A STRUCTURAL REINTERPRETATION OF THE ENIGMATIC CARBONIFEROUS MIOSPORE PTERORETIS FELIX & BURBRIDGE 1961 EMEND. NOV.

Abstract

The structure of the enigmatic Carboniferous miospore genus Pteroretis Felix & Burbridge 1961 is reinterpreted based on well-preserved assemblages from Pennsylvanian (Duckmantian-Bolsovian) strata in the Machrihanish Coalfield, Kintyre, western Scotland. The genus is emended herein, and evidence is presented of a proximal operculum to justify assignment of the genus to the Infraturma Epitygmati. The complex arrangement of wings, originally described as being perpendicular to the equatorial margin from pole to pole, are demonstrated to be concentric structures in the equatorial and subequatorial regions. Wings developed on the distal surface commonly form a cuppa structure similar to that developed in Fragilipollenites Konyali 1965 emend. McLean 1997. A comparison is made with Vestispora (Wilson & Hoffmeister 1956) Wilson & Venkatachala 1963, the only other operculate Carboniferous miospore genus. Comparisons are also made with other genera such as Columinisporites Peppers 1964 and Fragilipollenites, which are costate and cuppa-bearing respectively. Previous records of Pteroretis from Europe and North America are reviewed, and indicate a Late Mississippian (Late Viséan-Chesterian) to Mid Pennsylvanian (Bolsovian) age. Paleobotanical evidence suggests a sphenophyllalean origin, with Pteroretis miospores being recovered from the fructifications of several species of Bowmanites Binney 1871.