Ricinulei

Ricinulei are an order of arachnids called hooded tickspiders. Their defining feature is a movable hood that covers the mouthparts.

Arachnid: An arthropod in the class Arachnida, typically with four pairs of walking legs and no antennae. Ricinulei are one order within this broader group of arthropods.
Cucullus: The movable hood covering the mouthparts in ricinuleans. This specialized structure gives the order its defining anatomical character.
Paleozoic: The geological era spanning about 539 to 252 million years ago. Ricinulean fossils extend back to the Carboniferous, within this era.
Cryptocellus: A genus of living ricinuleans found in the Americas. It represents a major living lineage of the order in the New World.
Arthropod: An invertebrate animal with a segmented body, jointed appendages, and an external skeleton. Ricinulei share the jointed limbs and exoskeleton characteristic of arthropods.
Pedipalp: A paired appendage near the mouth in arachnids, used for sensing, feeding, or reproduction. Male ricinuleans use modified pedipalps to transfer sperm.
Carboniferous: A geological period from about 359 to 299 million years ago. The oldest known ricinuleans come from Carboniferous deposits.
Ricinoides: A genus of living ricinuleans native to tropical Africa. Its species show the order’s distribution beyond the Americas.
Prosoma: The anterior body region of an arachnid, bearing the mouthparts and walking legs. The movable hood is attached to the prosoma and covers its mouthparts.
Genital operculum: A plate-like covering over the genital opening in some arachnids. In ricinuleans, this structure is associated with their distinctive reproductive anatomy.

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