MUTOVIASPERMUM KRASSILOVII GEN. ET SP. NOV.: A PECULIAR COMPOUND OVULIFEROUS CONIFER CONE FROM THE LOPINGIAN (LATE PERMIAN) OF EUROPEAN RUSSIA (VOLOGDA REGION)

摘要

Premise of research. Late Permian Voltziales are interpreted to have given rise to most extant conifer families, although their origin and evolutionary relationships are still poorly understood. The Poldarsa Formation (Kichuga Member) of Mutovino (=Isady) in European Russia yielded a diverse Lopingian (upper Permian) flora including some very peculiar compound ovuliferous cones. Methodology. The micromorphologies of eight specimens of dispersed compound ovuliferous cones-some in organic connection with conifer shoot fragments-are described, and their relationships are tested in a phylo-genetic analysis. Pivotal results. Mutoviaspermum krassilovii gen. et sp. nov. is characterized by a stout main axis with helically arranged ovuliferous scales protected by coriaceous bracts. The polysperms have a peltate structure with an apical whorl of segments fused only in the basal part near the stalk and with a seed scar on each segment. The anatomical connection between M. krassilovii and Quadrocladus-like leaves provides the basis for reassessing the botanical affinities of these taxa. Conclusions. A morphological phylogenetic analysis supports the placement of Mutoviaspermum as an early-diverging genus within Voltziales, although a precise relationship of this genus with other early conifers remains uncertain. Results of this analysis underline the ambiguous position of Quadrocladus and highlight its complex and poorly understood relationship within the Permian conifers.