Comparative ultrastructure of the megaspores of the triassic lycopsid Pleuromeia rossica Neuburg

Lugardon, Bernard; Grauvogel‐Stamm, Léa; Dobruskina, I. A.

doi:10.1016/s1251-8050(00)00145-2

Cited by 14 publications

(16 citation statements)

References 2 publications

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“…Numerous fossil megaspores assigned to lycopsids present similarities in their ultrastructure with the Isoetales (Wellman 2002). this is the case of L. magnus in which a spongy exospore coincident with the general scheme described by Lugardon et al (2000) for extant lycopsids was observed. In addition, it was recognized a structural setup of sporoderm elements similar to those described in extant species of Isoetes L, which present a threedimensional network of fused rodlets forming heterogeneous spaces (Macluf et al 2003).…”

Section: Comparisons and Lycopsid Botanical Affinitymentioning

confidence: 70%

Morphology of the megaspore Lagenoisporites magnus (Chi and Hills 1976) Candilier et al. (1982), from the Carboniferous (lower Mississippian: mid-upper Tournaisian) of Bolivia

Quetglas

Macluf

Pasquo

2019

An. Acad. Bras. Ciênc.

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the morphology and structure of megaspores assigned to Lagenoisporites magnus from the toregua Formation, retama Group, mid-upper tournaisian of Bolivia were studied. the analysis was performed with light, fluorescence and scanning electron microscopy. Megaspores were laterally compressed and presented a spherical body with a proximal gula, of the hologula type. Gula had verrucae ornamentation and the spore body presented complex processes consisting of a bulbous base and an internally partitioned projection with sharp apex. In addition to this main ornamentation, perforations were present throughout the spore surface. Megaspores showed well marked curvaturae perfectae due to the abrupt transition existing between the gula ornamentation and the spore body processes. these megaspores were assigned to heterosporous arborescent lycopsids of the Lepidocarpaceae family, as in section view, exospore structure presented a three-dimensional network of fused elements. Likewise, due to a similarity found between sporoderm and Isoetes L. structure, it is evident that megaspores structure has remained intact inside the heterosporous lycopsids. therefore; the L. magnus structure not only would confirm its affinity with the Lycophyta fossils but also with the living ones.

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Section: Comparisons and Lycopsid Botanical Affinitymentioning

confidence: 70%

Morphology of the megaspore Lagenoisporites magnus (Chi and Hills 1976) Candilier et al. (1982), from the Carboniferous (lower Mississippian: mid-upper Tournaisian) of Bolivia

Quetglas

Macluf

Pasquo

2019

An. Acad. Bras. Ciênc.

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“…Likewise, Kovach (1994) suggests that there is an ultrastructural affinity between mesozoic megaspores and present Lycophyta megaspores, which would also indicate a probable conservation of the sporoderm structure. Lugardon et al (1999Lugardon et al ( , 2000 and Grauvogel-stamm and Lugardon (2004) compared megaspores and microspores of living species of Isoetes with spores of the Triassic period, assigned to Isoetes, and came to similar conclusions in the sense that there is a similarity in the ultrastructure and organization of the fossil and living spores. The perispore (P) and the para-exospore (Pex) take part in the formation of the supra-laesural expansion.…”

Section: Discussionmentioning

confidence: 90%

Morphology and ultrastructure of megaspores and microspores of Isoetes sehnemii Fuchs (Lycophyta)

Macluf

Morbelli

Giudice

2010

An. Acad. Bras. Ciênc.

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The morphology and wall ultrastructure of megaspores and microspores of Isoetes sehnemii that grows in Brazil were analyzed as part of the study of the Isoetaceae present in Southern South America. The observations were performed with light, scanning and transmission electron microscopes. The megaspores are trilete, 350-450μm in equatorial diameter. The surface is reticulate. In section, the sporoderm is 100μm thick including the ornamentation. The wall is composed of a siliceous perispore, which consists of short fused flatten, elements forming a three-dimensional mesh. The exospore has two zones of different structure. The endospore is fibrillar. The microspores are monolete, 21-27μm in equatorial diameter. The sporoderm is composed of a sporopollinic rugulate perispore. A space between the paraexospore and the exospore is evident. The exospore is compact. The endospore is fibrillar. The ultrastructural analysis makes homologies evident concerning structure and organization of the layers below the perispore in both spore types. A possible similarity and stability in the ultrustructure of the present spores and fossils could be also inferred. In addition, there would be a correlation among the plant habitat, the spore ornamentation and the geographic distribution.

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“…However, the specimens are markedly smaller (one-half to two-thirds the diameter) than otherwise similar Early Cretaceous forms from Argentina assigned to Trileites spp. by Baldoni and Batten (1997 Marcinkiewicz, 1971 are also similar to these Inverleigh megaspores (Batten, 1988;Koppelhus & Batten, 1989;Marcinkiewicz, 1992;Lugardon et al, 2000;Batten et al, 2010;Lupia, 2011), but subtle differences in the robustness, sinuosity and extent of the laesurae, together with their great temporal and geographic separation suggest that they represent distinct species.Description. -Strongly compressed and folded megaspores ( Figure 6A, B, K, L) suggesting a thin wall; distal side hemispherical ( Figure 6H), proximal hemisphere forming a low pyramid ( Figure 6C); amb convexly subtriangular to subcircular.…”

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confidence: 87%

Megaspore and microfossil assemblages reveal diverse herbaceous lycophytes in the Australian Early Jurassic flora

McLoughlin

Jansson

Vajda

2014

Grana

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Here, we describe and illustrate by transmitted light and scanning electron microscopy the first Australian Jurassic megaspore assemblages. The megaspores and other mesofossils were isolated from terrestrial deposits of the Marburg Subgroup (late Pliensbachian) at Inverleigh Quarry, Clarence-Moreton Basin, eastern Australia. Nine megaspore taxa are identified including one new species: Paxillitriletes rainei. Miospore assemblages recovered from the same samples at Inverleigh reveal a slightly higher diversity of lycophyte microspores. The collective megaspore suite from Inverleigh shares several genera with mid-Mesozoic assemblages from widely distributed parts of the world, but most of the Inverleigh species have subtle morphological differences from congeneric forms elsewhere. The megaspores accumulated in fluvial floodplain facies and are associated with mostly dissociated isoetalean leaf debris. Other mesofossils in the sampled interval include annelid egg cases, dispersed seeds and charcoal. Invertebrate burrows and possible vertebrate tracks also occur in this succession. Lycophyte macrofossils are otherwise known from only two other Australian Jurassic deposits. The richness of the megaspore and microspore suites attest to a significant diversity of lycophytes in the Australian Jurassic floras not hitherto appreciated from described macrofloras.Keywords: lycophyte megaspores, Isoetales, mesofossils, microspores, Pliensbachian, Clarence-Moreton Basin, GondwanaThe Hettangian-basal Toarcian interval is bracketed by two globally recognised mass extinction events. In the Gondwanan terrestrial realm, the RhaetianHettangian transition is marked by the collapse of the Dicroidium/Falcisporites flora that had dominated most of the Triassic (Anderson et al., 1999). In its place arose a flora rich in Bennettitales, Caytoniales and cheirolepidiacean conifers (Gould, 1975;Hill et al., 1999). A further transition in the Toarcian saw a decline in cheirolepids and increases in araucariacean and podocarpacean conifers and pentoxylalean gymnosperms in Australia (Turner et al., 2009). The Australian Hettangian-Toarcian floras remain poorly understood, being represented by only a few macrofloral assemblages from central eastern Australia that have yet to be fully described (Jones & de Jersey, 1947;Gould, 1968Gould, , 1974Gould, , 1975Pattemore, 2000;Pattemore & Rigby, 2005;Jansson et al., 2008b). Palynofloras provide a broader picture of Australia's Early Jurassic floristic succession (Evans, 1966;de Jersey, 1975;Filatoff, 1975;Burger, 1976Burger, , 1994Helby et al., 1987;Turner et al., 2009), but the biological affinities of some palynomorphs remain poorly resolved (Balme, 1995) and spore-pollen assemblages may be subject to significant taphonomic sorting (Holmes, 1994). Mesofossils (0.2-5.0 mm remains including megaspores, sporangia, seeds and charcoalfied plant fragments) represent an additional avenue for evaluating fossil plant diversity. However, mesofossil suites have been largely neglected in past palaeobotani...

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Comparative ultrastructure of the megaspores of the triassic lycopsid Pleuromeia rossica Neuburg

Cited by 14 publications

References 2 publications

Morphology of the megaspore Lagenoisporites magnus (Chi and Hills 1976) Candilier et al. (1982), from the Carboniferous (lower Mississippian: mid-upper Tournaisian) of Bolivia

Morphology of the megaspore Lagenoisporites magnus (Chi and Hills 1976) Candilier et al. (1982), from the Carboniferous (lower Mississippian: mid-upper Tournaisian) of Bolivia

Morphology and ultrastructure of megaspores and microspores of Isoetes sehnemii Fuchs (Lycophyta)

Megaspore and microfossil assemblages reveal diverse herbaceous lycophytes in the Australian Early Jurassic flora

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