Taxonomic Problems (taxonomic + problem)

Distribution by Scientific Domains

Selected Abstracts

Application of nr-DNA ITS sequence for identification of Fusarium culmorum isolates,

EPPO BULLETIN, Issue 3-4 2000
P. K. Mishra
Variation within the internal transcribed spacers (ITS1 and ITS2) and 5.8S ribosomal DNA region of 60 Fusarium culmorum isolates (section Discolor), representing different hosts and diverse geographical origins was examined by polymerase chain reaction (PCR), coupled with sequencing. Phylogenetic relationships of these F. culmorum isolates were estimated in relation to Fusarium spp. from this and other sections of the form-genus, using sequences available from Genbank. The amplified ITS region was approximately 570 bp long in 56 isolates and approximately 585 bp in four other isolates. The inferred phylogeny distinguished clearly four isolates supplied as F. culmorum. These isolates differed in both morphology and sequence from the remaining F. culmorum material. Sequence analysis revealed that the remaining 56 isolates were divided into three ITS types, within which the divergence was extremely low. ITS sequence comparison among the Fusarium isolates showed two major clades, one comprising sections Discolor, Sporotrichiella and Gibbosum and the other comprising Elegans, Liseola, Martiella and Roseum. These results demonstrate the use of the ITS region to resolve the identification and taxonomic problems of Fusarium spp. especially at sectional level but demonstrate the need to develop some other molecular markers for identification at the level of species or race. [source]

Differential Growth Inhibition of Diaporthe and Phomopsis Isolates by the Metabolic Activity of Five Actinomycetes

M. Munta ñola-Cvetkovic
Fifty-five cultures derived from Diaporthe perithecia and Phomopsis pycnidia found on diverse host plant species collected at different times and sites in Vojvodina, Yugoslavia, showed distinguishing quantitative reactions to the fungistatic activity of five actinomycetes obtained as fortuitous laboratory contaminants coming from field material. Streptomyces albidoflavus, S. albus, S. diastaticus, Streptomyces sp., and Streptoverticillium sp. could be ranked by their growth-inhibitory potential, with S. albus showing the strongest, and Streptomyces sp. the lowest. The responses of the fungi varied depending on the tested actinomycetes, but two major groups could be distinguished: A, which encompased the isolates that were less affected by the proximity of the actinomycetes; and B, with those which exhibited high sensitivity in all the experiments. Group A was typically represented by Diaporthe arctii, Phomopsis longicolla, and the Phomopsis type-1 cultures from Xanthiumitalicum; group B was typically represented by Diaporthe/Phomopsis helianthi,Phomopsis type-2 cultures from X. italicum, and isolates from Lactuca serriola. The results obtained underscore the dissimilarities between D. arctii and D. helianthi, and corroborate the value of the physiological aspects of congeneric isolates in considering taxonomic problems in the coelomicete genus Phomopsis. Zusammenfassung Aus Diaporthe -Perithecien und Phomopsis -Pyknidien von verschiedenen Wirtspflanzenarten, die zu unterschiedlichen Zeitpunkten und an verschiedenen Orten in der jugoslawischen Vojvodina gesammelt worden waren, wurden 55 Kulturen gewonnen. Die Isolate zeigten charakteristische quantitative Reaktionen auf die fungistatische Aktivität von fünf Actinomyceten, die im Labor als Zufallskontaminanten auftraten und von Feldmaterial stammten. Streptomyces albidoflavus, S. albus, S. diastaticus, Streptomyces sp. und Streptoverticillium sp. konntenihrem wachstumshemmenden Potential entsprechend geordnet werden, wobei S. albus die stärkste und Streptomyces sp. die niedrigste Hemmung zeigte. Die Reaktionen der Pilze variierten in Abhängigkeit von den getesteten Actinomyceten, doch zwei Hauptgruppen lie,en sich unterscheiden: Gruppe A umf,te die Isolate, die von der Nähe der Actinomyceten weniger gehemmt wurden, und Gruppe B die Isolate, die bei allen Versuchen eine hohe Sensitivität zeigten. Typische Vertreter der Gruppe A waren Diaporthe arctii, Phomopsis longicolla sowie die von Xanthium italicum stammenden Phomopsis -Kulturen vom Typ 1. Typische Repräsentanten der Gruppe B waren Diaporthe/Phomopsis helianthi, die von X. italicum stammenden Phomopsis -Kulturen vom Typ 2 sowie von Lactuca serriola stammende Isolate. Die Ergebnisse verdeutlichen die Unterschiede zwischen D. arctii und D. helianthi und bestätigen die Bedeutung physiologischer Aspekte von Isolaten innerhalb derselben Gattung bei der Betrachtung taxonomischer Probleme in der Coelomyceten-Gattung Phomopsis. [source]

The phylogeny of the Praomys complex (Rodentia: Muridae) and its phylogeographic implications

Among the African Murinae (Rodentia, Muridae), the Praomys complex, whose systematics has been studied by different approaches, has raised numerous taxonomic problems. Different taxa, namely Praomys, Mastomys, Myomys and Hylomyscus have been considered either as separate genera or subgenera of Praomys. In order to understand the relationships within the Praomys complex and to test the monophyly of the genus Praomys, a cladistic analysis was conducted, based on morpho-anatomical factors involving different species of Praomys, Mastomys, Myomys and Hylomyscus. The results indicate that the Praomys complex is monophyletic, as are the genera Hylomyscus, Mastomys and Myomys, whereas the genus Praomys appears paraphyletic. Indeed, a group of species including Praomys jacksoni was found to be more closely related to the genera Mastomys and Myomys than to a Praomys tullbergi -group. The biotopes and the distribution areas of the species were mapped on the phylogeny. It appears that the different clades each present a relative ecological cohesion and are arranged according to a gradient from closed to open habitats. From there, an evolutionary scenario is proposed for the emergence of the different clades and species of the genus Praomys sensu stricto. Phylogénie du complexe Praomys (Rodentia: Muridae) et ses implications biogéographiques Au sein des Murinae africains (Rodentia, Muridae), le complexe Praomys, dont la systématique a étéétudiée par différentes approches, a soulevé de nombreux problèmes taxinomiques. Les différents taxons Praomys, Mastomys, Myomys et Hylomyscus ont été considérés tour à tour comme des genres séparés ou des sous-genres de Praomys. Afin d'appréhender les relations de parentéà l'intérieur du complexe Praomys ainsi que pour tester la monophylie du genre Praomys, nous avons conduit une étude cladistique basée sur la morpho-anatomie, incluant différentes espèces de Praomys, Mastomys, Myomys et Hylomyscus. Les résultats indiquent que le complexe Praomys est monophylétique, comme le sont les genres Hylomyscus, Mastomys et Myomys, alors que le genre Praomys est paraphylétique. En effet un groupe d'espèce incluant P. jacksoni se trouve être plus proche des genres Mastomys et Myomys que du groupe incluant Praomys tullbergi. Les biotopes et les aires de distributions des espèces ont été plaquées sur la phylogénie. Il apparaît alors que les différents clades présentent chacun une relative unitéécologique et sont agencés suivant un gradient des milieux fermés vers les milieux ouverts. A partir de ces résultats, un scénario évolutif, basé sur les oscillations climatiques quaternaires, est proposé pour les différents clades et espèces du genre Praomys sensu stricto. Die Stammesgeschichte des Praomys-Komplexes (Rodentia: Muridae) und deren phylogeographischen Konsequenzen Unter den Afrikanischen Murinen (Rodentia, Muridae) ergaben sich beim Komplex der Gattung Praomys, der bereits in verschiedener Weise untersucht worden war, zahlreiche taxonomische Probleme. Die verschiedenen Taxa Praomys, Mastomys, Myomys und Hylomyscus wurden entweder als verschiedene Gattungen oder als Untergattungen von Praomys angesehen. Um die Verwandtschaftsbeziehungen zwischen den Taxa des Praomys- Komplexes besser verstehen zu lernen und die Frage der Monophylie der Gattung Praomys zu testen, führten wir eine kladistische Analyse unter Verwendung morpho-anatomischer Parameter von verschiedenen Arten von Praomys, Mastomys, Myomys und Hylomyscus durch. Die Ergebnisse zeigen, daß der Praomys- Komplex monophyletisch ist, wenn man die Gattungen Mastomys, Myomys und Hylomyscus betrachtet, während die Gattung Praomys paraphyletisch zu sein scheint. Allerdings erweisen sich einige Arten, Praomys jacksoni eingeschlossen, näher verwandt zu den Gattungen Mastomys und Myomys als zur Praomys tullbergi -Gruppe. Die Biotope und die Verbreitungsgebiete der Arten wurden mit Bezug auf die Phylogenie kartiert. Es zeigt sich, daß jede der verschiedenen Kladen eine relative ökologische Zusammengehörigkeit und einen gegliederten Gradienten von geschlossenen zu offenen Habitaten erkennen läßt. Davon ausgehend wird ein evolutionstisches Szenario für die Entstehung der verschiedenen Kladen und der Arten der Gattung Praomys sensu strictu vorgeschlagen. [source]

Isolation and characterization of microsatellite markers from Sarcocystis neurona, a causative agent of equine protozoal myeloencephalitis

Abstract The population genetics and systematics of coccidian parasites of the genus Sarcocystis remain poorly defined, notwithstanding their relevency to veterinary and human health. Despite opportunities for sexual recombination, nonrecombinant parasite clones characterized by distinct transmission and pathogenesis traits persist in related parasites (i.e. Toxoplasma gondii). In order to determine whether this may be generally true for parasitic coccidia, and to address evolutionary and taxonomic problems within the genus Sarcocystis, we isolated 12 polymorphic microsatellite markers (four to 14 alleles) for Sarcocystis neurona, the major causative agent of equine protozoal myeloencephalitis (EPM). [source]

Examination of the type material of Synedra rumpens =Fragilaria rumpens, Bacillariophyceae

Akihiro Tuji
SUMMARY Fragilaria rumpens (Kütz.) G. W. F. Carlson is assumed to be a cosmopolitan species, and is often reported from ponds and lakes. Nevertheless, this species is similar to both Fragilaria capucina Desm. and Fragilaria vaucheriae (Kütz.) J. B. Petersen and, as a consequence, the taxonomy of all three species has been confusing. In an attempt to solve the taxonomic problems within this group, we have examined the type material of Synedra rumpens and discuss the differences between it and some of those species said to be similar. [source]

The use of volunteers for conducting sponge biodiversity assessments and monitoring using a morphological approach on Indo-Pacific coral reefs

James J. Bell
Abstract 1.Sponges are an important component of coral reef ecosystems, but even though they are widespread with the ability to significantly influence other benthic community members they rarely feature to any great extent in current monitoring or biodiversity assessment programmes conducted by volunteer and professional groups. This exclusion is usually because of the taxonomic problems associated with sponge identification. 2.A potential alternative to monitoring temporal or spatial change in sponge assemblages and assessing biodiversity levels is to characterize sponges using morphologies present rather than collecting species data. Quantifying sponge biodiversity (for monitoring and biodiversity assessments) at the morphological level is less time and resource consuming than collecting species data and more suited to groups with little training and experience of sponge taxonomy or in regions where detailed taxonomic information on sponges is sparse. 3.This paper considers whether the same differences and similarities in sponge richness and assemblage composition can be identified using species and morphological data in response to environmental gradients at two coral reef ecosystems in south-east Sulawesi, Indonesia, and whether volunteers can be used to reliably collect morphological information. Sponge morphologies were classified into 14 groups and different morphological assemblages were found by the author at the two sites and between depth intervals. Comparisons of sponge species and morphological composition data showed that common patterns in assemblage structuring and richness could be identified irrespective of whether morphological or species data were used. In addition, a positive linear relationship was found between sponge species and morphological richness. 4.The morphological data recorded by volunteer divers (n=10) were compared with that collected by the author. Although volunteers recorded fewer sponges than the author (approximately 15% less), missing mainly small encrusting specimens, similar assemblage structure could be identified from both the volunteers' and the author's data. 5.The results showed that the same differences in sponge assemblages between sites and depths could be identified from both species and morphological data. In addition, these morphological data could be reliably collected by volunteer divers. Copyright © 2006 John Wiley & Sons, Ltd. [source]

A re-assessment of the taxonomy of Lens Mill. (Leguminosae, Papilionoideae, Vicieae)

Three taxonomic problems exist within the genus Lens. The first is the lark of agreement on classification and rank at the specific and sub-specific levels; the second involves the relationship between the recently distinguished L lamottei and L odemensis or L tomentosus and the third is the unreliability of stipule orientation as the primary character to distinguish between L odemensic and L. nigricans. The objectives of this study were to address these problems by investigating the classification of Lens in the light of evidence relating to crossability and phenetic relations, to idcntify morphological markers for taxon delimitation within the genus Lens., with special reference to L. lamottei, L nigricans and L odemensis, and to determine whether the taxon delimitation is supported by isozyme and RAPD evidence. As a result of these studies two new combinations are proposed, with L odemensis and I tamentosus being reduced to sub-species of L culinaris. A classification, key and descriptions of the accepted taxa within the genus are presented. [source]