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WIERER, Johann Franz:Vergleichende Untersuchungen an Megasporenvergesellschaftungen der alpinen und germanischen Mittel- und Obertrias1998. [in German] – 176 pp., 21 figures, 19 tables, 44 plates. ISBN 978-3-931516-18-5 Euro 40.00 |
Megaspore assemblages of Middle to Upper Triassic age from the Alpine and German realm are described. The stratigraphic value of megaspores and the feasibility of supra-regional correlations are demonstrated.
Investigations in the Dolomites of Southern Tyrol (Italy), comprising Wengen Formation, Cassian Formation and Raibl Group with a stratigraphic range from Longobardian (Upper Ladinian) to Julian (Middle Carnian) Substage, revealed a constant, individual-rich megaspore content. In the Longobardian Substage a total of 22 megaspore species is present. The Longobardian-Cordevolian boundary is marked by a decrease in megaspore diversity, caused by climatic and environmental changes. Out of 22 species known in the Longobardian only six species persist in the Cordevolian Substage and only four species are indicated in the Julian Substage. This newly described megaspore assemblage is named Horstisporites selaginelloides-assemblage (Assoziation).
Correlation with the Dijkstraisporites beutleri-megaspore assemblage of German Lettenkeuper (Longobardian) is possible for the Longobardian part of the Horstisporites selaginelloides-assemblage, based on some rare species common to both assemblages.
Yet, concerning the widespread, typical species, the Horstisporites selaginelloides-assemblage shows a quite independent composition. Probably most of the individual-rich species are endemic in the volcanic and carbonatic islands of Southern Alpine Longobardian to Julian.
The Dijkstraisporites beutleri-assemblage was investigated in Southern Germany (Lettenkeuper of Franconia and Baden-Württemberg) for the first time and fits well with the data so far known from the German Basin. 30 species of megaspores are described.
The Dijkstraisporites beutleri-assemblage (German Lettenkeuper, Longobardian) differs markedly from the Narkisporites harrisi-assemblage of German Reed Sandstone (Schilfsandstein, Julian). Supplementary to existing data, samples from Franconian Reed Sandstone were investigated, containing 15 species of megaspores.
The Narkisporites harrisi-assemblage of German Reed Sandstone shows wide conformity and therefore allows good comparison with the megaspore assemblage of Lunz (s.l.) - and Opponitz Beds (Julian-Tuvalian Substage) in the area of Lunz am See (Northern Calcareous Alps, Austria), investigated in detail for the first time. This megaspore assemblage, named Echitriletes digitiformis-Radosporites planus/spinosus-assemblage contains 32 species of megaspores, of which 20 are known from German Reed Sandstone. Some species, so far reported only from German Lettenkeuper (Longobardian) also occur in the Julian of Lunz. The continued existence of those species outside the German Basin is considered as an effect of favourable climatic and/or environmental conditions and is of no influence to the stratigraphic position of Lunz Beds.
The Julian megaspore assemblages of Lunz and German realm are connected with the Julian part of the Horstisporites selaginelloides-assemblage only by the long-lived species Verrutriletes ornatus REINHARDT & FRICKE 1969. Concerning the Cordevolian part of the Horstisporites selaginelloides-assemblage a correlation with the German and Lunz deposition area is not possible due lack of secure comparable data.
The megaspore species under consideration are described comprehensively using SEM-data and deliminated from similar species. The results of former investigators are reconsidered. The occurence of small and large forms within several megaspore species and of aberrant dehiscence marks are discussed.
According to the new rules of the I. C. B. N. the diagnoses of new species must be given in English or Latin. Following this rule, the diagnoses of new genera and species are given in the English summary. Also other taxonomical changes (recombinations, emendations) are listed here.
The morphographical system is extended by the infraturma Semiornati nov. infrat. (see page 85)
Diagnosis: Azonotrilete spores, ornamentation mainly restricted to the area, consisting of grana, verrucae, coni, rugulae or similar low elements not overtopping or obscuring the trilete mark. Trilete mark well developed but not raised to form a trifolium or split up in trichomes.
Within the infraturma Semiornati n. infrat. the genus Breviornatisporites n.gen. (see page 86) is described.
Genotypus: Breviornatisporites asper n.gen. n.sp. (see diagnosis of species)
Diagnosis: Azonotrilete megaspores, 175-600 µm in diameter, rounded to triangular in outline. Trilete rays well developed, length 0,6-1 of spore radius. Ornamentation restricted to the proximal hemisphere, especially the area, consisting of grana, verrucae, coni, rugulae or similar low elements, eventually reaching up on the flanks or to the vertex of the trilete rays. Curvaturae missing or ± well developed. Distal hemisphere smooth.
Breviornatisporites asper n.gen. n.sp. (see page 86-87)
Diagnosis: Azonotrilete megaspores, subtriangular in outline, diameter 175-380 µm. Trilete rays straight or slightly bent, 19-33 µm high, 10-22 µm wide, extending 0,75-0,85 of spore radius. Fine granulose ornamentation restricted to the area or even the apical region and the basal part of the trilete rays. Granulae rounded in outline, only slightly elevated, diameter 2-5µm. Spore surface outside the area smooth.
The spore wall consists of a thick, granulose exoexine and a membraneous intexine. Thickness of wall 12-14 µm.
Breviornatisporites variolatusn.gen. n.sp. (see page 87)
Diagnosis: Azonotrilete megaspores, subtriangular in outline, diameter 280-360 µm. Trilete rays straight or slightly bent, raising towards the apex, 31-40 µm high, 17-22 µm wide, extending 0,8-0,9 of spore radius, covered with verrucae except the smooth, rounded ends, thus gaining an irregular, nodular appearance.
Area ornamented with hemispherical, blunt conical or elongated, slender verrucae, rounded to elongated in outline, sometimes joint at the base, forming short ridges orientated radially towards the apex. Curvaturae missing. Surface outside the area smooth or slightly wavy. The spore wall consists of a thick, granulose exoexine and a membraneous intexine. Thickness of wall 8-12 µm.
Breviornatisporites verrucosus n.gen. n.sp. (see page 87-88)
Diagnosis: Azonotrilete megaspores, rounded to subtriangular in outline, diameter 245-430 µm. Trilete rays well developed as broad, mostly sraight bands, 16-24 µm high, 16-26 µm wide, extending 0,8-0,9 of spore radius, ends of trilete rays partly with nodular thickenings.
Area and flanks of trilete rays densely covered with hemispherical verrucae, 5-16 µm in diameter, 5-8 µm high. Verrucae in places joint to form elongate, nodular structures. Area often slightly sunken. Curvaturae missing. Spore surface outside the area smooth.
Thickness of wall 14-17 µm. Exoexine granulose, intexine not clearly discernible.
Formal recombinations with the genus Breviornatisporites n.gen.:
– Breviornatisporites pusillus (LI & BATTEN 1987) comb. nov.
Basionym: Maexisporites pusillus LI & BATTEN in: LI WENBEN, BATTEN, ZHANG DAHUA & ZHANG LIANGDE 1987, p. 122, pl. 1, fig. 2, 5
– Breviornatisporites inflatus (FUGLEWICZ 1973) comb. nov.
Basionym: Hughesisporites inflatus FUGLEWICZ 1973, p. 441-442, pl. 30, fig. 1
– Breviornatisporites pustulatus (MARCINKIEWICZ 1962) comb. nov.
Basionym: Hughesisporites pustulatus MARCINKIEWICZ 1962, p. 478, 493, pl. 12, fig. 4
– Breviornatisporites simplex (FUGLEWICZ 1977) comb. nov.
Basionym: Hughesisporites simplex FUGLEWICZ 1977a, p. 423, pl. 40, fig. 4
– Breviornatisporites tumulosus (MARCINKIEWICZ 1976) comb. nov.
Basionym: Hughesisporites tumulosus MARCINKIEWICZ 1976, p. 197, pl. 29, fig. 7
– Breviornatisporites variabilis (DETTMANN 1961) comb. nov.
Basionym: Hughesisporites variabilis DETTMANN 1961, p. 76, pl. 1, fig. 15-20, pl. 2, fig. 1
– Breviornatisporites ionthus (HARRIS 1935) comb. nov.
Basionym: Triletes ionthus HARRIS 1935, p. 166-167, pl. 26, fig. 8, text fig. 52e-g
Genus Globulosporites n.gen. (see page 70)
Genotypus: Globulosporites ruboides n.gen.n.sp. (see diagnosis of species)
Diagnosis: Azonotrilete megaspores, trilete mark weakly to strongly developed, curvaturae missing or ± well developed. The whole spore surface densely covered with small, ganulae-like sculptural elements. Additionally bigger, globular elements, also densely covered with small granulae-like appendages occur aranged in groups or randomly spread over the spore surface.
Globulosporites ruboides n.gen. n.sp. (see page 70-71)
Diagnosis: Azonotrilete megaspores, rounded to subtriangular in outline, diameter 170-360 µm. Trilete rays weakly developed, 611 µm high, 4-6 µm wide, reaching 0,35-0,55 of spore radius, lowering markedly towards the ends. Curvaturae absent. The whole spore surface and the flanks of trilete rays densely covered with very small, granulae-like sculptural elements. Under high magnification this appendages appear club-shaped, slightly elongated with thickened, rounded ends (length 2-3 µm, diameter 1-2 µm). Additionally globular appendages 6-18 µm in diameter occur, arranged in groups or randomly spread over the whole spore surface. They are densely ornamented with small club-shaped appendages, similar to those covering the exine but shorter and more compact, thus giving the globular appendages the naming, blackberry-like appearance. The globular appendages are not directly fixed on the spore surface but rest on groups of small pillar-shaped baculae. Therefore they are raised above the level of the small, granulae-like sculptural elemets of the exine.
The spore wall is 6-8 µm thick and homogenous without discernible stratification or ultrastructure.
Trileites lunzensis n.sp. (see page 63-64)
Diagnosis: Azonotrilete megaspores, rounded to subtriangular in outline, diameter 380-690 µm. Trilete rays in most cases straight, rarely slightly sinuous, 18-28 µm high, 17-24 µm wide, extending 0,5-0,6 of spore radius, gradually lowering towards the ends. Ends of trilete rays pointed, in some cases widened (?secondary effect). Vertex smooth, rounded. Curvaturae absent.
Spore surface smooth to faintly granulose/spongy in higher magnification. Thickness of wall 17-20 µm, exoexine granulose, intexine not clearly discernible.
Trileites nanus n.sp. (see page 65-66)
Diagnosis: Azonotrilete megaspores, rounded to triangular in outline, diameter 180-310 µm. Trilete rays weakly developed, straight or slightly bent, 8-14 µm high, 6-10 µm wide, extending 0,7-0,8 of spore radius, vertex rounded, smooth. Curvaturae absent. Spore surface smooth except secondary irregular pits.
Verrutriletes kozurii n.sp. (see page 71-72)
Diagnosis: Azonotrilete megaspores, rounded in outline, diameter 195-360 µm. Trilete rays well developed, with rounded, ± broad vertex, straight to slightly winding, 20-30 µm high, 18-28 µm wide, extending 0,7-0,8 of spore radius. Curvaturae formed by smooth or slightly knobby ridges, 10-15 µm high and wide.
Spore surface densely covered with low to hemispherical verrucae, rounded to oval in outline, diameter 15-25 µm. Thickness of wall 10-12 µm, exoexine spongiose, intexine membraneous.
Remarks: Verrutriletes kozuriin.sp. includes megaspores formerly described as Verrutriletes minor KOZUR 1973 ex MARCINKIEWICZ 1978 (see BATTEN & KOVACH 1990, p. 146). This naming is invalid, because no holotypus is given, moreover Verrutriletes minor KOZUR 1973 ex MARCINKIEWICZ 1978 is a homonym of Verrutriletes minor (FADDEEVA 1965) KOZUR 1973.
Alienosporites franconicus n.sp. (see page 85)
Diagnosis: Azonotrilete megaspores, rounded to subtriangular in outline, diameter 190-215 µm. Trilete rays 12-18 µm high, 10-16 µm wide, extending 0,6-0,7 of spore radius, vertex broad, rounded. Curvaturae absent.
Area ornamented with radially arranged low ridges, closely packed, 10-40 µm long, 2-4 µm wide, and oval verrucae. Near the apex the radial orientation of sculptural elements diminishes.
Spore surface outside the area foveolate with numerous deep, roundish foveolae, 2-4 µm in diameter. distance between foveolae 3-7 µm.
Remarks: Alienosporites cf. franconicus n.sp. (see page 85) is a bit smaller, the area is smooth.
Horstisporites selaginelloides n.sp. (see page 90-93)
Diagnosis: Azonotrilete megaspores, outline rounded to subtriangular, bastioned, diameter 190-450 µm. Trilete rays in most cases straight, rarely winding or closely folded, forming clearly delineated, moderately high ridges with rounded vertex, 15-37 µm high, 1122 µm wide, extending 0,55-0,85 of spore radius, lowering ± markedly towards the ends where they merge with the reticulate sculpture. Curvaturae absent.
Reticulate ornamentation highly variable. All transitions are present from spores covered all over with a perfect reticulum also reaching up to the vertex of trilete rays, to spores with far-reaching reduction of the reticulum, ornamented only with single or rarely joint rugulae. In general the reticulum is developed best on the distal hemisphere and gets more and more reduced towards the proximal pole.
The most common type of ornamentation is a perfect to slightly reduced distal and equatorial reticulum that changes gradually into single or sparsely anastomosing ridges and irregular verrucae on the area, especially near the apex and on the flanks of trilete rays.
The shape of muri varies from walls, 7-12 µm wide, 8-22 µm high (relatively constant within single specimen), with broad, rounded crests, to delicate ridges, membraneous at the top, varying in hight between 6 µm and 24 µm. Intersections of muri often elevated. Lumina roundish to polygonal in outline, depending on the shape of muri, diameter 6-70 µm.
Diameter of spore wall 8-13 µm. Exoexine granulose with membraneous, dense covering <1 µm. Intexine membraneous, frequently forming a shrunken mesospore, attached to the exoexine only in the apical region.
Erlansonisporites fimbriatus n.sp. (see page 93-94)
Diagnosis: Azonotrilete megaspores, outline rounded, bastioned, diameter 314-470 µm. Trilete rays straight to slightly bent membraneous bands, evenly high 30-40 µm, 4-6 µm wide, extending 0,8-0,9 of spore radius, merged with sculpture at the ends. Top of trilete rays widened up to 15 µm by ragged appendages, attached horizontal or obtuse on both sides of the vertex. Appendages with several slender, pointed and hooked processes.
All over the spore surface, the sculpture consists of membraneous muri similar to the trilete rays, up to 40 µm high, with crests widened by ragged appendages. Muri form an imperfect reticulum in their basal parts. They are interrupted by single incisions reaching down to the base and are partially torn, don't reach maximum height and lack terminal appendages (?secondary effect). Lumina irregulary polygonal in outline, diameter 20-50 µm.
Thickness of spore wall 12-16 µm, exoexine spongiose, made up of a meshwork of sporopollenin threads. Intexine not discernible.
Hughesisporites tectus n.sp. (see page 97)
Diagnosis: Megaspores, rounded in outline, diameter 310-390 µm. Dehiscence not discernible, obscured by ornamentation, covering almost entirely the proximal hemisphere. Ornamentation consists of flat, flap-shaped appendages, 20-40 µm wide, 25-50 µm long, with rounded or ragged ends, and of winding baculae, oval in outline, 15-20 µm wide, 25-50 µm long, ends rounded or truncated, rarely pointed. As a state of preservation appendages are merged to form a homogenous, cauliflower-like structure. Curvaturae absent. Distal hemisphere without ornamentation, smooth, slightly lustrous. Thickness of spore wall 10-15 µm, exoexine spongiose, intexine membraneous.
Tenellisporites verrucosus n.sp. (see page103-104)
Diagnosis: Coronate megaspores, rounded to subtriangular in outline, diameter (without corona) 435-750 µm. Trilete rays reaching the equator, up to 160 µm high, 15-25 µm wide. They consist of band-shaped elements ± grown together, free endings rounded. Variations in length, width and extent of fusion between the elements give the trilete rays an irregular, cockscomb-like appearance.
The trilete rays pass over into the equatorial corona, 100-150 µm (max. 290 µm) wide, consisting of straight to slightly bent, band-shaped appendages, 20-40 µm wide, partly joint at the base.
Area with low to hemispherical verrucae, circular to oval in outline, diameter 35-50 µm. Verrucae sometimes joint at the base to form radially arranged, winding ridges. Larger, baculae- or capilli-shaped appendages are rare on the proximal hemisphere.
Distal hemisphere with long, band-shaped appendages, oval in outline, diameter 20-40 µm, length up to 200 µm. Space between appendages 40-100 µm, ornamented with low verrucae. Long appendages in some specimens reduced to coni and blunt baculae.
Thickness of spore wall 38-45 µm. Exoexine separable in two layers. Outer exoexine 9-12 µm thick, granulose, made up of closely packed sporopollenin grains with sparse labyrinthic interspaces < 0,5 µm. Inner exoexine 28-33 µm thick, spongiose meshwork of sporopollenin threads. Intexine membraneous, thickness < 1 µm.
Aneuletes karnicus n.sp. (see page 105)
Diagnosis: Megaspores, rounded in outline, without discernible trilete mark or clearly delineated area, diameter 334-422 µm. Irregular, low verrucae with diameters up to 30 µm and winding, knobby ridges are developed in an area extending half the diameter of spores. Sculptural elements about 20 µm high, spaced 10-20 µm. Spore surface between this appendages finely granulate, smooth outside the ornamented field.
Sexaneuletes nudus n.sp. (see page 108-109)
Diagnosis: Megaspores, rounded in outline, diameter 360-485 µm, bearing a hexagonal mark, built up by ridges 20-22 µm high, 1215 µm wide. The mark consists of a hexagonal ring-structure which encloses a field measuring 0, 25-0,35 of spore diameter, and radial ridges, directed from the corners of the hexagonal mark towards the equator.
Roundish grana, measuring a few µm are restricted to the area enclosed by the hexagonal ring and the fields between the radial ridges. Spore surface smooth outside the hexagonal mark. Thickness of spore wall 12-16 µm.
The following new megaspore types are described in open nomenclature due lack of sufficient material for the erection of new species:
– Verrutriletes sp. (see page 75-76)
– Bacutriletes sp. (see page 82)
– Aneuletes sp. 1 (see page 106)
– Aneuletes sp. 3 (see page 107)
– Aneuletes sp. 5 (see page 107)
– Echitriletes sp. (see page 79)
– Radosporites sp. (see page 84-85)
– Aneuletes sp. 2 (see page 106-107)
– Aneuletes sp. 4 (see page 107)
Formal recombinations:
– Maexisporites robustus (FUGLEWICZ 1980) comb. nov.
Basionym: Trileites robustus, FUGLEWICZ 1980b, p. 234, pl. 23, fig. 1a-b
– Echitriletes digitiformis (FUGLEWICZ 1980) comb. nov.
Basionym: Narkisporites digitiformis, FUGLEWICZ 1980b, p. 235-236, pl. 23, fig. 3-5
– Hughesisporites triassicus (BANERJI, KUMARAN & MAHESHWARI 1978) comb. nov.
Basionym: Erlansonisporites triassicus BANERJI, KUMARAN & MAHESHWARI 1978, p. 11, pl. 6, fig. 42-47, text fig. 9
– Sexaneuletes acrochordones (FUGLEWICZ 1977) comb. nov.
Basionym: Aneuletes acrochordones, FUGLEWICZ 1977a, p. 424, pl. 40, fig. 5a-b
– Polaneuletes pomeranus (FUGLEWICZ 1977) comb. nov.
Basionym: Aneuletes pomeranus, FUGLEWICZ 1977a, p. 425, pl. 41, fig. 2, 5
Emendation: Tenellisporites marcinkiewiczae REINHARDT & FRICKE 1969, emend. (see page 100-103)
Emend. diagnosis: Coronate megaspores, rounded, rarely subtriangular in outline, diameter 340-580 µm. Trilete rays straight to slightly bent, 10-20 µm wide, up to 70 µm high (without appendages), reaching the equator. Crest of trilete rays ornamented with capilli, similar in shape to those forming the corona but shorter.
Equatorial corona consists of band-shaped, fragile capilli, up to 225 µm long, 20-40 µm wide, 10-25 µm thick, mostly free-standing, in places joint at the base. Capilli narrowing at the point of attachment, forming a groove.
Ornamentation highly variable, better developed on the distal hemisphere. Distally the sculpture ranges from blunt baculae, 1020 µm high, diameter 10-20 µm to pointed spinae and truncated baculae and capilli with a preserved length of 80 µm (primary length probably > 100 µm), diameter 10-20 µm. Space between appendages 20-40 µm, up to 60 µm in weakly ornamented specimens.
Proximal hemisphere ornamented with single coni or spinae, basal diameter 10-20 µm, length up to 40 µm. Rarely also band-shaped capilli up to 70 µm long occur. In several specimens the proximal sculpture is reduced to small grana or completely absent. Thickness of spore wall 14-20 µm.
In Tenellisporites marcinkiewiczae a small form occurs, distinguished by size (diameter 220- 350µm) and state of preservation. Small specimens subtriangular to triangular in outline, not completely flattened but proximal hemisphere raised, with trilete rays forming the edges of a three-sided pyramid. Distal hemisphere semiglobular, flattened or concave.
Remarks: Tenellisporites ornatus MARCINKIEWICZ 1992 falls within the range of Tenellisporites marcinkiewiczae REINHARDT & FRICKE 1969, emend., and is treated as synonym.
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