Margarinotus ephemeralis

Very similar to Margarinotus remotus but distinguished by pronotal punctuation. The specific pattern of elytral striae—particularly the abbreviated or nearly absent fifth stria—provides additional diagnostic characters. The single lateral stria on the pronotum is a key feature for genus-level identification within Histeridae.

Oblong oval body measuring 3.8–5.2 mm in length and 2.7–3.2 mm in width. Elytra with five striae: first three complete, fourth complete or slightly abbreviated, fifth restricted to apical half or less and sometimes nearly absent. Prothorax with convergent, arcuate sides. Pronotum with a single lateral stria.

Associated with burrow systems of California ground squirrel (Otospermophilus beecheyi). Specimens have been collected from burrow entrances and from temporary pools, suggesting occupation of subterranean spaces subject to periodic flooding.

Known only from southern California, USA. No records from other regions.

• Otospermophilus beecheyi - inquilinePotential obligate inquiline; specimens collected from burrow entrances and flood pools

Specimens have been found at burrow entrances of California ground squirrels and in temporary pools, suggesting displacement from subterranean habitats during flooding events. This pattern indicates a subterranean lifestyle closely tied to mammal burrow systems.

Histeridae are generally predatory on other insects and their larvae; specific ecological function of this species is unknown but likely involves predation on other invertebrates within squirrel burrow microhabitats.

• Margarinotus remotusVery similar morphology; distinguished by pronotal punctuation pattern

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon