The exine ultrastructure of pollen grains in Gnetum (Gnetaceae) from China and its bearing on the relationship with the ANITA Group

Pollen grains of six species of Gnetum , G. parvifolium , G. hainanense , G. luofuense , G. pendulum , G. cleistostachyum and G. montanum , collected from China were examined using light, scanning and transmission electron microscopy. Pollen grains of Gnetum are subspheroidal or irregular-apolar, inaperturate, 11.21–22.44 µm in long axis and 9.34–20.47 µm in short axis. The exine surface is covered with spinules, 0.50(0.30–0.71) µm long spaced on average 1.12(0.81–1.46) µm apart. The exine is about 0.55 µm thick and comprises ectexine and endexine. The ectexine includes a thin tectum and an infratectal granular layer. The tectum protrudes outwards, forming the spinules. The endexine is composed of discontinuous lamellae, with lacunae between lamellae. The pollen grains of Gnetum are compared with those of Ephedra and Welwitschia , and also those of the ANITA Group of angiosperms, including Amborellaceae, Nymphaeales, Illiciales, Trimeniaceae and Austrobaileyaceae. The exine ultrastructures of Gnetum , Ephedra and Welwitschia are quite similar, consisting of tectum, granular layer and lamellated endexine. The exine ultrastructure of Gnetum is also similar to that of Nymphaea colorata (Nymphaeaceae) in the transitional region between the proximal and distal poles, but differs from that of Amborellaceae, Illicium religiosum (Illiciaceae), Schisandra (Schisandraceae), Trimeniaceae and Austrobaileyaceae. This comparison of exine ultrastructure provides new evidence for consideration of the relationship between Gnetum and the ANITA Group.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 415–425.     

A phylogeny of the families of fossil and extant tetraodontiform fishes (Acanthomorpha, Tetraodontiformes), Upper Cretaceous to Recent

A data matrix is presented of 210 morphological characters (mostly osteological, some external) for 20 extant taxa of the ten Recent families of tetraodontiform fishes and 36 fossil tetraodontiforms. The oldest of these are from the Upper Cretaceous (95 Mya); most are from the Lower to Middle Eocene (50–58 Mya). There are two outgroup taxa (a zeiform and a caproid). A cladistic analysis of this matrix for only the extant taxa produced two equally parsimonious trees that call into question the monophyly of some of the previously accepted major higher-level tetraodontiform clades. Inclusion in the analysis of the large number of available fossil taxa helps to resolve relationships between family level clades. The new phylogenetic hypothesis, together with stratigraphic and biogeographical data, is used to discuss scenarios of the origin and evolution of the major clades of the order.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society , 2003, 139 , 565−617.     

A new genus of Mantispidae (Insecta: Neuroptera) from the Eocene of Germany, with a review of the fossil record and palaeobiogeography of the family

A new mantispid genus and species Symphrasites eocenicus gen. sp. nov. is described from the Middle Eocene of the Messel Pit fossil site, Germany. It has been placed, with confidence, in the subfamily Symphrasinae, the fossils of which were previously unknown. A review of the known fossil species of Mantispidae is provided, and their systematic placements are discussed. Liassochrysa stigmatica Ansorge & Schlüter, 1990 is assigned to Mantispidae, and therefore Liassochrysidae is a new synonym of Mantispidae; a second, more complete specimen of Mesomantispa sibirica Makarkin, 1997 is described from the Early Cretaceous Baissa locality, Russia; Mantispidiptera Grimaldi, 2000 is excluded from the family; Vectispa Lambkin, 1986 is referred to subfamily Mantispinae; and the assignment of Whalfera Engel, 2004 to Rhachiberothidae is validated. The origin and palaeobiogeography of the mantispids are briefly discussed: the concept of ousted relicts – which assumes that former widely distributed taxa were replaced with groups originating in the tropics – is assumed to best explain the present distribution of the family.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 149 , 701–716.     

A palynological study of the genus Mentha L. (Lamiaceae)

The pollen morphology and exine structure of 10 Mentha L . species were investigated using light microscopy and scanning electron microscopy. The pollen grains of all 11 species were hexazonocolpate with granular membranes and a circular amb, varying in shape from prolate-spheroidal to suboblate. Different colpus shapes were recognized in M . ×  dumetorum . The exine was bireticulate in section Pulegium , and reticulate in section Menthae . A correlation was found between pollen size and chromosome number. The results indicate that the pollen characters of the genus Mentha are valuable for taxonomic applications and may be useful for classification.  © 2008 Uludag University. Journal compilation © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 141–154.     

Erdtmanitheca portucalensis,a new pollen organ from the Early Cretaceous (Aptian–Albian) of Portugal with Eucommiidites-type pollen

A new lignitised, slightly compressed pollen organ, Erdtmanitheca portucalensis, with affinities to extinct Erdtmanithecales from the Early Cretaceous (Aptian–Albian) of Vale de Água (Lusitanian Basin, western Portugal), is described. The pollen organ is composed of loosely arranged microsporophylls radiating from a central core. The estimated number of microsporophylls is about 100–150. The microsporophylls are sessile and ellipsoidal to barrel-shaped with a flattened or slightly apically depression containing about ten narrow sporangia. The sporangia enclose abundant well-preserved pollen grains of Eucommiidites-type. Pollen grains found in situ are elliptical in equatorial outline, about 16.0–27.2 μm long and 11.9–16.4 μm wide. The main (distal) colpus is long with expanded rounded ends. It is flanked by two subsidiary colpi in an almost equatorial position. The surface of the pollen wall is psilate and occasionally punctate. The ektexine is composed of a distinct tectum, granular infratectal layer and a thin foot layer. The endexine is thick and laminar. The new Early Cretaceous Portuguese pollen-organ is similar in several respects to that of Erdtmanitheca texensis described from the Late Cretaceous of Texas, USA. The new fossil species further documents the importance of the Bennettitales-Erdtmanithecales-Gnetales group in the Early Cretaceous floras of Portugal extending the stratigraphic and geographical distribution of the genus with regard to systematic and phylogenetic significance of the Eucommiidites-producing plants that may have been co-occurring with the Early Cretaceous diversification of angiosperms. It is ascertained that perforate tectum occurs in pollen grains with a well-developed foot layer as well as in pollen grains in which a foot layer is poorly developed or lacking, and that pollen features do not support a separation of the Erdtmanithecales seeds and pollen organs.     

The ultrastructure of fossil dispersed monosulcate pollen from the Early Cretaceous of Transbaikalia,Russia

The general morphology, surface sculpturing, and exine ultrastructure have been studied in dispersed monosulcate pollen from the Early Cretaceous of Transbaikalia, Russia. The pollen grains dominate the palynological assemblage extracted from coal deposits of the Khilok Formation in the Buryat Republic, which also contain ginkgoalean leaves of Baierella averianovii as the only constituent of the assemblage of plant megafossils. The relationship between the pollen grains and ginkgoalean leaves from this autochthonous burial is hypothesised on the basis of taphonomical analysis and palaeobiogeographical data. It is shown that the ectexine of the pollen grains includes a thick solid tectum, a thin granular infratectum and a thin foot layer; the endexine is fine-grained, slightly more electron-dense than the ectexine, and is preserved only in places. The distal aperture is formed by a thinning of the exine. No analogous ultrastructure has been described so far in fossil pollen grains of this morphotype studied ultrastructurally from in situ material. For comparison, we also studied the exine ultrastructure of pollen grains Ginkgo biloba. The fossil pollen is not identical to pollen of extant G. biloba, but shows several significant similarities in the exine ultrastructure, which does not contradict the presumable ginkgoalean affinity of the fossil pollen.     

裸子植物雄球花——纤细堆囊穗的修订

研究了采自中国东北晚三叠世羊草沟组的一种裸子植物雄球花——纤细堆囊穗。通过对新材料的研究,发现这种雄球花小孢子叶末端的裂片在形态上差异很大,这是原来没有发现的十分重要的特征。这些保存精美的化石对于纤细堆囊穗特征的阐明和修订以及物种复原很有帮助。将中国的标本与西伯利亚堆囊穗、小堆囊穗、乌尔马堆囊穗和被定为长叶拜拉的雄球花进行了比较,发现它们与纤细堆囊穗在特征上一致,故将它们处理为纤细堆囊穗的异名。修订后的纤细堆囊穗包括上面所提到的所有种。同时,也讨论了堆囊穗属可能的演化意义。它可能是银杏属的远祖,经过小孢子囊数目的减少和小孢子叶长度的缩短而演化到现在的银杏,而产自辽西早白垩世的辽宁银杏可能代表了堆囊穗和现代银杏在形态演化上的一个中间步骤。     

A new late Westphalian fossil marattialean fern from Nova Scotia

Sydneia manleyi gen. et sp. nov. is based on part of a fertile frond from the upper Westphalian D of the Sydney Coalfield, Nova Scotia, Canada. It has small synangia composed of laterally fused sporangia that are elongate and with a circular cross-section. The sporangia yielded variably sized monolete and trilete spores with laevigate and microspinate ornamentation; intermediate forms were also observed. The spores can be correlated with the sporae dispersae species Latosporites minutus , Punctatosporites oculus and Laevigatosporites minimus . Size distribution of the spores is variable and highly skewed, suggesting heterogeneity of the spores within the sporangium. Spore ultrastructure indicates that the fossil is part of a fern, and the morphology of the spores and synangia indicate marattialean affinities.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 199–212.     

First record of fossil Mesozoic Ctenopoda (Crustacea, Cladocera)

Pre-Pleistocene representatives of the crustacean order Ctenopoda Sars, 1865 are unknown. Here we describe Mesozoic fossil specimens of ctenopods from two localities in Mongolia: Khotont (Jurassic/Cretaceous boundary, about 145 Mya) and Khutel Khara (Lower Cretaceous, about 129 Mya). All specimens apparently belonged to the tribe Latonini Korovchinsky, 1986 of the subfamily Sidinae Baird, 1850. At the Khotont site, ctenopods were the most numerous microscopic animal fossils. We assigned these cladocerans to a new genus and species Archelatona zherikhini gen. nov., sp. nov. Our findings support a pre-Cretaceous origin for cladocerans.  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 146 , 269–274.     

Reproductive ecology of the endemic Lecocarpus pinnatifidus (Asteraceae) in an isolated population in the Galápagos Islands

Lecocarpus pinnatifidus is an endemic member of the Asteraceae occurring on only one island in the Galápagos archipelago. The capitula are large with female ray florets and male disc florets. They are self-compatible but this study suggests fruit set is pollen limited. Visits from Xylocopa darwini and other larger insect pollinators are rare, and small insects seem to be the main pollinators. Small insects carry few pollen grains and most likely mediate self-pollinations. Self-compatibility and seed set after selfing are the most common reproductive strategy in the Galápagos Islands and L. pinnatifidus seemingly fits well into this group.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 171–180.     

A summary of fossil records for Arecaceae

Of all monocotyledons the Arecaceae displays by far the richest fossil record, and there is an extensive literature. The earliest unequivocal fossil palm material probably dates from the early to mid Late Cretaceous (Turonian > Coniacian > Santonian). The records are geographically widespread and comprise a wide range of organs: leaves, cuticles, stems, rhizomes, roots, fruits, seeds, endocarps, rachillae, peduncles, inflorescences, individual flowers and pollen. For some of these organs records are rare while for others, such as leaves, stems and pollen, records are abundant. However, fossil material often lacks sufficient diagnostic detail to allow reasonable association with living palm taxa beyond, or even to, subfamilial level. Nevertheless, many fossil genera and numerous species have been described. A brief survey of palm fossil records is presented, and their taxonomy and morphological limitations are considered. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 39–67.     

The age of major monocot groups inferred from 800+ rbcL sequences

Phylogenetic research on monocots has been extraordinarily active over the past years. With the familial interrelationships being sufficiently understood, the question of divergence times and crown node ages of major lineages comes into focus. In this study we present the first attempt to estimate crown and stem node ages for most orders and families of monocots, based on rbcL sequence data and comprehensive taxon sampling. From our analysis it is obvious that considerable monocot diversification took place during the Early Cretaceous, with most families already present at the Cretaceous–Tertiary boundary. Araceae, Arecaceae and Orchidaceae are among the oldest families with crown node ages reaching back into the Early Cretaceous. We comment on possible error sources and the necessity for methodological improvement in molecular dating.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 385–398.     

The cytological origin of the polyads and their significance in the reproductive biology of Mimosa bimucronata

The mechanism of polyad formation in Mimosa bimucronata (DC.) Kuntze is described and its significance in the reproductive biology is discussed. In this species c . 500 complexes of two coupled pollen mother cells (PMCs) per pollen sac are formed after the last mitotic division of the sporogenous tissue. All the pollen grains of each complex remain attached and form a bitetrad. This mechanism leads to the formation of many polyads per pollen sac. On this basis, we propose that in Mimosa the number of pollen grains per polyad (eight or 16) is determined by the number of cells that remain attached after the last mitotic divisions of the sporogenous tissue. Concerning the biological significance of the polyads in M. bimucronata , we find that the number of pollen grains per polyad is correlated with the number of ovules per ovary, and that the internal dimensions of the pit-shaped stigma are sufficient just for one polyad to be localized in it. Based on the number of polyads per flower this species has a high pollen/ovule ratio characteristic of xenogamous plants, in opposition to that expected for plants with composite pollen dispersal units. In contrast, it has low pollination efficiency, low fruit set, a 1/1 relationship between the pollen grains of a polyad and the number of ovules per ovary, and high seed set per fruit. These facts support the hypothesis that the occurrence of polyads in M. bimucronata would be an adaptation helping to ensure high seed set following a single cross pollination event.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 343–349.     

A preliminary palynological characterization of Spanish thyme honeys

Pollen was analysed in 25 thyme honey samples from Spain. The honey samples were provided by professional beekeepers, and pollen was obtained by centrifugation. A minimum of 8% of Thymus sp. pollen is considered sufficient to typify a honey as unifloral when considering pollen grains from anemophilous and nectarless plants. The quantitative analysis showed that nectar is the main honey source in the samples studied. The qualitative analysis of the samples revealed the presence of 53 taxa belonging to 27 families. The Spanish thyme honeys of the studied region are characterized by their medium to high numbers of grains of pollen (NGP; mean = 155 000) and their medium to high content of honeydew indicator elements (HDE; mean = 8300). Genista type (present in 100% of the samples), Echium plantagineum and Reseda luteola (90%), Eucalyptus type (80%), Calendula type and Olea europaea (75%), and Cistus monspeliensis (70%) may be mentioned among the characteristic accompanying species of this honey type.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 323–330.     

Pollen structure, tetrad cohesion and pollen-connecting threads in Pseuduvaria (Annonaceae)

The structure of the pollen of 42 species of Pseuduvaria (Annonaceae) is described. The pollen is consistently inaperturate, isopolar and radially symmetrical. Four basic patterns of exine sculpturing are identified: rugulate, verrucate, scabrate and psilate. The exine stratification of one representative species, P. macrocarpa , is shown to be entirely ectexinal. The ectexine consists of a discontinuous outer tectal layer, a columellar infratectal layer, and an inner lamellar foliated foot layer; the intine is very thin and fibrillar. The pollen is invariably released as acalymmate tetrads, in which the tectum is absent from the proximal walls. The individual pollen grains within the tetrads are connected by crosswall cohesion, involving both exine and intine; this form of cohesion has not hitherto been reported in the Annonaceae. In addition, pollen grains of neighbouring tetrads are connected in two different ways, viz. short exine connections and non-sporopollenin pollen-connecting threads. Neither of these cohesion mechanisms has previously been reported for the genus. The function of the various forms of cohesion between pollen grains and tetrads in Pseuduvaria is discussed as a mechanism to enhance the efficiency of pollination by enabling the fertilization of multiple ovules following a single pollinator visit.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 69−78.     

A new choristodere (Reptilia: Diapsida) from the Lower Cretaceous of western Liaoning Province, China, and phylogenetic relationships of Monjurosuchidae

The publication of the scientific name Monjurosuchus splendens in 1940 documented the first tetrapod fossil of the later world-renowned Jehol Biota. For more than half a century since this discovery, however, Monjurosuchus has remained as a monotypic genus of the family Monjurosuchidae, and the relationships of the family with choristoderes have not been correctly recognized until quite recently. In this paper, a new monjurosuchid is named and described based on a nearly complete skull and postcranial skeleton from the Early Cretaceous Chiufotang Formation exposed near Chaoyang, western Liaoning Province, China. This new material documents the first occurrence of monjurosuchid choristoderes outside the type Lingyuan area, and extends the geological range of the family from the Yixian Formation to the younger Chiufotang Formation. Cladistic analyses were conducted with inclusion of monjurosuchids, and the results support the placement of the family Monjurosuchidae as a primitive clade outside the Neochoristodera. A new classification scheme is proposed for choristoderes on the basis of the recovered phylogenetic framework of the group.  © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society , 2005, 145 , 427–444.     

Morphology and phylogenetic relationships of a new eschrichtiid genus (Cetacea: Mysticeti) from the Early Pliocene of northern Italy

A new eschrichtiid, Eschrichtioides gastaldii gen. nov., comb. nov. , is established based on a specimen previously assigned to Balaenoptera gastaldii Portis, 1885. The holotype is from the Early Pliocene of north-east Italy. It represents a fossil mysticete closely related to the living grey whale, Eschrichtius robustus . Comparative morphology and phylogenetic analysis support the monophyly of Eschrichtiidae and Cetotherium -like mysticetes and a sister group relationship between this clade and Balaenopteridae. Eschrichtiid fossils previously described are all from the Pleistocene and Late Pliocene while Eschrichtioides gastaldii is from the Early Pliocene. The recognition of this new eschrichtiid genus suggests that the Mediterranean trophic web of the Early Pliocene was more complex than at present and that the Neogene mysticete family-level biodiversity of the Mediterranean was higher than that currently observed in this basin.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 153 , 161–186.     

Ontogeny of a new Palaeogene pipid frog from southern South America and xenopodinomorph evolution

Lacustrine interbeds of a volcaniclastic succession that crops out extensively in north-western Patagonia yielded impressions of articulated, nearly complete, frogs of different ontogenetic stages including tadpoles. The stratigraphic position of the fossil bearing beds in this sequence and evaluation of palaeofloristic data against the record of climatic change in southern high latitudes support a middle Eocene – early Oligocene age for the frogs. These frogs are described as a new genus and species that resembles the late Palaeocene ' Xenopus' romeri from Brazil, and differs from the middle Eocene S. pascuali from Patagonia, in the relatively wide and short braincase and fused first two presacral vertebrae. However, unlike ' X. '  romeri , the nasals are paired and bear short, but distinct, rostral processes. A parsimony analysis based on 49 adult osteological characters demonstrates that these South American fossil pipids are closely related to xenopodines, restricted to the African continent today, although their interrelationships remain poorly resolved. Interpretation of the ontogenetic stages exemplified by the fossil specimens suggests a developmental pattern more similar to that of extant xenopodines than to the ontogeny of more distant pipoid relatives. Moreover, the similarity between these fossil larvae and those of Xenopus and Silurana strongly suggests similar habits. Many of these larval features may be considered as caenogenetic, i.e. specializations of the tadpoles as obligate, microphagous suspension feeders.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society , 2003, 139 , 439-476.     

Water lilies and scarabs: faithful partners for 100 million years?

Night-flowering water lilies (Nymphaeaceae) in South America are pollinated by Cyclocephala scarab beetles (Scarabaeidae: Cyclocephalini) in a specialized relationship involving synchronized flowering movements, strong floral scent, food tissues, and heat-producing flowers. We report that a similar and closely related association exists in West Africa between Nymphaea lotus L. and Ruteloryctes morio Fabricius (Cyclocephalini). This finding strongly supports a late Early Cretaceous origin of a symbiosis between the night-flowering water lilies and pollinating Cyclocephalini beetles. We believe that this is the first unambiguous evidence of a plant-pollinator relationship of this age.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 539–543.     

The family Alestidae (Ostariophysi, Characiformes): a phylogenetic analysis of a trans-Atlantic clade

The overall most parsimonious hypothesis of relationships based on 200 characters indicates that the Alestidae is the closest relative of Chalceus , a genus previously assigned to the Neotropical Characidae. Chalceus is shifted into the Alestidae, which becomes the only trans-Atlantic family level group within the Characiformes. Various previously proposed suprageneric assemblages within the Alestidae (e.g. Petersiini) failed to delimit monophyletic groups under the intrafamilial phylogenetic analysis. The evaluation of fossil alestids within the context of the phylogeny indicates that the ancestors of Alestes , Arnoldichthys , Brycinus , Bryconaethiops and Hydrocynus evolved prior to the early Eocene (Cuisian of Upper Ypresian), 49–54.8 million years ago, with the fossil Alestoides most closely related to Alestes. The phylogenetic information further indicates a minimum age of 90–112 million years for the Alestidae. Contrary to previous hypotheses, the fossil African Sindacharax was found to be most similar to the clade including the alestid genus Bryconaethiops rather than most closely related to the South American subfamily Serrasalminae. Evaluation of the fossil Mahengecharax carrolli fails to support its hypothesized placement as the sister group to all Recent members of the Alestidae. Two separate episodes of miniaturization and one episode of gigantism occurred within the evolution of the Alestidae.  © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society , 2005, 145 , 1−144. No claim to original US government works.