摘要
本文报道的Pagiophyllum属4新种,是在对它们的角质层构造进行了研究的基础上建立的,标本产自浙东新昌县苏秦村附近的馆头组,共生的植物化石尚有Ruffordia goepperti, Zamiophyllum buchianum, Pseudofrenelopsis parceTflogoso, P. papillosa, Cupressinocladus elegans等;另在苏秦村南面镜岭的相当层位中还找到双壳类化石Plicotounio(P.)zheijiangensts。这些化石都表明馆头组的地质时代为早白垩世。
This paper deals with four new species of Pagiophyllum, paying particular attention to the characteristics of the cuticular structure. The specimens are obtained by the author from the Guantou Formation of Xinchang County, Zhejiang Province. Their associated fossil plants, according to the accumulated data from determination of fossil plants brought to the Institute and the published material (Chow et Tsao, 1979; Gu 1980; Cao, 1989), have been recognized as: Ruffordia of. goepperti (Dunker), Onychiopsis of. elongata (Geyler), O. psilotoides (Stockes et Webb), Cladophlebis of. browniana (Dunker), Cl. of. dunkeri (Schimper), Gleichenites sp.,? Sphenoperis fottoni Seward, Zamiophyllum buchianum (Ett.), Pseudofrenelopsis parceramosa (Font.) Watson, P. papillosa (Chow et Tsao), Cupressinocladus elegans (Chow),? Cupressinocladus sp., Brachyphyllum sp., etc., indicating that the Guantou Formation belongs to the Early Cretaceous or middle Early Cretaceous in age.
Description of species
Pagiophyllum delicatum sp. nov.
(Pl. Ⅳ, figs. 8—10)
Shoots delicate in habit, appearing to be spirally branched. Ultimate shoot linear, straight, arising at an angle of about 35° from penultimate shoot. Axis less than Imm wide; leaves forming a loose simple helix. Leaf base cushion normally concealed; free leaf borne at its apex, projecting radially at an angle of about 50° to the axis, lingulate in surface view, somewhat recurred, about 1.5mm long by about 0.7mm wide near middle. Substance of leaf thick; adaxial surface of leaf concave and abaxial surface very convex. Margin entire not scarious.
Lower cuticle thick but fragile, consisting of polygonal or elongately polygonal cells in irregularly longitudinal arrangement; anticlinal cell walls thick and straight; cell surface bearing a large papillae at center. Stomata rare and scattered in the ordinary cells. Subsidiary cells thickly cutinized and forming a round ring surrounding the stomatal pit. Guard cell not shown.
This species looks like the below-mentioned Pagiophyllum sthenopapillae, but the former has a delicate habit with longer, more open and looser leaves than the latter. Besides, they are also some- what different from each other in the outline of the epidermal cells and the size and distribution of papillae. Pagiophyllum obtusior sp. nov.
(Pl. Ⅰ)
Uppermost part of a penultimate shoot spirally branched. Ultimate shoot linear, straight, about 1.7cm long and about 4mm wide; axis about 1mm wide, arising at an acute angle from the main shoot. Leaves helically arranged, diverging from axis at an angle of about 40°, overlapping and usually concealing the basal cushion of leaves above, nearly digitate, curving slightly forwards; larger leaves 4mm long, about 1.5mm wide at the base, tapering evenly to obtuse apex. Substance of leaf very thick, about half the width in thickness; adaxial surface slightly concave and abaxial surface very convex, with no ridge along mid-line.
Cuticle thick. Epidermal cells of both surface similar, normally long-rectangular or elongatepolygonal in longitudinal arrangement, 25—90μm in length and 20—40μm in width; marginal cells much narrower than others. Surface wall unevenly cutinized, always with a hollow papilla at the upper(?) end; inner surface showing the entrance of the hollow papilla with numerous radiate striations; anticlinal cell walls prominent and interrupted. Stomata irregularly scattered on the abaxial surface of leaf, separated by 6-7 ordinary epidermal cells, but rare on the adaxial surface. seemingly with 6-7 subsidiary ceils forming a cutinized ring arround the stomatal pit; details about stomata unknown. No guard cell preserved.
This species is characterised by its nearly digitate leaf shape, more or less rectangular epidermal cell outline, peculiar papilla and interrupted anticlinal cell wall, and can be distinguished from all known species of Pagiophyllum and other species described, under this generic name in the present paper.
Pagiophyllum sthenopapillae sp. nov.
(Pl. Ⅱ; Pl. Ⅲ; Pl. Ⅳ, figs. 1—7)
A fragmentary shoot with uhimate shoot small and short, only about 1—1.5mm in width and about 7mm in length (incompletely preserved), arising on all sides at an angle of about 45° from penultimate shoot. Leaves small, scaly, 1—2mm long, with a maximum width of about 0.5—1.5mm at base, tapering to round apex; apex somewhat curving forwards, arranged in a crowded simple helix, diverging from axis at a large angle, overlapping and concealing basal cushion of leaves above. Substance of leaf rather thick; adaxial surface of leaf concave anl abaxial surface convex but with no ridge along mid-line.
Lower cuticle very thick. Outer surface covered with very strong solid papillae; inner surface ornamented with faint longitudinal stiations. Epidermal cells rectangular or nearly rectangular in longitudinal arrangement, 25—60μm long, 15—25μm wile, usually becoming more or less square at leaf base. Anticlinal cell walls thick and straight. Stomata irregularly distributed over whole leaf and cushion, rounded, about 50—70μm in diameter, sunken, with overhanging papillae of subsidiary cells around and inside the stomatal pit. Subsidiary cells 6 or 7 in number, thickened, forming a round ring surrounding the stomatal pit. No guard cell preserved. Upper cuticle silnilar to lower one, but slightly thinner, with rare stomata; its epidermal cells more irregular in shape, mostly polygonal, ahnost without papillae. Hypodermal cells marked by thin ridges of cuticle, elongated and with pointed ends.
The important features of this species lie in the smaller and shorter ultimate shoots, scaly and crowdedly spirally arranged leaves, very strongly papillate surface of cuticle with well-developed papillae around and inside the stomatal pit. The sterile shoots of the well-known Sphenolepis kurriana from the Lower Cretaceous strata of Europe and North America closely resemble those of the present species in shape, but they are quite different in cuticle. This species is very similar both in shape and cuticle to the other two species of Pagiophyllum, Pagiophyllum delicatum and P. xinchangense described in this paper, but it differs from the former as mentioned above and from the latter as discussed below.
Pagiophyllum xinchangense sp. nov.
(Pl. Ⅴ)
Part of shoots appearing to be spirally branched. Ultimate shoots about 2mm wide, arising at a small angle. Leaves smaller, scaly, about 2mm long and 2ram wide at base, tapering to round apex, crowdedly arranged in simple helix, diverging from axis at a smaller angle, overlapping and concealing basal cushion of leaves above. Substance of leaf very thick; leaf's adaxial surface concave and abaxial surface very convex but with no ridge along mid-line.
Lower cuticle very thick; outer surface of cuticle bearing little developed papillae (only shown under SEM). Epidermal cells short, rectangular or polygonal in shape, 25—70μm long and 20—40μm wide; anticlinal cell walls straight and thick; periclinal cell wails with many faint striations on inner surface, adjacent ones forming a somewhat rounded corner. Stomata irregularly disposed, circular, about 50—70μm in diameter; subsidiary cells with 5 or 6 in number, making up a strongly, evenly thickened ring. Upper cuticle a little thinner than lower one; stomata rare; epidermal cells generally rectangular in outline, more regularly arranged in longitudinal rows, about 20—50μm long and 15—25μm wide. Hypodermal cells unknown.
In the general shape of shoots and leaves as well as the cuticular feature, this species bears a considerable resemblance to Pagiophyllum sthenopapillae. After a careful comparison of the specimens, the writer has come to the conclusion that they should belong to two distinct species, because in the former, the shoot is stouter, the leaf is larger and thicker, the epidermal cells of the lower cuticle are generally shorter and rectangular in shape and slightly large in size, forming a more or less rounded corner, the papillae are less developed and the epidermal cells of the upper cuticle are more regular both in shape and arrangement; by all of these characteristics it can be distinguished from the latter.
出处
《古生物学报》
CAS
CSCD
北大核心
1991年第5期593-600,667-671,共8页
Acta Palaeontologica Sinica
关键词
坚叶杉属
早白垩世
馆头组
浙江
ZheJiang, Early Cretaceous, Guantou Formation, Pagiophyllum
