Cupule-bearing cones of Jarudia (Doyleales) and associated leaves from the Early Cretaceous of the New Siberian Islands, Arctic Russia

Abstract

A new species of cupule-bearing seed cone assigned to Jarudia (Doyleales) is described from the Lower Cretaceous (Aptian–Albian) Balyktakh Formation of Kotelnyi Island in the New Siberian Islands. The new species, Jarudia borealis sp. nov. is an elongated, cylindrical seed cone consisting of a main axis with helically arranged, densely spaced bract-cupule axis complexes, each of which terminates in a single incurved cupule. Cupule-bearing stalks are thin proximally where they are fused with a narrow, elongated bract. Above, they are free from the bract, gradually widen toward the tip and are curved adaxially relative to the main axis. Each cupule is formed by the wide flattened distal part of the cupule stalk, one median and two lateral flaps, and is quadrangular in transverse section. The flattened cupule stalk and three flaps are fused at the apex of the cupule but are free toward the base. Micro-CT scans reveal that most cupules are empty, but maceration of remaining carbonaceous material produced pieces of the cupule cuticle, as well as fragments of the nucellar cuticle and megaspore membrane. Stomata, occasionally present in the outer epidermis of the cupules, are haplocheilic, with 5–8 subsidiary cells. The megaspore membrane is two layered comprising a foot layer and branched, interconnected bacula. The cupule-bearing cones of Jarudia borealis sp. nov. occur closely associated with numerous remains of linear leaves described as Phoenicopsis arcticus sp. nov., as well as rare leaf fragments of Pityophyllum sp. and Ginkgoites sp.