The structure and evolution of Ordovician conodont apparatuses

Multielement taxonomy was instituted for Ordovician conodonts over a decade ago, and probably a majority of the multielement genera have been defined or are well understood. The present systems of notation for elements within apparatuses are inadequate and cumbersome. A new notation scheme is proposed which applies a single-letter code to the position in the apparatus occupied by certain element morphotypes. The taxonomic status of all known Ordovician conodont genera is reviewed (appendix) using the new notation, and a new scheme to classify conodont apparatuses is presented. Five main apparatus types (I-V) and seventeen subtypes (IA-IC, etc.) are defined. Within these groups, all known Ordovician conodont genera can be accommodated, and probably few new groups are required to include all other conodont genera. The apparatus types and subtypes are defined on the basis of symmetry, curvature, and number of the element types, with a clear distinction being made between the first and second transition series. Certain homologous relationships, both between and within many apparatus types, are noted. The evolution of the five major types, and the subtypes, is traced through the Ordovician. The pattern of evolution suggests that the types and subtypes recognized are probably natural biologic groupings, largely reflecting phylogenetic change.     

ELEMENT ARRANGEMENT IN CONODONT APPARATUSES OF HINDEODELLA TYPE AND IN SIMILAR FORMS

The criteria used for logical and numerical reconstruction of conodont apparatuses are: (1) Similar stratigraphical and geographical occurrence. (2) Similar frequency variation. (3) Similar appearance of details in the conodont-elements. (4) Similar composition of the conodont apparatuses.
The position of conodont-elements in some types of apparatuses, as reconstructed by Lange (1968), is supported by further evidence, and it is also possible to reconstruct the precise position of certain elements. It is probable that a great number of apparatuses with compound conodont elements consisted of homologous elements and that a reconstruction of the positions of the elements from cluster material can be generalized to include all these apparatuses. From the periphery inwards, a complete apparatus of this type consisted of ne, hi, hi, pl, and tr elements and, posterior to these, of pairs of oz and sp elements.     

国产酸浆属（茄科）的叶表皮和种皮特征及其分类学意义

在光学显微镜和扫描电镜下观察了茄科酸浆属５种２变种及邻近属２种植物：辣椒和龙珠的叶表皮及种皮特征,发现上述植物的叶上、下表皮细胞表面观形状为不规则形,垂周壁浅波状、波状或深波状;一些类群的气孔器在上、下表皮均存在,另一些类群的气孔器则仅在下表皮存在,其类型一致为无规则型。扫描电镜下叶下表皮的特征,包括角质膜以及气孔外拱盖和拱盖内缘的特征,有一定的分类学价值。此外,种皮纹饰可作为区分酸浆属、辣椒和龙     

Conodont affinity of the enigmatic Carboniferous chordate Conopiscius

Conopiscius shares V-shaped myomeres with the co-occurring conodont Clydagnathus but instead of a complex oral apparatus it has only a single pair of conical elements, and structures resembling scales are associated with its myomeres. Moreover, the coarsely crystalline crown tissue typical for conodonts has not been identified in the Conopiscius elements, which show only a finely lamellar skeletal tissue. The gap between conodonts and Conopiscius may be filled by isolated elements of similar morphology and structure occurring in the Late Devonian. They reveal a very thin external layer developed mostly at the tooth tip and resembling conodont crown tissue. The pulp cavity is partially filled with layered or spherulitic phosphatic tissue of the kind known also in conodonts (basal filling tissue) and early vertebrates (lamellin). Conodont elements of similar morphology and representing uni-membrate oral apparatuses have not been previously reported from the Devonian or Carboniferous but occur near the Cambrian–Ordovician transition ( Proconodontus ) and in the Late Permian ( Caenodontus ). It is proposed that Conopiscius represents a mostly cryptic conodont lineage extending from the Early Ordovician to the Permian, instead of being directly related to the agnathans.     

菊科莴苣族6属11种植物的叶表皮形态

在光学显微镜下观察了菊科莴苣族6属11种植物的叶表皮形态,观察了叶上下表皮细胞形状及垂周壁式样、气孔器类型和分布特征。结果表明：这些植物的叶上下表皮细胞多数为不规则形,少数为多边形;垂周壁式样多数为浅波形或深波形,少数为平直形。一些种类气孔器仅分布在下表皮,但也有不少种类上下表皮都有气孔器分布。气孔器都属于无规则型,且都是随机分布。叶表皮显微构造在一定程度上能反映出类群间的关系,为探讨莴苣族的分类学问题提供了新的证据。     

A Light and Scanning Electron Microscopic Study of the Closing Apparatus in Tintinnid Ciliates (Ciliophora,Spirotricha, Tintinnina): A Forgotten Synapomorphy

ABSTRACT. A membranous closing apparatus shuts the lorica opening in disturbed tintinnids of six genera belonging to four families. The homology of the apparatuses is investigated, using data from the literature and Mediterranean tintinnids studied in vivo and by scanning electron microscopy. Morphological and functional similarities indicate that the foldable closing apparatus is not only a synapomorphy of the genera Codonella (Codonellidae) and Dictyocysta (Dictyocystidae), as suggested 80 years ago, but also of Codonaria (Codonellidae) and Codonellopsis (Codonellopsidae). In Codonaria, Codonella, and Dictyocysta, the apparatuses merge posteriorly into membranous lorica sacs, which probably represent homologous structures. The diagnoses of these genera are improved according to the new findings. The close relationship of Codonella, Codonellopsis, and Dictyocysta is also inferred from small subunit rRNA phylogenies and the ultrastructure of the capsules. It contradicts the current lorica‐based classification of the tintinnids. The assumption that the diaphragm‐like apparatus in the genera Salpingacantha and Salpingella is not homologous to the foldable ones in the genera mentioned above is supported by molecular and cytological features.     

金星蕨科16种植物叶表皮特征的研究

利用光学显微镜对金星蕨科(Thelypteridaceae)8属16种植物的叶表皮形态进行了观察和研究,为金星蕨科植物的系统演化及分类提供科学依据。结果表明:(1)16种金星蕨科植物的叶片表皮细胞为不规则型,表皮细胞垂周壁大多呈深波状。(2)气孔为下生型,多呈椭圆形;共观察到6种气孔器类型(极细胞型、腋下细胞型、聚合极细胞型、聚腋下细胞型、不规则型和聚围绕细胞型),每种植物具2~5种不同类型的气孔器。(3)金星蕨科8属植物在表皮细胞大小、垂周壁形状、气孔大小和形状、气孔密度、气孔指数和气孔器类型上存在一定的属间差异。     

Patterns of bilateral asymmetry and allometry in Late Devonian Polygnathus conodonts

Conodont animals were early jawless vertebrates equipped with a feeding apparatus composed of several tooth‐like elements. The P1 elements, at the rear of the apparatus, were characterized by a robust shape and rapid morphological evolution. Occlusion occurred between paired right and left P1 elements, occasioning some bilateral asymmetry, which, together with allometric growth, may partially obliterate the temporal differences. The present study aims to disentangle these different components of morphological variation in Late Devonian Polygnathus P1 conodont elements. An extensive 2D geometric morphometric analysis of the platform shape was performed through the Famennian record of two outcrops. This analysis was completed by a 3D study on a subset of conodont elements. The 2D and 3D morphometric quantifications provided highly congruent results, showing that the 2D shape constitutes a good approximation of the element geometry. The 3D analysis delivered further insights into the relationship between the geometry of the elements and the constraints related to occlusion. The 2D analysis allowed a quantitative assessment of the variation among species and through time. Allometry and bilateral asymmetry were differently expressed depending on the species considered, suggesting that constraints imposed on pairing by the morphology of the elements varied even among related species. The within‐species variation was so important that it largely obliterated temporal trends; a relationship of Polygnathus shape and conodont biofacies variations through the Famennian nevertheless suggested an evolution driven by ecological interactions between conodont genera.     

Conchodontus,Mitrellataxis and Fungulodus: Conodonts,fish or both?

Conchodontus, Mitrellataxis and Fungulodus are phosphatic microfossils from the Late Devonian of China and North America, alternatively interpreted as conodont elements or fish scales. The histology and microornament of these sclerites have been studied in an attempt to resolve their affinity, and to determine characters for distinguishing between conodont elements and the ichthyoliths of other lower vertebrates. The histology of all three genera is directly comparable to conodont elements, dispelling the notion that conodonts are histologically indistinguishable from the teeth and scales of other vertebrates. Microornament is found not to be useful in discriminating between high-level taxonomic groupings. White matter and thickness of prismless enamel are suggested as apomorphies of the Conodonta.     

Parafurnishius,an Induan (Lower Triassic) conodont new genus from northeastern Sichuan Province,southwest China and its evolutionary implications

A fundamental aspect of taxonomy at the generic level, critical to understand Early Triassic conodont evolution, is the composition of the multielement apparatus. In this paper, we document a platform-bearing new conodont genus, Parafurnishius n. gen., as well as its multielement apparatus from the Griesbachian Feixianguan Formation (Lower Triassic) in Xuanhan County, northeastern Sichuan Province, southwest China. The new conodont genus is characterized by numerous robust and irregularly distributed conical denticles with variable platform morphology that has a possible affinity with the P₁ elements of Furnishius. These genera have apparatuses similar to those of Ellisonia and are classified with the family Ellisoniidae. The strong intraspecific variation of P₁ elements and the growth series within the entire sample population suggest that Parafurnishius may have evolved from the Griesbachian Isarcicella by developing random denticle positioning away from the platform centre, and then possibly evolved into younger Triassic Furnishius by developing a stable blade configuration. This preferred interpretation implies an ellisonid apparatus for Isarcicella. Alternatively, Parafurnishius may have evolved from Ellisonia and developed a homeomorphic P₁ element with Isarcicella. This new taxon has strong intraspecific variation of denticle growth orientation during the Early Triassic.     

Maximum axial root growth pressure in pea seedlings: effects of measurement techniques and cultivars

Values of the maximum axial growth pressure (σ_max) of seedling pea (Pisum sativum L.) roots reported in the literature, obtained using different apparatuses and cultivars, range from 0.3 MPa to 1.3 MPa. To investigate possible reasons for this large range, we studied the effect of apparatus and cultivar on measurements of σ_max in peas. We describe four types of apparatus which can be used to measure axial root growth force and hence σ_max, and used them to measure σ_max in seedling pea roots using cultivar Meteor. Two of these apparatuses were also used to compare σ_max for three pea cultivars (Helka, Meteor and Greenfeast). Both cultivar and apparatus significantly affected σ_max , but there were greater differences between apparatuses than between the three cultivars. Estimating root cross-sectional area from the diameter of cross-sections, rather than from in situ measurements (i.e. measurements made with the root still in place in the apparatus) may explain these differences. This revised version was published online in June 2006 with corrections to the Cover Date.     

Molecular phylogeny of ciliates: What does it tell us about the evolution of the cytoskeleton and of developmental strategies?

An rRNA phylogeny of 22 species of ciliates belonging to seven of Small and Lynn's eight classes has been obtained by distance and parsimony methods. It displays good congruence with classical systematics at low taxonomic levels and several major surprises at higher levels: (1) The species analyzed group into five major branches, four of which emerge almost simultaneously: hypotrichs, oligohymenophorans, lito-stomes, and nassophoreans corresponding to four of Small and Lynn's classes. The simultaneous emergence of these groups contradicts the long accepted view that litostomes (a group with “simple”, symmetrical, apical oral apparatus) are “primitive,” while hypotrichs are “highly evolved.” (2) Heterotrichs group with a karyorelictid, together forming the first emerging branch. While this supports the view that karyorelictids may be early-emerging ciliates, it completely explodes the traditional “spirotrichs” taxon, which united heterotrichs and hypotrichs. Instead, this reinforces the concept of Postciliodesmatophora and suggests that asymmetric oral apparatuses (i.e., with distinct paroral and adoral ciliatures) may be primitive in ciliates. The global topology of the tree therefore does not fit with the classical views of ciliate evolution, from “simple” oral apparatus and stomatogenesis to “complex” ones. Instead, a rather striking agreement with the strategy adopted to construct the cortical framework was disclosed. We noted that the cytoskeletal elements used to strengthen the cell surface could be subdivided into four main types: epiplasm, filaments, continuous microtu-bules, or basal body derived fibers. These four types fitted quite well with the major evolutionary lines disclosed by the molecular phylogeny. We therefore discuss unorthodox hypotheses assuming an early explosive radiation of ciliates into a small number of major lineages differing essentially in the solution adopted to subtend the cell surface and anchor the infraciliature. © 1992 Wiley-Liss, Inc.     

Zur Biologie, Taxonomie und Chronologie der Conodonten

The actual state of knowledge concerning the conodont animal is critically reviewed. All soft tissue documented by the specimens of the conodont animal were interpreted by the British collectors as Craniota (Vertebrata) features. Opinions on the precise affinities, however, remain controverse: The alleged chorda could have been a gut, bilateral symmetry, myomery, apatitic biomineralisation occur also in Invertebrata, caudal fins do in Chaetognatha. Even the lobes in the capital area interpreted as sensory organs could have served as aiding organs for food intake. Therefore, the originally sensational findings are reduced to the core issue that the conodont animal had an eel-like body and at the blunt end of it, behind peculiar lobes, the mineralized conodont elements were arranged. As a consequence, a relationship to the Protochordata cannot be excluded. A systematic position of the conodont animal as possible Vertebrata is likely only if organized below the Ostracodermata which is particularly so because conodonts occur so early in the Cambrian. In the second part of the article conodonts are discussed as guide fossils. The comprehensive, empirically grown taxonomy of the single elements is the prerequisite for recognizing outstanding, high resolution stratigraphy. In comparison, a multielement taxonomy remains as long problematical, as it is based on assumed, mostly statistically reconstructed rather than on natural multielement apparatuses. Taxonomical and nomenclatorial operations built on assumed apparatus affinity can bear heavily on nomenclature and stratigraphy of platform elements. It can be shown at the example of the Devonian that the platform elements have provided particularly in the pelagic facies a Standard Conodont Zonation that covers time almost without any gaps. The basis for this is that platform single element species and their phylogenetic development are extra-well known. In a special paragraph, history and applicability of the Standard Zonation is discussed in details. Different conodont biofacies are developed between the pelagic realm where the Standard Zonation originated, and the coastal areas so that conodonts can indicate temporal and bathymetric relationships of the mother rocks. In addition alternative conodont zonations were introduced mainly for the shallow water. Because of their conspicuous stratigraphic significance in the Devonian, conodonts were employed by International Committees to redefine Series and Stage Boundaries. For the boundary selection species were utilized from phylognetic lineages as only from tight evolution their point of origination could be well identified and recognized in worldwide correlation. The GSSPs (Global Stratotype Section and Point) within the Devonian are discussed in detail. In recent times, attempts are made at calibrating the duration of conodont zones on the basis of their well known rate of evolution and high temporal resolution. These analyses have to be continued in order to demonstrate the absolute time relationship of condont zones in more and continuous detail. Currently the phyletically controlled Standard Conodont Zonation is the authoritative stratigraphic method in the Devonian. It has provided together with the GSSPs precise and valuable fix points for a Global Time Scale (GTS). In combination with additional stratigraphie methods the Standard Conodont Zonation may provide further refinements in the future.     

THE FLAGELLAR APPARATUS OF ENTOCLADIA VIRIDIS MOTILE CELLS,AND THE TAXONOMIC POSITION OF THE RESURRECTED FAMILY ULVELLACEAE (ULVALES,CHLOROPHYTA)1

The flagellar apparatuses of the quadriflagellate zoo-spores and biflagellate female gametes of the marine chaetophoracean alga Entocladia viridis Reinke are significantly different from those of algae belonging to Chaetophoraceae sensu stricto, but closely resemble those of ulvacean genera. These differences permit the taxonomic reassignment of certain marine chaetophoracean genera and an evaluation of the flagellar apparatus features used to characterize the class Ulvophyceae. Critical features of the zoospore include arrangement of the four basal bodies into an upper and a lower pair with the proximal ends of the upper basal bodies overlapping, terminal caps, proximal sheaths connected to one another by striated bands, and a cruciate microtubular rootlet system having a 3-2–3-2 alternation pattern and striated microtubule-associated components that accompany the two-membered rootlets. An indistinct distal fiber occurs just anterior to the basal bodies, and is closely associated with the insertion into the flagellar apparatus of the three-membered rootlets. The flagellar apparatus demonstrates 180° rotational symmetry, and its components show counterclockwise absolute orientation when viewed from above. Newly described features include the prominently bilobed structure of the terminal caps on the upper basal body pair, and the presence of both a granular zone and an additional single microtubule anterior to each of the four rootlets, an arrangement termed the “stacked rootlet configuration.” Rhizoplasts were not observed and are presumed to be absent. The gamete is identical, except for the absence of the lower basal body pair and the presence of an electron-dense membrane associated structure that resembles the mating structure found in Ulva gametes. These findings, correlated with life history data, sporangial and gametangial structure and developmental patterns, chloroplast pigment arrays, and vegetative cell ultrastructural features, compel the removal of Entocladia viridis and similar members of the marine Chaetophoraceae to a separate family, the Ulvellaceae. The latter is referred to the order Ulvales of the Ulvophyceae. The counterclockwise absolute orientation of components, and terminal caps, may be the most consistent flagellar apparatus features of ulvophycean green algae, while variations in other features previously considered diagnostic for the Ulvophyceae may serve instead to identify discrete lineages within this class.     

Structural deviations in the prothoracic tracheal apparatuses of the armoured ground crickets,Acanthoplus speiseri Brancsik., and Enyaliopsis cf. matebelensis Per. (Orthoptera: Tettigoniidae,Hetrodinae) from the ‘typical’ Hetrodinae condition of Zeuner (1936a) and their importance to tettigoniid classification

Prothoracic tracheal apparatuses of Acanthoplus speiseri Brancsik and Enyaliopsis cf. matebelensis Per., are described. The vesicula femoralis for the apparatus of each species differs from the condition considered by Zeuner (1936a) to be typical for the subfamily Hetrodinae to which the two species belong. Acanthoplus speiseri possesses a horn-shaped apparatus, while E. cf. matebelensis bears a trumpet-shaped structure. The horn-shaped prothoracic tracheal apparatus was previously reported to be a specialized structure in the ‘Bradyporoid group’ of Zeuner (1936a). The trumpet-shaped apparatus is reported for the first time in the subfamily. The problems of using the prothoracic tracheal apparatus as a taxonomic character in classifying the tettigoniid subfamilies and the implications of the presence of the atypical prothoracic tracheal apparatuses in the Hetrodinae to the classification of the Tettigoniidae are discussed.     

Characters of Leaf Epidermis and Their Systematic Significance in Menispermaceae

The epidermal characters of mature leaves of 29 genera, 50 species and 3 varieties (totally 56 samples) representing all the 5 tribes in the family Menispermaceae were examined under the light microscope. The main conclusions are as follows: (1) The shape of the epidermal cells is polygonal or irregular, and the anticlinal walls are straight or waved in the family. In some genera a special arrangement of epidermal cells is named as “rosette-cell arrangement" for the first time. The lower epidermal cells were found to have a papilla in Stephania, Diploclisia and Legnephora . (2) In some genera, the anticlinal walls are oblique, rather than perpendicular, to the surface. (3) The stomatal apparatuses, generally restricted to the lower surface of the leaves, were assigned to anomocytic, staurocytic, cyclocytic, anisocytic and actinocytic types, and their distribution on the epidermis may be of diffuse pattern or island congregating pattern. (4) The cells of both upper and lower epidermis in the tribe Pachygoneae and Fibraureae are generally polygonal with straight or arched anticlinal walls, and the stomatal apparatuses are usually staurocytic and actinocytic. The cyclocytic stomatal apparatus was found only in two genera of the tribe Pachygoneae. By contrast, the epidermal cells of the tribes Anomospermeae, Tinosporeae and Menispermeae are generally irregular with waved anticlinal walls, and the stomatal apparatuses are predominantly anomocytic. These correlated characters are of much significance in delimiting tribes within the Menispermaceae, and also provide evidence for studies on systematic relationships of several genera.     

天南星科叶表皮研究

利用光学显微镜对天南星科18属27种及菖蒲科1属1种植物的叶表皮微形态进行观察,同时用扫描电镜对具代表性的14种植物作了研究,结果显示：天南星科气孔类型变异较大,有不规则型,辐射型,平列型,胞环型及平列型和胞环型间的过渡类型,副卫细胞数目0－12个;表皮细胞长宽近相等,平周壁具条纹或否,垂周壁平直,弧形或波浪形,虽然气孔类型对天南星科分类上的意义不大,但与表皮细胞垂周壁形状,副卫细胞角质层纹饰等特征相结合对种间分类有一定意义,天南星科与菖蒲科叶表皮微形态明显不同,从而支持菖蒲属从天南星科中分出另立为科的观点。     

Functional changes in the anatomy of the pharyngeal jaw apparatus of Astatoreochromis alluaudi (Pisces, Cichlidae), and their effects on adjacent structures

Organisms are tightly packed with structures so architectonic interdependency of structures is an obvious aspect of integration. This aspect of functional morphology, however, has received remarkably little attention. The present paper presents an example of the spatial relations among several apparatuses in the head of the cichlid fish, Astatoreochromis alluaudi. It investigates the transformations of these apparatuses and their functions due to a change in the pharyngeal jaw apparatus resulting from a functional shift (insect eating to snail crushing or vice versa ). The volume of the pharyngeal jaw apparatus differs 55% between the insect eating- and the snail eating morph. The increase in volume of the pharyngeal jaw apparatus has an impressive number of spatial effects, both direct and indirect, on other structures. Reallocation of space within the pharyngeal jaw apparatus occurs. Total head volume increases 31% but a reallocation of space is still necessary as the increase of the opercular compartment where the pharyngeal jaw apparatus is situated compensates for only 59% of the volume increase of that. Not all spatial effects do impose constraints. Spatial constraints are avoided when one of the apparatuses can use a topographically different volume of space. The respiratory apparatus shows internal reallocations of space without loss of total volume. The same solution occurs for elements of the expansion apparatus and the buccal savity. The eyes are not influenced. Finally spatial effects can have positive repercussions. The muscles of the oral jaw apparatus increase in size. This may be an example of an epiphenomenon.     

Early Triassic conodont clusters from South China: revision of the architecture of the 15 element apparatuses of the superfamily Gondolelloidea

Abstract: Several fused clusters of conodont elements of the genera Neospathodus and Novispathodus were recovered from limestone beds at the Dienerian–Smithian and Smithian–Spathian boundaries, respectively, from several localities in Guangxi province, South China. Conodont clusters are otherwise extremely rare in the Triassic, and these are first described for the Early Triassic. The exceptional specimens partially preserve the relative three‐dimensional position and orientation of ramiform elements and are therefore extremely important for testing hypotheses on the architecture of apparatuses. These specimens partly confirm the previous reconstruction of the Novispathodus apparatus by Orchard. Within apparatuses of members of superfamily Gondolelloidea, elements previously identified as occupying the S₁ and S₂ positions instead occupy the S₂ and S₁ positions. Similarly, within apparatuses of members of the subfamily Novispathodinae, elements previously referred to S₃ and S₄ positions are reinterpreted to have occupied S₄ and S₃ positions, respectively.