Kasicarpa melikianii

Name

Kasicarpa melikianii

Rank

Species

Generic Name

[Genus] Kasicarpa

Authors (Pub.)

Maslova N. P. Golovneva L. B. Tekleva M. V.  

Publication

Infructescences of Kasicarpa gen. nov. (Hamamelidales) from the Late Cretaceous (Turonian) of the Chulym-Yenisey depression, Western Siberia, Russia [2005/12]

Journal

Acta Palaeobotanica

Volume

45

Issue

2

Page number

124

Year

2005

Fossil Status

infructescences

Stratigraphy

Turonian

Location

Kas river, Chulym-Yenisey depression, Krasnojarsk territory, Russian Federation

Paleoregion

Eurasia (W Siberia)

Data for Holotypus

Repository

Tomsk State University, Palaeontological Museum, Tomsk, Russian Federation

Repository Number

29/8b

Num

fig. 3

Pub.

Infructescences of Kasicarpa gen. nov. (Hamamelidales) from the Late Cretaceous (Turonian) of the Chulym-Yenisey depression, Western Siberia, Russia [2005/12]

Diagnosis

Compound infructescence consists of a ribbed axis, 2 mm thick, bearing several alternate heads of about 5 mm in diameter. Up to six heads are preserved on one axis. The heads are sessile, irregularly distributed along the axis at a distance of 2 to 8 mm, more densely crowded towards the apex. The head consists of a central rounded receptacle 1 mm in diameter and flowers/fruits of various developmental stages, from immature carpels to nearly ripe fruits, attached radially to the axis and tightly adpressed to each other. There are rounded scars of various diameters left by the shed fruits. The larger scars obviously mark ripe fruits. The approximate number of flowers per head is 30–40. The length of the flowers is 0.9–1.1 mm, the width ranges from 0.4 to 0.7 mm depending on their ripeness. The mature fruits are obconical, widening towards the top, flattened. Carpels at the earlier stages of development are cylindrical, of nearly equal width throughout. The flower consists of a well-developed perianth and a single carpel. The perianth is roughly equal or somewhat longer than young carpel and about 2/3 of the ripe fruit, with different inner and outer tepals. The cuticle of the outer tepals shows strongly cutinized rectangular or wedge-shaped cells 20–35 µm long 8–10 µm wide, arranged in more or less regular rows. Surface cells of the inner tepals are thinly cutinized, showing slightly undulate anticlinal walls. The ripe fruits are obconical, lacking stylodia. The cuticle of exocarp is folded, formed of strongly cutinized polygonal cells varying in outlines and dimensions, about 13–18 µm long, with undulate anticlinal walls. Basal part of fruit is devoid of stomata, that are rather numerous distally. The stomata are anomocytic, with 5–6 irregular subsidiary cells. The inner cuticle (of endocarp wall) shows nearly squar to rectangular cells, occasionally triangular or polygonal, arranged in longitudinal rows. The anticlinal and periclinal cell walls are equally heavily cutinized; the plaques of epicuticular wax are clearly seen. The fruit contains a solitary and orthotropous seed, with hilum and micropyle on the opposite ends, elongate-ovate, 0.9 mm long, 0.35 mm wide shortly above the base, tapering gradually to the micropylar end and more abruptly to the chalazal end. The micropyle is morphologically distinct as a slender beak shortly protruding from beneath the epidermis. The chalaza is relatively massive and darker stained. The hilum is truncate, flat. The seed is transparent, showing at least three cell layers over most of the body. The epidermis is a colorless single-cell layer of uniform thickness over most of the body, decreasing over chalaza and toward the micropyle, where it is interrupted by the apical beak. The epidermal cells are swollen, hemispherical to nearly spherical, apparently mucilaginous. The evidence of a cuticle is not clear. Over the hilum facet, the epidermis is reduced and the outer layer consists of the radial elongate columnar cells that are discernible over the chalaza, vanishing above. A thin transparent single-cell layer beneath the epidermis consists of slender helically thickened sclereids that are arranged parallel to the long axis of the seed. The darker inner layer shows longitudinal rows of elongate to fusiform cells about 20–30 µm long, 3–5 µm wide, containing small spherical granules, which correspond to aleurone grains of endosperm in many angiosperm seeds. Accordingly, the innermost visible layer is interpreted as the starch-storing aleurone layer of a thick endosperm. The pollen grains adhering to the surface of the carpels are tricolpate, elliptical, the polar axis is 9.0–11.0 µm, the equatorial diameter 14.0–17.5 µm. The colpi are very long, nearly reaching to the poles. Some pollen have colpi varying in length, with two longer and one shorter, from 3.0 to 7.0 µm. The exine is reticulate. The lumina vary in shape (rounded to elongate) and size, but not differentiated between the mesocolpia and the margins of colpi, which are indistinctly marked. In the TEM, the sectioned pollen wall is 1.29 µm thick all over the mesocolpia, showing a perforated tectum of uniform thickness about 0.36 µm. The infratectal layer is columellate. The columellae are nearly cylindrical, 0.33 µm high, 0.14 µm wide. The foot layer is distinct all over the non-apertural region, 0.36 µm thick. Under it, there is an electronically less dense, homogenous layer, which probably represents the endexine. This layer is about 0.24 µm. The ectexine decreases sharply towards the colpi and wedges out at their margin. The apertural region consists of the supposed endexine alone.