A new species of Ceratozamia (Zamiaceae) from Tabasco and Chiapas, Mexico

Ceratozamia becerrae sp. nov. is described and illustrated. This species from Tabasco and Chiapas has affinity with C. miqueliana H. Wendl. from Veracruz and Chiapas, but differs in morphology and habit of leaves, leaflets, male and female strobili and trunk. Ceratozamia becerrae is considered part of the C. miqueliana species complex that includes C. miqueliana, C. euryphyllidia Vázq.Torres, Sabato & Stevenson and C. zoquorum Pérez-Farrera, Vovides & Iglesias. The geographical range of this species complex is southern Veracruz, Tabasco and northern Chiapas in tropical rain forests.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 123–128.     

A new species in the genus Dioon (Zamiaceae) from north-central Oaxaca, Mexico

Dioon argenteum sp. nov. (Zamiaceae) is described from northern Oaxaca, México. Flat leaves, and persistently tomentose, slightly imbricate leaflets with marginal prickles characterize this species. The specific epithet argenteum was chosen to describe the silver appearance of the persistent tomentum covering the new leaves. D. argenteum appears to have affinities with D. purpusii and D. califanoi.   © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 141 , 471–476.     

Two new species of Galium (Rubiaceae) from the Iberian Peninsula

Two new species of the genus Galium are described from the Iberian Peninsula: G. moralesianum Ortega-Olivencia & Devesa, and G. talaveranum Ortega-Olivencia & Devesa. The first grows on limestone or dolomitic-limestone outcrops in south-east Spain (the Segura and Gádor mountain ranges) and shows morphological similarities with G. boissieranum Ehrend. & Krendl, which is endemic to southern Spain (mountains of Málaga). The second inhabits the margins of water courses, alder stands and cork-oak dehesas (parkland-type systems) of the west of the Iberian Peninsula, and is morphologically reminiscent of G. mollugo L. The chromosome numbers of these two species and of G. boissieranum are given.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 177−187.     

Two new South American species of Struthanthus (Loranthaceae) posing a challenge to circumscription of neotropical genera

Two new, closely related species of Struthanthus (Loranthaceae) are described, S. meridionalis from southern Bolivia and S. prancei from northern Brazil, each showing significant deviations from the generic norm in their inflorescence morphology. In both cases, a very high proportion of inflorescences bear bracteolate and/or ebracteolate monads as lateral units rather than the triads which characterize the rest of the genus. The place of inflorescence morphology in the development of generic concepts in small-flowered neotropical Loranthaceae is briefly reviewed, leaving the two new species in Struthanthus for the time being.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 469–474.     

Studies on Thapsia (Apiaceae) from north-western Africa: a forgotten and a new species

Following a revision of Thapsia (Apiaceae) in north-western Africa, the name Thapsia platycarpa is resurrected and lectotypified for a species that grows between Algeria and Morocco, and a new species Thapsia cinerea is described from the Rif region of north-eastern Morocco. Morphological features that differentiate between these and other species ( T. villosa , T. garganica , T. transtagana and T. gymnesica ) are discussed. An identification key for the plants of the area is presented.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 433–442.     

A new species of Scorzonera L. (Asteraceae) from south Anatolia, Turkey

A new species Scorzonera gokcheoglui O. Ünal & R. S. Göktürk sp. nov. from south Anatolia is described and illustrated. Its relationships with S. argyria and S. pisidica are discussed. A map showing the distribution of the species and other related species is given.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 465–468.     

Morphological and geographic variation of the cycad Dioon edule Lindl. (Zamiaceae): ecological and evolutionary implications

The relationship in geographical distribution and morphological variation of leaflet width and length (diagnostic trait), between and within populations of Dioon edule Lindl., has been investigated throughout its known range in eastern Mexico (from the states of Nuevo León to Veracruz, north to south, respectively). A total of 1832 leaflets were measured for width and length from 154 plants distributed amongst five populations using four leaflet replicas from each of three leaves per plant. For leaflet width and length the variation among populations indicated significant stat-istical differences ( F _4,147 = 125.83; P  < 0.0001; R ² = 92.17% and F _4,147 = 9.04; P  < 0.001; R ² = 26.8%), respectively. With respect to leaflet width, the multiple range test showed three groups with a north to south distributional relationship along the range of the species. The correlation coefficient among paired populations, respect to geographical distance and the absolute value of the mean difference of leaflet width in each population, was positive, and different from zero ( r  = 0.82; P  = 0.013). A great variation of important ecological and evolutionary parameters was shown.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 141 , 465–470.     

The marginal band, a new structural component of the developing angiosperm leaf

The marginal band, a newly described structure of the dicot leaf, plays an essential role in the formation of this organ. It arises along the two edges of a leaf as several files of adaxial epidermal cells during the peg stage of ontogeny. Functionally, it appears to serve as the prepattern for a number of secondary features including (i) the marginal growth meristem present in all leaves as seen in mountain laurel, (ii) rows of lobes and spines as in Salvia and Ilex , (iii) pigmentation as in some cultivars of Hydrangea , (iv) propagation as in the plantlets of Kalanchoe pinnata , (v) marginal ridges for support in a few varieties of Viburnum and Ilex , and (vi) marginal necrosis as in Strelitzia for blade partitioning.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 21–28.     

A new species of Silene (Caryophyllaceae) from South Anatolia, Turkey

Silene doganii A.Duran & Y.Menemen sp. nov. from the Amanos Mountains (C6: Osmaniye-Turkey) is described and illustrated. It is closely related to S. caramanica Boiss. & Heldr., from which it differs mainly in its habit, hairiness, leaf and floral features.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 109−113.     

Arbuscular mycorrhizal fungi: genetics of multigenomic, clonal networks and its ecological consequences

Arbuscular mycorrhizal fungi are thought to have remained asexual for 400 million years, although recent studies have suggested that considerable genetic and phenotypic variation could potentially exist in populations. A brief discussion of these multigenomic organisms is presented.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79 , 59–60.     

Molecular and morphometric data demonstrate the presence of cryptic lineages among freshwater crabs (Decapoda: Potamonautidae: Potamonautes) from the Drakensberg Mountains, South Africa

The evolutionary importance of cryptic taxa is well documented, yet few studies have examined them with a view to conservation. In the present study, the significance of cryptic speciation in freshwater crabs is examined. Allozyme and 16S rRNA sequence data were used to explore the degree of population differentiation between mountain stream populations of two distinct freshwater crab species. Marked patterns of differentiation were evident among populations; those in close geographical proximity were characterized by the fixation of alternate alleles at certain loci, indicating that currently there is no gene flow among populations. Both allozyme and sequence data provide evidence for the recognition of at least five distinct evolutionary lineages with pronounced levels of genetic differentiation. Morphometric data failed to detect any distinct geographically intermediate population groupings. Our findings indicate the presence of five phylogeographical units, all worthy of conservation, three of which are evolutionarily significant.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78 , 129–147.     

Phylogenetics, zoogeography, and the role of dispersal and vicariance in the evolution of the Rana catesbeiana (Anura: Ranidae) species group

The Rana catesbeiana species group consists of seven species, each variously distributed across eastern North America. We estimated the evolutionary relationships among 31 exemplars and used the phylogenetic hypothesis to examine the potential modes of speciation and relative role of dispersal in the evolution and zoogeography of this species group. Phylogenetic relationships based on 1554 combined base pairs of the cytochrome b and ND2 mitochondrial genes suggest that the species are closely related, having undergone rapid radiation from a common ancestor during the late Miocene or Pliocene. A Pleistocene origin for the rare R. okaloosae is suggested by its pattern of paraphyly with R. clamitans and by its geographically restricted distribution, although hybridization as the explanation for paraphyly cannot be ruled out. Dispersal–vicariance analysis suggested a Coastal Plain biogeographical region origin of the species group, supporting the notion that the region was an important centre of anuran diversification, with post-speciation dispersal playing a major role in explaining the distribution of the widespread species, R. catesbeiana , R. clamitans, and R. septentrionalis . High sea levels during the late Tertiary, greatly reducing and insularizing parts of the southern Coastal Plain region may have played a major role in the diversification of this group.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 601–624.     

Minuartia graminifolia (Caryophyllaceae), a south-east European species

A re-evaluation of Minuartia graminifolia has been undertaken based on comparative morphological studies. M. graminifolia subsp. rosani (an endemic of the south-central Apennines and Sicily) and subsp. hungarica (an endemic of the Banat region of Romania) are accepted infraspecific taxa. M. graminifolia subsp. hungarica is lectotypified. M. graminifolia subsp. clandestina is confirmed for Italy; the taxon is neotypified. The type subspecies is considered an endemic to the east-central Alps. Keys to the species of Minuartia ser. Graminifoliae and to the subspecies of M. graminifolia are provided.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 419–432.     

Weintrauboa, a new genus of pimoid spiders from Japan and adjacent islands, with comments on the monophyly and diagnosis of the family Pimoidae and the genus Pimoa (Araneoidea, Araneae)

The spider genus Weintrauboa new genus (Araneae, Pimoidae) is described to place two species of pimoids from Japan and adjacent islands that were formerly classified in the linyphiid genus Labulla . Weintrauboa contortipes (Karsch) new comb., the type species, and W. chikunii (Oi) new comb. are redescribed. Parsimony analysis of morphological characters provides robust support for the monophyly of the genus Weintrauboa and corroborates the monophyly of Pimoa , Pimoidae, and the clade Linyphiidae plus Pimoidae. New diagnoses for Pimoa and Pimoidae are provided.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society , 2003, 139 , 261–281     

Astragalus neo-assadianus (Fabaceae), a new species in sect. Alopecuroidei from Iran

Astragalus neo-assadianus (Fabaceae), a new species endemic to Iran, is described and illustrated. This species belongs to A. sect . Alopecuroidei and is distinct and interesting among the Iranian species. It is confined to the north-eastern part of Iran (Khorasan Province) and only known from a single collection close to the Turkmenistan frontier.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 197–200.     

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.     

A new species of Valantia (Rubiaceae) from Spain

A new species of Valantia , V. lainzii Devesa & Ortega-Olivencia, endemic to the coastal zone of Granada (southern Spain) is described. The species recalls V. muralis L. in its general aspect, and V. deltoidea Brullo in the type of fructiferous body.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 331–335.