We describe a new miospore genus Maiaspora gen. nov. from the upper Visean (middle Mississippian) of the southern wing of Moscow Syneclise (European Russia). A combination of methods (optical light microscopy (LM), scanning-electron microscopy (SEM), confocal laser microscopy (CLSM) and image-analysis) to study the same individual miospore specimens revealed a remarkable sculptural type for which we propose the new term ‘metareticuloid’. Metareticuloid sculpture is defined as a complex arrangement of muri with apiculate elements, polygonal lumina and circular scrobiculae at the base of the lumina. The discovery of fossil spores with metareticuloid sculpture allows the recognition of clear morphological differences between microreticulate and foveolate sculptures which palynologists have historically had difficulty in separating. Virtual cross-sections provided by CLSM show that miospores with metareticuloid sculpture display perfectly-preserved, funnel-shaped tunnels (like a gallery of cave stalactites) in the deep exospore. In contrast, miospores with microreticulate or reticulate and partly-vermiculate sculpture lack such vertical tunnels (termed scrobiculae). The morphology of Maiaspora gen. nov. is considered in comparison with Microreticulatisporites (Knox non sensu Potonié et Kremp) Bhardwaj emended Oshurkova, Pseudoreticulatispora Bharadwaj et Srivastava emended Price et Foster, Vadaszisporites (Deák et Combaz) emended Juhasz, Foveosporites Balme, Foveotriletes van der Hammen ex Potonié, Garotriletes Singh et Singh, Assamiasporites Mehrota et Sah, Margotriletes Mehrota et Sah. The morphological conceptions of Microreticulatisporites and Foveotriletes are reinterpreted by numerical typification. The adaptative significance of metareticuloid sculpture is discussed in relation to modern and fossil spores, and in terms of harmomegathic mechanisms of angiosperm pollen.
Maiaspora 54 Virtual
Series of slides are provided by confocal scanning electron microscopy. Miospore specimen 54 of Maiaspora panopta.
Maiispora 40 Virtual
Series of slides are provided by confocal scanning laser microscopy. Miospore specimen 40 of Maiaspora panopta.
Microreticulatisporites concavus 1 Virtual
Series of slides are provided by confocal scanning laser microscopy. Miospore specimen 1 of Microreticulatisporites concavus.
Microreticulatisp-1 Virtual.avi
Microreticulatisporites concavus - 73 Virtual
Series of slides are provided by confocal scanning laser microscopy. Miospore specimen 73 of Microreticulatisporites concavus
Microreticulatisp-2 Virtual.avi
Figure 19 (Supplemental)
SEM photomicrographs of Maiaspora panopta gen. et sp. PIN RAS. A, miospore specimen 336-13, distal aspect; B, miospore specimen 336-17, distal aspect; C, miospore specimen 336-15, distal aspect; D, miospore specimen 336-16, proximal aspect; E, miospore specimen 336-14, distal aspect; F, miospore specimen 336-41, distal aspect; G, miospore specimen 336-18; proximal aspect; H, miospore specimen 336-20; proximal aspect; I, miospore specimen 336-22, proximal aspect; J, miospore specimen 336-21, distal aspect; K, miospore specimen 336-19, distal aspect; L, miospore specimen 336-23, proximal aspect. Scale bar = 10 µm.
Figure 20 (Supplemental)
SEM photomicrographs of Maiaspora panopta gen. et sp. PIN RAS. A, miospore specimen 336-37, distal aspect; B, miospore specimen 336-43, proximal aspect; C, miospore specimen 336-38, proximal aspect; D, miospore specimen 336-33, distal aspect; E, miospore specimen 336-32, distal aspect; F, miospore specimen 336-31, equatorial-proximal aspect; G, miospore specimen 336-40, equatorial aspect; H, miospore specimen 336-36, distal-equatorial aspect; I, miospore specimen 336-38, proximal aspect. Scale bar = 10 µm.
Figure 21 (Supplemental)
SEM photomicrographs of Microreticulatisporites concavus (A–C), Maiaspora panopta gen. et sp. (D, F–I), and Microreticulatisporites sp. (E) PIN RAS. A, miospore specimen 336-50, proximal aspect, BSE mode; B, miospore specimen 336-51, distal aspect; C, miospore specimen 336-52, equatorial-proximal aspect; D, miospores specimen 336-53, distal aspect; E, miospore specimen 336-54, proximal aspect; F, miospore specimen 336-55, equatorial aspect; G, miospore specimen 336-56, proximal aspect; H, miospore specimen 336-57, proximal aspect; I, miospore specimen 336-58, distal aspect. Scale bar = 10 µm.
Figure 22 (Supplemental)
CLSM virtual reconstructions of Maiispora panopta gen. et sp. nov showing fluorescent exospore and non-fluorescent vertical tunnels on equatorial margin. A-C, miospores specimen 336-52; A, surface mode, proximal aspect; B, transparent mode, virtual plane close to proximal focus, tunnels visible; C, virtual plan close to distal focus; D-F, miospore specimen 336-29; D, surface mode, distal aspect; E, transparent mode, virtual plane close to proximal focus, tunnels visible; F, virtual plane close to distal focus; G-I, miospore specimen 336-53; G, surface mode, proximal aspect; H, transparent mode, virtual plane close to distal focus, tunnels visible; I, virtual plane close to proximal focus. Scale bars = 5 µm.
Source_ file_morphometry
The data file contains a series of measurements of area, Wadell`s diameter of lumina, scrobiculae, a distance of the mass centres, muri width, the coefficient of variation, ratio w\W. All measurements were provided on detailed SEM micrographs of miospore specimens of Maiaspora panopta gen. et sp. nov, Microreticulatisporites concavus, and SEM micrographs of comparable in situ spores.