A high grade does not guarantee that the identification is correct. It means the claim is supported by available evidence. New evidence can overturn any identification.

Conversely, a low grade does not mean the identification is wrong. The poster might have correctly guessed the species based on limited evidence. The grade only reflects whether the guess is supported.

The goal is not to be right. The goal is to be honest about what the evidence supports.

What to do next

If you are a community member posting identification requests:

1. Review the Grade A checklist before posting.
2. Include scale, context, and multiple angles.
3. Separate what you see from what you think it means.
4. Accept that low-grade evidence produces limited answers.

If you are a moderator or reviewer:

1. Apply the scoring workflow consistently.
2. Use standardized language for outcomes.
3. Teach by explaining what evidence is missing, not just that it is missing.
4. Model good evidence practice in your own posts.

Related guides

• Voucher Metadata Requirements for Expert ID
• Conflict Resolution Protocol for Advanced ID
• Nickname to Taxonomy Translation Lexicon
• Slime Mold Look-alikes
• Glossary