A new Jurassic Phlebopteris (Plantae, Filicales) from the Wallowa Terrane in the Snake River Canyon, Oregon and Idaho

Abstract

A new species of the fern Phlebopteris, P. tracyi n. sp., is described from the Jurassic Coon Hollow Formation in the Wallowa terrane in the Snake River Canyon, Oregon and Idaho. The leaf is as large or larger than all specimens of previously described species of Phlebopteris. The pinnae of the new species are divided into many widely spaced, narrow, elongate pinnules that have obtusely pointed apices. Each pinnule contains a strong midrib from which lateral veins arise at a high angle and give off anastomosing branch veins. The fertile pinnae bear circular superficial sori arranged in a single row on each side of midrib. The new Phlebopteris occurs beneath a horizon containing marine fossils of Middle Jurassic age. The presence of P. tracyi in the Coon Hollow Formation indicates that it was deposited under a humid, warm to hot climate.