Triskelia scotlandica, an enigmatic Rhynie chert microfossil revisited

Krings, Michael (2020): Triskelia scotlandica, an enigmatic Rhynie chert microfossil revisited. In: Palz, Bd. 95, Nr. 1: S. 1-15

Abstract

The enigmatic microfossil Triskelia scotlandica from the Lower Devonian Rhynie chert is an acritarch-like, usually spheroidal to ovoid vesicle with a surface ornamentation comprised of isolated triradiate and meandering, high membranous ridges. The form has been formally described based on dispersed specimens preserved inside the remains of a land plant axis, and interpreted as the resting stage of a microscopic alga. Unusual microbial coatings on land plant axes from the Rhynie chert have recently yielded > 300 additional specimens of T. scotlandica, many of which occur in situ in prominent swellings of fungal hyphae. This discovery is a strong evidence that T. scotlandica is not algal, but rather fungal or fungus-like in nature. The swellings might be oogonia of a representative of the Oomycota (e.g., Saprolegniales), and T. scotlandica accordingly an ornamented oospore. However, specimens with a discharge tube suggest that T. scotlandica is more likely a zoosporangium or resting spore stage of an endoparasite, perhaps with affinities to the holocarpic Oomycota (e.g., Olpidiopsis), Cryptomycota (e.g., Rozella), or zoosporic fungi (e.g., Olpidium), in which case the hyphal swellings would be either dilatations resulting from the expansion of the parasite inside, or a host response (hypertrophy). The affinity of T. scotlandica remains unresolved, due in part to the uncertain diagnostic value of the surface ornamentation, and because no other stages of the life history of this organism are known. Nevertheless, the new specimens expand our knowledge of the microbial interactions that existed in early terrestrial ecosystems.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Geowissenschaften > Department für Geo- und Umweltwissenschaften
• Themengebiete: 500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie
• ISSN: 0031-0220
• Sprache: Englisch