Miranthus kvacekii E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN, 2021

Friis, Else Marie, Crane, Peter R. & Pedersen, Kaj Raunsgaard, 2021, Early Flowers Of Primuloid Ericales From The Late Cretaceous Of Portugal And Their Ecological And Phytogeographic Implications, Fossil Imprint 77 (2), pp. 214-230 : 222

Miranthus kvacekii E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN sp. nov.

Text-fig. 7a–e

H o l o t y p e. S170157 (Mira sample 100; figured Textfig. 7a–e).

P l a n t F o s s i l N a m e s R e g i s t r y N u m b e r.

PFN002673 (for new species).

R e p o s i t o r y. Palaeobotanical Collections, Swedish

Museum of Natural History , Stockholm, Sweden ( S) .

E t y m o l o g y. In commemoration of Zlatko Kvaček and his outstanding contributions to Cretaceous and Cainozoic angiosperm palaeobotany.

T y p e l o c a l i t y. Mira (40° 25ʹ N; 08° 44ʹ 15ʺ W), about 25 km south of Aveiro , District of Coimbra, Portugal .

T y p e s t r a t u m a n d a g e. “Argilas de Vagos”,

Late Cretaceous (Campanian/Maastrichtian).

D i a g n o s i s. As for the genus with the following addition: Epidermis of pedicel and outer (abaxial) epidermis of calyx with closely spaced, robust, stiff trichomes.

D i m e n s i o n s. Length of flower excluding pedicel and corolla: 0.8–1.0 mm; diameter: 0.7–1.0 mm. Length of flower bud with corolla, but excluding the pedicel: 1.5 mm.

D e s c r i p t i o n a n d c o m m e n t s o n t h e

s p e c i e s. The species is based on a single flower bud discovered with Miranthus elegans in the Mira mesofossil flora ( Text-fig. 7a–e ). The individual floral parts are strongly appressed and somewhat distorted, which impedes a full understanding of the floral structure and organization (Textfig. 7b–e). However, the androecium clearly consists of five stamens. The stamens also apparently alternate with the sepals and are obhaplostemonous ( Text-fig. 7d, e ). The stamen filaments appear to be fused to the corolla for part of their length, while the anthers are free from the corolla and from each other. Alternating with the filaments are filament-like structures. These are not as distinct as the stamen filaments and interpreted as staminodes ( Text-fig. 7e ). The flower bud is similar to Miranthus elegans in its characteristic free, dome-shaped placenta ( Text-fig. 7b, c ) and semi-inferior ovary ( Text-fig. 7b, c ), but differs in having short, densely spaced trichomes on the outer surface of the calyx lobes, particularly along the margins ( Text-fig. 7a ). Although scattered trichomes and trichome basis are observed in Miranthus elegans , the trichomes are much finer and less densely spaced.

Figures

Text-fig. 7. SEM (a) and SRXTM (b–e) images of Miranthus kvacekii sp. nov.; Mira locality, Portugal. a: Lateral view of flower bud showing corolla lobes extending beyond calyx; note surface of pedicel, calyx and corolla with small equiaxial epidermal cells and indumentum of densely spaced, short stiff trichomes. b, c: Longitudinal sections through floral bud in two directions perpendicular to each other (a, orthoslice yz1024; b, orthoslice xz0950) showing corolla (co), calyx (ca), stamens (st) and semi-inferior ovary with thin ovary wall (ow) and central mushroom-shaped globose placenta (pl) bearing numerous ovules (ov). d, e: Transverse sections through floral bud above placenta (d, orthoslice xy0915; e, orthoslice xy1095) showing calyx (ca), corolla (co), ovary wall (ow) and ovules (ov); yellow outlines indicate the positions of anthers (d) and filaments (e); orange outlines indicate the position of three of the possible staminodes. Specimen, Mira 100-S170157 (a–e, holotype). Scale bars = 600 µm (a–c), 300 µm (d, e).