Re-investigation of Bowmanites laxus Halle, 1927, a sphenopsid fructification from the Permian of China

Abstract

Halle (1927) described and illustrated sphenopsid plant remains from Permian strata (Shihottse Formation) in Shanxi Province, China in the early 1920s. He designated the particular stratigraphic sources as Plant Bearing Beds 14 and 31 and described Bowmanites laxus, n. sp. from the former and Bowmanites sp. from the latter. The illustrated specimens, as well as additional ones from both beds were borrowed from the Palaeobotanical Collections of the Swedish Museum of Natural History, Stockholm, Sweden and re-investigated in order to prepare, re-illustrate, describe, and compare the species. The preparations revealed that the leaves in both species have the same morphology in the strobili as well as in the sterile axes and are arranged in open, not laterally fused whorls. Each leaf is arcuate and upwardly turned, the lamina is narrow at the point of attachment，and gradually expanded to become bilaterally laciniate and medially elongated into a sharply pointed apex. The sporangiophore in both species is axillary to the subtending sporophyll, remains free, following the upward curve of the sporophyll, and terminally, bears two peltately suspended sporangia that are aligned parallel to the lamina of the sporophyll. A single lectotype is chosen from/among the lectotype suite previously defined by Hoskins and Cross (1943). A systematic classification of the species is proposed. The summary of revisions of other sphenopsid species as suggested by Hoskins and Cross (1943) is presented in relationship to their proposal to divide the species of Bowmanites into three Sections in one of which B. laxus is included.