Cosmochlaina Temporal range: Late Silurian–Early Devonian PreꞒ Ꞓ O S D C P T J K Pg N
Cuticle of Cosmochlaina, retrieved from the Burgsvik beds by acid maceration. Cells about 12 μm in diameter.
Scientific classification
Kingdom:	Plantae (?)
Phylum:	†"Nematophyta"
Class:	†Nematophytina
Order:	†Nematophytales
Family:	†Nematothalaceae Strother 1993
Genus:	†Cosmochlaina Edwards 1986
Species
C. verruculosus (May be a typo, in Taylor 1988) C. verrucosa (Type) C. maculata C. physema C. Versiformis (All defined by Edwards 1986)

Cosmochlaina (from Greek: kosmos=ornament; xlaina=wrapper/cloak) is a form genus of nematophyte – an early (Silurian – Devonian) plant known only from fossil cuticles,^[1] often found in association with tubular structures.^[2] The form genus was put forwards by Dianne Edwards, and is diagnosed by inwards-pointing flanges and randomly oriented pseudo-cellular units.^[3] Projections on the outer surface are always present, and sometimes also appear on the inner surface; however, the surface of the cuticle itself is always smooth.^[3] The holes in the cuticle are often covered by round flaps, loosely attached along a side.^[3]

Where Nematothallus was sometimes used to relate only to tube-like structures, Cosmochlaina was used in reference to the cuticle fragments. Material discovered later revealed its internal anatomy, which comprises a lichen-like mat of 'hyphae'.^[4]

It has been suggested that the pores of Cosmochlaina represent broken-off rhizoids, on the basis that rotting and acid treatment of extant liverworts produces a similar perforated texture.^[5] However, the status of this form genus in any one kingdom is not secure; members could, for example, represent arthropod cuticle.^[6] Alternatively, different species may in fact represent different parts of the same organism.^[3] Based on the more recent material, a lichen affinity seems most plausible.^[7]

• Nematothallus, a closely related sister taxon
• Evolutionary history of plants