Smeadia clevelandensis Gen. et sp. nov. from the Upper Devonian Cleveland Shale of Ohio, U.S.A.
Chitaley, Shya;Li, Cheng-Sen
published: Dec 15, 2004
A new herbaceous lycopsid is described from the Upper Devonian of Cleveland, Ohio, U.S.A. It is represented by three charcoalified pieces, collected during 1965-68 from the Cleveland Shale exposed at the intersection of the West 130th Street and Route I-71 of the Greater Cleveland area. Three of the four pieces collected fit well with each other end to end but do not interlock . The combined length of the specimen is 71 mm, and it is 4 mm in diameter. Morphologically and anatomically all the three pieces are very similar indicating that they belong to the same specimen. They have helically arranged, scaly lycopsid leaves, and leaf scars are without leaf cushions. The cross section of the axis shows many advanced characters including a small central parenchymatous pith surrounded by exarch xylem and parenchymatous cortex; protoxylem tracheids showing annular thickenings with weak striations, while the metaxylem tracheids have multi-perforated bordered pits and Williamson’s striations. The phloem is not well preserved. The cortex is differentiated into an inner zone showing leaf traces, the middle with large rounded cells with fibres and the outer composed of thick-walled large oblong cells with many fibres. The elongated epidermal cells have stomata. One of the pieces has an oval to globular terminal strobilus with poorly preserved trilete spores in tetrads. Comparisons with other herbaceous Devonian lycopsids show that this slender specimen with a compact strobilus is sufficiently different in many characters to warrant its inclusion into a new genus and species, Smeadia clevelandensis. The presence of this specimen in the Upper Devonian Cleveland Shale is of great significance. This is the first herbaceous lycopsid reported from this shale suggesting the proximity of the coastal margin of the Ohioan Sea where it grew before drifting a short distance and sinking to the bottom sediments at Cleveland. The additional fourth piece of the axis collected does not fit in with any of the above three pieces, though in size and in morphological and anatomical characters it is the same.