Plant assemblages from the Silurian of southern Bolivia and their palaeogeographic significance

Abundant but fragmentary plant fossils are described from two locations in shallow water marine facies of the Lipeón (previously Kirusilla) Formation of southern Bolivia. Field relationships and limited palaeontological data suggest that the rocks are of Ludlow to possibly early P'ídolí age (i.e. late Silurian). The majority of the fossils are sterile coalified compressions or impressions of parallel-sided axes, some with branching typical of Hostinella . No tracheids have been found and such remains are best described as rhyniophytoid. Fragments with irregular branching and variable axial diameters probably belong to algae with some similarities to Hungerfordia and Buthotrephis . Rarely axes terminate in clearly delimited globular or elliptical swellings that are interpreted as sporangia, although no spores have been recorded. The most completely preserved specimens have dichotomous branching ending in predominantly elliptical sporangia with distal borders and closely resemble Cooksonia ca-ledonica . Solitary isolated sporangia are vertically elliptical (cf. Tarrantia ), globose (cf. C. cambrensis, C. hemi-sphaerica ) or laterally extended (cf. C. pertoni ). Those with cup- or funnel-shaped morphologies superficially resemble the rhyniophytoid Steganotheca or dyad-containing Culullitheca . Thus while it is impossible to compare with confidence the taxonomic composition of Bolivian assemblages with coeval ones, their overall morphological grade is closer to material collected from circum-northern Atlantic localities than from assemblages in Australia and Kazakhsta/nChina. Palaeogeographically this translates into floristic similarities between Gondwanan high latitudes and equatorial Laurussia rather than with low latitude, north-eastern Gondwana or with a low latitude Kazakhstan/ Xinjiang micro-palaeocontinent     

REINTERPRETATION OF THE SILURIAN SCORPION PROSCORPIUS OSBORNI (WHITFIELD): INTEGRATING DATA FROM PALAEOZOIC AND RECENT SCORPIONS

Abstract:  The morphology of the Late Silurian (Přídolí) scorpion Proscorpius osborni ( Whitfield, 1885 a ) (Arachnida: Scorpiones), from the Phelps Member of the Fiddlers Green Formation of New York, the 'Bertie Waterlime' of earlier stratigraphic schemes, is revised based on studies of new and existing material (a total of 32 specimens). Previous reports of four cheliceral articles, gnathobasic coxae, a labium and gill slits in P. osborni can be dismissed. However, we confirm the presence of both median and compound lateral eyes, a pair of tarsal claws, albeit on a more digitigrade foot compared to that of modern scorpions, more than five ventral mesosomal sclerites and a fairly modern pattern of metasomal (i.e. tail) carinae. The co-occurring Archaeophonus eurypteroides Kjellesvig-Waering, 1966 and Stoermeroscorpio delicatus Kjellesvig-Waering, 1986 are regarded as junior synonyms of P. osborni . Fossil scorpion higher systematics is plagued by a plethora of unnecessary and largely monotypic higher taxa and we draw on the results of Jeram's cladistic analysis from 1998 to synonymize formally a series of families and superfamilies with Proscorpiidae Scudder, 1885 .     

New chromosome counts in the Centaurea Jacea group (Asteraceae, Cardueae) and some related taxa

Twenty-seven chromosome counts are reported in 23 species of the genus Centaurea , mostly eastern endemic species of the Jacea group, which has become the core of the re-defined genus Centaurea . Twenty reports are new, one is a correction of a previous count, one is a confirmation of limited previous data and one represents a new basic number in the Centaureinae. The prevalence of the basic chromosome number x  = 9 among the Eastern sections of the Jacea group is confirmed, together with the close correlation between karyological data and classification of the genus. Two alternative hypotheses on the aberrant chromosome number (for the Centaureinae) found in C. behen are proposed. One of them, if verified, would confirm that a cycle of polyploidy and descending dysploidy is a key mechanism in the speciation of the group.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 145 , 345–352.     

ENIGMATIC WORM-LIKE ORGANISMS FROM THE UPPER DEVONIAN OF NEW YORK: AN APPARENT EXAMPLE OF EDIACARAN-LIKE PRESERVATION

Abstract:  The supposed polychaete annelid Protonympha salicifolia , from the Upper Devonian (Frasnian) of New York State, USA, is redescribed. P .  salicifolia has a bilateral and segmented body, but appears to have a 'mattress-like' construction with blade-like extensions along the margins. The affinities of P. salicifolia remain unresolved, but a proposed relationship to the annelids is unlikely. The preservation of the three known fossils, as mouldic imprints in sandstones, is strongly reminiscent of the circumstances associated with Ediacaran fossilization, and as such is an anomalous occurrence of such soft-part preservation in Phanerozoic sediments. Material associated with these enigmatic fossils has been referred to Palaeochaeta devonica , and also compared with the annelids. Such an assignment is also rejected. These fossils appear to be arthropodan, and are possibly myriapods. A supposed example of Protonympha (' P '.  marcellensis ) from the Middle Devonian of New York State is now excluded from this genus, and it may be a crustacean.     

Fruits and seeds of Ruppia (Potamogetonaceae) from the Pliocene of Yushe Basin, Shanxi, northern China and their ecological implications

Numerous fruits and seeds of Ruppia are reported from the Upper Pliocene (2.3–3.5 Myr ago) Zhangcun Formation in Yushe Basin, Shanxi, northern China. They are the first fossil Ruppia from China and demonstrate the importance of fruit and seed fossils in recording genera not represented by fossil leaves. These Ruppia are characterized by possessing a small oval endocarp, smooth endocarp surface, distinct elliptical external depressions, distinct apical mucro, slightly curved seed shape and conspicuous globose hilum. A new species, R. yushensis Zhao, Collinson and Li, is described from these endocarp and seed features. Comparison with the two European Miocene species, R. palaeomaritima Negru and R. maritime-miocenica Szafer, indicates the existence at that time of three different geographical and stratigraphical species. R. yushensis constitutes the first Pliocene record of Ruppia and extends the range of fossils of this genus from Europe to eastern Asia. R. yushensis is the only aquatic plant in the uppermost middle part of the Zhangcun Formation. This monotypic occurrence indicates a brackish, clear, tranquil and shallow lake in this region in the Late Pliocene. The smooth endocarp surface further suggests a warm temperate or temperate palaeoclimate.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 145 , 317–329.     

Shell colour polymorphism in the chiton Ischnochiton striolatus (Gray, 1828) (Mollusca: Polyplacophora) and habitat heterogeneity

Shell colour polymorphism was examined in a population of the polyplacophoran Ischnochiton striolatus (Gray, 1828) living on intertidal rocks in Búzios, Rio de Janeiro State, Brazil. Nine shell colours were identified: green (most common), grey, pink, cream, brown, orange, white, black and purple. The species habitat was also examined using three rock characteristics: volume; turnover frequency, caused by hydrodynamic disturbance; and chromatic composition. Chitons were most frequently encountered on the undersides of rocks of intermediate volume which experienced medium-intensity hydrodynamic disturbance, and which harboured a chromatically rich biotic community. These findings were in agreement with the Intermediate Disturbance Hypothesis. As chitons depend on the biotic community on rocks for food and shelter, a greater variety of colours could increase the chances of camouflage of the morphs against the background, favouring crypsis. It is likely that the frequency at which intermediate-volume rocks are overturned − thus exposing the chitons on them to light − would be sufficient for visual predators to act as selective agents.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 543–548.     

A new species of Ceratozamia (Zamiaceae, Cycadales) from Veracruz, Mexico

Ceratozamia huastecorum sp. nov. is from an isolated meseta or tepui-like mountain in the Huasteca region of northern Veracruz State, Mexico. It has affinity to C. morettii Vázq.Torres & Vovides from the Mexican transvolcanic mountain range, which lies over 200 km to the south. The most notable differences are in female cone colour, leaf and leaflet morphology and length. The specific epithet is chosen in honour of the Huasteca ethnic region of great cultural importance to northern Veracruz.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 141 , 395–398.     

New species and new records of Menegazzia (Parmeliaceae, lichenized ascomycetes) from Malaysia and Indonesia

The genus Menegazzia (Parmeliaceae, lichenized ascomycetes) in Malaysia and Indonesia is studied. Some specimens from Papua New Guinea are also included. The great majority of available specimens are from Kinabalu Park, State of Sabah, Malaysia. Three species are described as new to science, namely the two sorediate species M. capitata (from Sabah and Pahang in Malaysia) and M. sabahensis (from Sabah), and the fertile, primary species M. monospora (from Sabah and Papua New Guinea). M. asahinae , M. dissoluta , and M. efflorescens are reported for the first time from Malaysia, and M. subsimilis is reported for the first time from Malaysia and Indonesia. The subgenus Megamenegazzia is newly described to accommodate the large, broad-lobed species with numerous perforations on the lower surface. M. efflorescens is selected as the type species for the new subgenus. Notes are also provided on the type specimens of Hypogymnia pectinatula , a species originally considered as belonging to Menegazzia .  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 489–499.     

A new species of Achetaria (Plantaginaceae) from south-eastern Brazil

A new species, Achetaria latifolia V.C.Souza, is described and illustrated. It is characterized by its broadly ovate leaves, indument of stems and leaves of noncapitate hairs, and pubescent capsule. Achetaria latifolia is known only in the coastal dune-area of Cabo Frio region, Rio de Janeiro State, Brazil.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 73–75.     

Bauhinia larsenii, a fossil legume from Guangxi, China

Fossil leaves and a branch with a leaf and a pod attached have been discovered from Ningming County, Guangxi Autonomous Region, China, and are described as Bauhinia larsenii sp. nov. (Leguminosae: Cercideae). The strata from which the Bauhinia fossils were collected, namely the Ningming Formation, were dated as Late Eocene–Oligocene based on a combination of pollen, fauna and flora. The affinity of the new species to Bauhinia section Micralvesia subsection Viridescentes species is also discussed.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 437–440.     

Three new species of Echinops (Compositae, Cynareae) from Iran

As a result of extensive collections and subsequent determinations made in recent years through most regions of Iran (now preserved in herbarium TARI), three new species of Echinops ( E. longipenicillatus, E. procerus and E. shahrudensis ) are described and illustrated. All belong to E . sect. Oligolepis Bunge, which is endemic to Iran.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 181–186.     

A new species of Baragwanathia from the Sextant Formation (Emsian) Northern Ontario, Canada

Baragwanathia abitibiensis is described from the Sextant Formation of northern Ontario, Canada (middle to upper Kmsian age). The plant remains are primarily compressions in which flattened xylem strands, epidermis with stomata, and cuticle are well preserved. Pyrite permineralization of the leaves was Ibiuid in one specimen. Comparison with B. longijolia Lang & Cookson indicates remarkable morphological similarities and probable anatomical similarities although details of the structure of the epidermis and cuticle are lacking in B. longijolia. No information is available on the outline of the cauline xylem strand in B. abitibiensis nor on the form and position of the sporangia it bore. Comparisons are also made to species of Drepanophycus. The age of/?, longijolia and the Baragwanathia Flora, is discussed with particular reference to the putative dating of some specimens as Silurian. The morphological and anatomical complexity of Baragwanathia is at a level of advancement typical of Early to Middle Devonian lycopods. There is no evidence of precursors to the genus associated with the fragments of land vascular plants in the well-dated Silurian sediments of Wales, Czechoslovakia, New York State, or Podolia.     

Some remarks on the genus Astragalus sect. Incani in Iran

New findings are given for the Astragalus sect. Incani , which occurs within the area covered by the Flora of Iran. Astragalus wojciechowskianus Ranjbar is described as a new species. A. procerus Boiss. & Hausskn . , A. cottonianus Aitch. & Baker, A. achundovii Grossh., A. orduabadensis Grossh. and A. glaucophyllus Bunge are reported as new records for the flora of Iran .   © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 443–447.     

Microfossils and evidence of land plant evolution

Resolving the question of (1) land plant and (2) vascular land plant evolution is a complex problem. It requires a continued, multidisciplinary effort. We are all grateful to Dianne Edwards and her colleagues (Edwards et al. 1979) for pursuing one such line of research with careful attention to morphology and stratigraphy. Their efforts, however, are confined to one small part of the globe, and they perforce involve only one type of evidence effective with regard to questions of vascular plant evolution once the land estate has been reached. They do not deal with the basic question of vascular and non-vascular land plant origins. The so-called Přídolí benchmark that remained the sine qua nun for vascular plant evolution when Dianne Edwards began her studies has now been irrevocably breached. What other supposedly sacrosanct benchmarks will also crumble as the result of future discoveries, now that vascular plants have been recovered from lower Ludlovian strata? Nevertheless, pre-Devonian plant megafossils are too rare to yield definitive results with regard to the origin of land plants prior to the vascular estate, even though they could in principle (as emphasized by Edwards et al. 1979) provide the least ambiguous evidence. We must look elsewhere than to megafossils for evidence suggesting links in time between green algal ancestors, major groups of living green land Plants, and the many extinct groups of enigmatic higher land plants in the crucial Early Paleozoic time interval.     

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.     

Fossil actinomycete filaments and fungal hyphae in dicotyledonous wood from the Eocene London Clay, Isle-of-Sheppey, Kent, England

Two types of filamentous microfossil are preserved within vessel elements and rays of pyritized and partly carbonized twigs from the Lower Eocene London Clay. The first type, probably a Streptomyces -like actinomycete, is slender (<1 µm) with branches and some regular septation. Wider filaments (>2 µm) are fungal hyphae; no reproductive structures are preserved. These filamentous organisms probably started growing saprophytically after the death of the twigs; the fungi created lysis tracks on cell walls. Both are seen to pass through pyrite crystals that fill the lumina of some vessel elements, showing that they are not Recent contaminants.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 383–394.