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]
^ abcdEdwards, D. (1986). "Dispersed cuticles of putative non-vascular plants from the Lower Devonian of Britain". Botanical Journal of the Linnean Society. 93 (3): 259–275. doi:10.1111/j.1095-8339.1982.tb01025.x.
