Obirafructus kokubunii E.F.Pires et Da Rosa in Kajita, Suzuki & Nishida

Plant Fossil Names Registry Number: PFN002517

Act LSID: urn:lsid:plantfossilnames.org:act:2517

Authors: E. F. Pires & Á. A. S. Da Rosa

Rank: species

Genus: Obirafructus Y.Kajita et H.Nishida in Kajita, Suzuki & Nishida

Reference: Kajita, Y., Suzuki, M. H. & Nishida, H. (2021): A Multicarpellary Apocarpous Gynoecium from the Late Cretaceous (Coniacian–Santonian) of the Upper Yezo Group of Obira, Hokkaido, Japan: Obirafructus kokubunii gen. & sp. nov. – Acta phytotaxonomica et geobotanica 72(1): 1–21.

Page of description: 2

Illustrations or figures: figs 1B–D, 2–10, 11D, 12C, D

Name is type for

Types

Original diagnosis/description

Permineralized angiosperm reproductive shoot consisting of a woody axis bearing more than 42 conduplicate follicles in 5 : 8 phyllotaxy. Axis in fruiting stage, more than 57 mm long, 2–5 mm in diam., eustelic; vessels with scalariform perforation plates. Follicles elongate fusiform to falcate, 30–40 mm long, 3 mm in diam., short-stiped, abruptly tapering distally, dehiscing along longitudinal ventral suture; lateral surface transversely striate; cross section nearly round with semicircular dorsal ridge and ventral ridge splits at middle along longitudinal suture. 3-veined, 1 dorsal and 2 on each side of ventral suture. Follicle wall 3-layered; pericarp thin, consisting of an epidermis with actinocytic stomata and hypodermis; mesocarp thick, parenchymatous, vascularized; endocarp composed of fibrous sclerenchyma cells; placenta marginal. Seeds nearly 100, flat, tightly packed in each follicle, in 2 rows, one above the other, bitegmic, anatropous, winged on upper side, semicircular to oval, ca. 2 mm long, 1 mm wide along horizontal plane, ca. 0.6 mm thick at middle; wing fleshy parenchymatous inside, on upper side of main seed body, as thick as nucellar portion, anvilshaped, with narrow marginal extensions horizontally around seed; nucellar portion semicircular to crescentshaped in horizontal plane, rounded columnar in tangential plane at widest middle portion. Seed coat composed of inner and outer layers; inner seed coat mostly 1 cell thick, 3 cells thick around endostome; outer seed coat constituting wing and lower fibrous layer, attached to placenta on winged side, vascularized by a single bundle on upper middle portion of wing to chalazal end of nucellus. Nucellar wall membranous, thickened below endostome to form a nucellar cap.

Etymology

The specific epithet honors Mr. Hakuji Kokubun, who found the specimen.

Stratigraphy

Cretaceous, Upper Cretaceous
Coniacian to Santonian, Haborogawa Formation, Yezo Group

Locality

Japan
Obira, main stream of the Obirashibe River, approximately 44º04′53″N, 141º57′05″E, Hokkaido