Taxonomic and morphological relationships of the psilotaceae: Introduction to the symposium

This symposium was organized to publicly discuss the controversy over the relationships of the Psilotaceae, centering around Bierhorst’s thesis thatPsilotum andTmesipteris are filicalean ferns.     

Apigenin and amentoflavone glycosides in the psilotaceae and their phylogenetic significance

Documentation of amentoflavone O-glucosides as the predominant flavonoid glycosides in both genera of the Psilotaceae clearly distinguishes this family from all other families of vascular plants. Psilotum and Tmesipteris also possess apigenin C- and O-glycosides as common flavonoid types. Apigenin 7-O-rhamnoglucoside occurs in both genera and the previously undocumented apigenin 7-O-rhamnoglucoside-4′-O-glucoside, although identified only in Tmesipteris, may also be present in Psilotum. The existence of flavone C-glycosides in both genera may provide a phytochemical relationship between the Psilotaceae and some ferns. The phylogenetic significance of these results is discussed.     

Morphologic and taxonomic relationships of the Psilotaceae relative to evolutionary lines in early land vascular plants

Examination of the fossil record shows that there is no direct evidence regarding the origins and early evolution of the Psilotaceae. Past comparisons betweenPsilotum orTmesipteris and certain fossil plants are reviewed. The major types of early land vascular plants are surveyed in order to demonstrate their basic characteristics and evolutionary trends and to point out the absence of any direct links with the Psilotaceae. Fossil plants of problematical affinities which appear to be important in the early diversification of ferns or plants closely related to ferns are discussed. The nature of stem-leaf relationships of some primitive, extant filicalean ferns and possibly the Psilotaceae is considered in terms of possible similar occurrences among fossil plants.     

Fossils and ferns in the resolution of land plant phylogeny

Fifty-two taxa of living and extinct vascular plants were evaluated in an unconstrained numerical cladistic analysis using 101 morphological characters to simultaneously resolve the phylogenetic relationships of ferns sensu lato. Included in the analysis were ferns assignable to the Cladoxylales, Stauropteridales, Rhacophytales, Zygopteridales, Ophioglossales, Marattiales, Filicales, and Hydropteridales, as well as a rhyniophyte, a trimerophyte, equisetophytes, lignophytes, and the psilotophytesPsilotum andTmesipteris. The results placed ferns and fernlike plants in three distinct clades, indicating that ferns s.l. are a polyphyletic grade group. Fern clades consist of extinct stauropterids; extinct cladoxylaleans, rhacophytaleans, and zygopteridaleans; and eusporangiates and leptosporangiates with living and extinct species. Psilotophytes occur near the base of the tree rather than nesting with the Filicales, as hypothesized by some. These results place Ophioglossales as the sister group to Marattiales plus the leptosporangiates, supporting the hypothesis that Ophioglossales represent ferns rather than progymnosperms. These analyses are a first attempt, which includes extinct plants, to develop cladistic hypotheses for the overall topology of fern phylogeny and to lay the groundwork for more detailed analyses of relationships among the homosporous leptosporangiates.     

Alkanetriols in psilotophyte cutins

The covalently bonded components of the stem cutin of Psilotum include 16-hydroxyhexadecanoic acid and substantial amounts of hexadecane-1,8,16-triol. While of generally similar composition, leaf cutin of Tmesipteris contains a mixture of hexadecanetriol isomers. The findings suggest that psilotophyte cutins evolved in a different manner from those of other land plants.     

ON PHENOTYPIC EXPRESSION,MORPHOGENETIC PATTERN AND SYNANGIUM EVOLUTION IN PSILOTUM

Both the typical form and the appendageless variant of Psilotum nudum produce terminal synangia at the ultimate tips of the aerial axes. One clone in particular of the typical appendaged form produced synangia entirely at the tips of the aerial branches, as in the appendageless variant, and also developed occasional lateral transitional entities on the upper aerial axis displaying appendagelike and axislike morphological qualities. A developmental comparison of synangium development at the ultimate tips of aerial branches and of unusually elongating and normal sized fertile-appendages showed that the morphogenetic pattern of synangium development was similar. Anatomical and morphological evidence showed the synangium to be derived from terminal subdivisions or bifurcations of the apical meristem of each structure studied. This supports the phyletic concept that the synangium of the Psilotaceae is basically terminal to an axis or an axis homologue, and that it probably evolved from terminal bifurcative branching. Occasional multiple sporangium lobes may be formed on a P. nudum synangium which may not be represented by vascular bundles. Two hypothetical phyletic models of synangium evolution are proposed that could be used to explain this phenomenon and which should be tested by further evidence. Typical and appendageless P. nudum were compared in their morphogenetic pattern developed at the upper axis vegetative apical meristem, and a reconciliation was made between the structuring of the apparently disparate forms, which involved the presence or absence of serial ordering in apical derivatives. It is suggested that this could serve as a model for appendage evolution in the family Psilotaceae.     

Experimental and Analytical Studies of Pteridophytes: XXXVII. A Note on the Inception of Microphylls and Macrophylls

In an attempt to shed new light on the nature of microphyllsand macrophylls, a study has been made of leaf inception inselected materials, including Psilotum, Tmesipteris and otherpteridophytes, and flowering plants such as Cuscuta with greatly‘reduced’ leaves. It is shown that the incipientprimordia of the small scale-like leaves of Psilotum and ofthe quite substantial, though microphyllous, laminate leavesof Tmesipteris are closely comparable and that there are noessential differences in the histological organization of incipientmicrophylls and incipient macrophylls. In parasitic speciessuch as Cuscuta, with small scale-like leaves, the organizationof the apical meristem and the inception of primordia are asin normal autotrophic species. The so-called ‘reduced’leaves and the microphyllous condition of some pteridophytesare attributable to a physiological-genetical limitation ofgrowth of primordia in the subapical regions of the shoot. Theconclusions which may be drawn from these observations are discussed.     

Taxonomic reexamination of the two species of blue-green algae,Calothrix scopulorum andC. crustacea

The taxonomic relationship between the 2 marine blue-green algae,Calothrix scopulorum andC. crustacea, which are considered to be conspecific by some authors, is discussed based on the statistical investigation of morphology with field and culture materials and on the phenological investigation. The presence or absence of intercalary heterocyst in the filament cannot be always used as a clear taxonomic character to distinguish the 2 species, judging from the result of culture experiment. However, it is confirmed that there are morphological differences between the two in the length of filament, the diameters of filament, trichome, hair, heterocyst and hormogon and the seriation of heterocyst in the filament, and that there are also ecological differences between the two in the color of plant, the tidal level of growth, the period of growth and the season of hormogon formation. From these facts it is concluded thatC. scopulorum andC. crustacea should be treated as separate species.     

Neue Sutnerien-Funde aus Ostafrika Ihre Bedeutung für Taxonomie und Phylogenie der Gattung

New Sutneriids from Eastern Africa (Ethiopia, Djibouti and Tanzania) are described and their phylogenetic relations discussed; one species is new, three are mentioned first time from Eastern Africa. During the taxonomic studies it became evident that a revision of the old european speciesS. cyclodorsata andS. eumela should be included as those species have been interpreted in different ways since the last century. Therefore it was inevitable to restudy the types and further material. Forms not belonging to these species as defined by the types have been described asS. hoelderi andS. lorioli nom. nov.     

Taxonomic affinities ofPhysena (Physenaceae) andAsteropeia (Theaceae)

Asteropeia andPhysena are both enigmatic woody dicotyledons from Madagascar. Various taxonomic affinities have been suggested for both genera, but no consensus has been reached. An analysis of rbcL sequence data strongly supports recognition of the sister-group relationship ofAsteropeia andPhysena and their placement as the sister group to Caryophyllales. Many similarities were noted betweenAsteropeia andPhysena for stem, wood, leaf, flower, pollen, and fruit characters. The most notable differences are found in the morphology of the flowers and the anatomy of the wood rays.     

Atlas of foliar surface features in woody plants,V. fraxinus (Oleaceae) of eastern North America

Scanning electron microscopy of foliar surfaces of the seven species ofFraxinus native in eastern North America confirms the importance of cuticular patterns (smooth, striated, striate-papillose, and coronulate) as useful taxonomic character states. There are there trichome types (acicular hairs ornamented with micro-striae or-papillae, peltate glands, and scales) which are found in nearly all species and which vary only in density. No differences in surface features are found by which determination can be made of either sex or ploidy level inF. americana. Hybridization betweenF. americana andF. pennsylvanica is considered to be rare in nature and is not a probable cause for the overlap of character states and concomitant difficulty of identification based upon gross morphological features. Likewise, the putative hybrid origins ofF. biltmoreana andF. profunda are not supported by micro-morphological features. Illustrations are given for all species.     

Refractive spherules in phloem ofMicrosorium scolopendria andPsilotum nudum

Summary Phloem tissues ofMicrosorium scolopendria (Polypodiaceae) andPsilotum nudum (Psilotaceae) were examined with light and electron microscopes. The characteristic refractive spherules in the sieve elements ofM. scolopendria apparently develop from endoplasmic reticulum-derived cytoplasmic vesicles. In both taxa they have not been observed to be spatially related to plastids or mitochondria. Refractive spherules contain protein and often occur in the peripheral cytoplasm of mature sieve elements. InM. scolopendria they also occur in pericycle cells. Significant differences in refractive spherule substructure occur between the two taxa studied.     

Rearranged labdane diterpenoids from Galeopsis angustifolia

From the aerial part of Galeopsis angustifolia collected in Spain, a labdane and three rearranged labdane diterpenoids have been isolated. The structures of these new substances have been established by chemical and spectroscopic means and by correlation with known compounds. A sample of the same species collected in Italy and other species of Galeopsis showed some remarkable chemical differences. The taxonomic significance of these results is discussed briefly.     

The arthropodsmimetaster andvachonisia from the devonian hunsrück shale

A combined X-ray/surface study ofMimetaster andVachonisia has revealed several new features.Mimetaster has a head with stalked eyes and ocelli, a ventral organ, a large labrum, and two pairs of strong uniramous legs revealing muscle strands. The body carries up to more than 30 pairs of bifid appendages.Vachonisia, without visible eyes, appears to have three pairs of walking legs on the head. Two pairs of structures directed towards the mouth may be strong endites or discrete manipulating appendages. The body carries about 80 pairs of appendages, which are bifid and similar to those of Mimetaster. Both arthropods have one pair of antennae.Mimetaster seems to have been a deposit feeder,Vachonisia a carnivore or raptator. The former was related toMarrella, and these two probably toVachonisia, all of which may have been distantly related to the trilobite-chelicerate group.     

Scanning electron microscopy of cultures of rare macromycetous fungi

Using scanning electron microscopy it was possible to describe structures on the mycelia of macromycetous fungi that possess both taxonomic and functional importance. For taxonomic characteristization of 11 studied species, the presence and distribution of clamps on hyphæ represent an, important feature; in the case ofLyophyllum decastes the form of clamps may be useful for identifying cultures. Formation and types of anamorhps inPleurotus calyptratus, Montagnea arenaria andLyophyllum decastes are also of taxonomic importance. For additional taxonomic characterization of cultures ofTricholoma mongolicum the formation of “coils” might be exploited. Formation of anastomoses and crystals has predominantly a physiological role. However, in our view, production of crystals under certain culture conditions may serve as a diagnostic parameter.     

The biology ofSclerotinia sclerotiorum,S. trifoliorum,andS. minor with emphasis on specific nomenclature

The separation ofSclerotinia sclerotiorum (Lib.) de Bary, 5.trifoliorum Erikss., andS. minor Jagger into three distinct species has been based on traditional morphological and physiological criteria such as gross cultural characteristics, sclerotial size, ascus and ascospore dimensions, time of apothecial development in the field, and host association. However, these characteristics tend to be variable and some workers have concluded that the three fungi should be included in one species, 5.sclerotiorum. Recently, new data have been published on morphological, cultural, physiological, ontogenetic, enzyme pattern, mycelial interaction, and cytological characteristics of isolates ofSclerotinia spp. This information supplements, but does not replace, that available from more traditional taxonomic methods and helps to resolve the controversy on the taxonomy and nomenclature of these fungi. This article reviews the relevant literature on the biology of 5.sclerotiorum, S. trifoliorum, and 5.minor, with particular emphasis given to those differences between them that could be of significance regarding their specific nomenclature. After an introduction, mycelia, microconidia, sclerotia, apothecia, infection, control, and taxonomy and nomenclature are discussed. The authors conclude thatS. sclerotiorum, S. trifoliorum, andS. minor are distinct species. The characteristics used to distinguish between them are summarized in table form.     

Diversity of developmental patterns in achelate lobsters—today and in the Mesozoic

Modern achelate lobsters, slipper and spiny lobsters, have a specific post-embryonic developmental pattern with the following phases: phyllosoma, nisto (slipper lobsters) or puerulus (spiny lobsters), juvenile and adult. The phyllosoma is a peculiar larva, which transforms through a metamorphic moult into another larval form, the nisto or puerulus which largely resembles the juvenile. Unlike the nisto and puerulus, the phyllosoma is characterised by numerous morphological differences to the adult, e.g. a thin head shield, elongate appendages, exopods on these appendages and a special claw. Our reinvestigation of the 85 million years old fossil “Eryoneicus sahelalmae” demonstrates that it represents an unusual type of achelatan lobster larva, characterised by a mixture of phyllosoma and post-phyllosoma characters. We ascribe it to its own genus: Polzicaris nov. gen. We study its significance by comparisons with other cases of Mesozoic fossil larvae also characterised by a mixture of characters. Accordingly, all these larvae are interpreted as ontogenetic intermediates between phyllosoma and post-phyllosoma morphology. Remarkably, most of the larvae show a unique mixture of retained larval and already developed post-larval features. Considering the different—and incompatible—mixture of characters of each of these larvae and their wide geographical and temporal distribution, we interpret all these larvae as belonging to distinct species. The particular character combinations in the different larvae make it currently difficult to reconstruct an evolutionary scenario with a stepwise character acquisition. Yet, it can be concluded that a larger diversity of larval forms and developmental patterns occurred in Mesozoic than in modern faunas.     

A re-evaluation ofBlayacina Cobbold 1932 andThoralaspis Hupe 1953 (Trilobita: Redlichiida)

The monotypic trilobite generaBlayacina andThoralaspis from the late Early Cambrian of the Montagne Noire, Southern France, are revised. Restudy of the type specimens and of new material from the type locality and stratum as well as morphometric measurements strongly support the assumption that both taxa are identical and that morphologic as well as taxonomic differences resulted from tectonic distortion. Thus,Thoralaspis thorali has to be regarded as a subjective junior synonym ofBlayacina miqueli andThoralaspis as a junior synonym ofBlayacina. Its systematic position as a morphologic group aroundLusatiops within the Ellipsocephalidae-Protoleninae is confirmed.