Pileiform

Definition

Shaped like a cap or pileus; having a broad, convex, umbrella-like or shield-like form resembling the cap of a mushroom or the pileus of a mollusk shell. In invertebrate morphology, describes structures that are rounded, often with a central depression or umbo, and typically wider than tall.

Etymology

From Latin pileus (cap, especially a felt cap or mushroom cap) + -formis (shaped like)

Example

The mite Nothrus pileiformis bears a dorsal shield with a distinctly pileiform outline, the broad convex carapace resembling a small cap over the idiosoma; similarly, the fungal apothecium of Galeoscypha pileiformis opens as a pileiform disc to expose the hymenium.

Synonyms

• pileate
• pileous
• calyptiform

Related Terms

• pileus
• calyx
• umbonate
• patelliform
• clypeiform
• scutiform

Usage Notes

Distinguished from patelliform (saucer- or dish-shaped, flatter) and clypeiform (shield-shaped, often with a different aspect ratio); pileiform emphasizes the convex, cap-like profile with a tendency toward central thickening or an umbo. In arachnology, often describes the outline of dorsal shields or the shape of sclerotized plates in Oribatida. Pronunciation varies between PY-lee-ih-form (classical Latin) and PILL-ee-ih-form (anglicized).