Atlantocarpus E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN, 2020

Friis, Else Marie, Crane, Peter R. & Pedersen, Kaj Raunsgaard, 2020, Multiparted, Apocarpous Flowers From The Early Cretaceous Of Eastern North America And Portugal, Fossil Imprint 76 (2), pp. 279-296 : 286-287

Genus Atlantocarpus E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN gen. nov.

T y p e. Designated here. Atlantocarpus virginiensis

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

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.

PFN001600 (for new genus).

E t y m o l o g y. From the occurrence of the genus on both sides of the Cretaceous North Atlantic.

D i a g n o s i s. Floral structure bracteate, pedicellate and structurally bisexual, with a multiparted perianth, androecium and gynoecium. Floral receptacle elongate conical. Ovary superior lacking a hypanthium. Perianth of about 15 tepals in two or more series. Tepals with broad rhombic bases. Androecium of about 15 free stamens in two or more series. Gynoecium apocarpous, of about 40 to 50 carpels arranged spirally along the elongated receptacle. Style lacking, stigmatic region extended. Carpels apparently ascidiate.

C o m m e n t s o n t h e g e n u s. Atlantocarpus is distinguished from Mugideiriflora and Lambertiflora by its strongly elongated receptacle that bears only a few tepals. It also differs from previously described Cretaceous floral structures that also have a strongly elongated receptacle ( Archaeanthus linnenbergeri DILCHER et P.R.CRANE; Choffaticarpus compactus and Reyanthus lusitanicus ) in its fewer floral parts. The specimen of Atlantocarpus sp. described here from the Buarcos locality was illustrated previously in association with fruits of Anacostia E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN ( Friis et al. 1997: fig. 10A–C). Another specimen also associated with Anacostia is from the Puddledock locality and strongly compressed ( Friis et al. 1997: fig. 6A–E). This specimen is also multicarpellate and apocarpous and was linked with fruits of Anacostia E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN based on abundant Anacostia - type pollen at the base of the floral receptacle. This specimen is similar to Atlantocarpus in general organization. It is, however, distinguished from Atlantocarpus by its larger size and greater number of carpels and we here refer to this fossil as Anacostia ? sp. ( Text-fig. 6a, b ). Another multicarpellate and apocarpous floral structure from Puddledock ( Text-fig. 6c ) is similar to Anacostia ? sp. but three-dimensional. Possibly this specimen and Anacostia ? sp. represent different developmental stages of the same kind of plant. Unfortunately, there are no cellular details or pollen that could link the specimens of Atlantocarpus to Anacostia . For further discussion and references, see Discussion.

Figures

Text-fig. 6. Scanning electron micrographs of multicarpellate and apocarpous floral structures from the Early Cretaceous Puddledock locality, Virginia, USA (a, b: PP43701, Puddledock sample 001; c: PP43000x, Puddledock sample 073). a) Anacostia? sp., strongly compressed, elongated receptacle with spirally arranged carpels (red dots; not all shown); note larger size compared to the other floral structures; b) Numerous Anacostia type pollen grains in proximal view from the base of floral structure in (a); note graded reticulum over the proximal pole of the pollen grains; c) Elongated receptacle with numerous carpels in a spiral arrangement, possibly representing an earlier developmental stage of Anacostia? sp. Scale bars = 1 mm (a, c), 10 µm (b).