| 1. |
- Zamora, Juan Carlos, et al.
(författare)
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Considerations and consequences of allowing DNA sequence data as types of fungal taxa
- 2018
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Ingår i: IMA Fungus. - : INT MYCOLOGICAL ASSOC. - 2210-6340 .- 2210-6359. ; 9:1, s. 167-185
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Tidskriftsartikel (refereegranskat)abstract
- Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.
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| 2. |
- Du, Xi-Hui, et al.
(författare)
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Cytological studies reveal high variation in ascospore number and shape and conidia produced directly from ascospores in Morchella galilaea
- 2023
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Spores are important as dispersal and survival propagules in fungi. In this study we investigated the variation in number, shape, size and germination mode of ascospores in Morchella galilaea, the only species of the genus Morchella known to fruit in the autumn. Based on the observation of five samples, we first discovered significant variation in the shape and size of ascospores in Morchella. One to sixteen ascospores were found in the asci. Ascospore size correlated negatively with ascospore number, but positively with ascus size, and ascus size was positively correlated with ascospore number. We noted that ascospores, both from fresh collections and dried specimens, germinated terminally or laterally either by extended germ tubes, or via the production of conidia that were formed directly from ascospores at one, two or multiple sites. The direct formation of conidia from ascospores takes place within asci or after ascospores are discharged. Using laser confocal microscopy, we recorded the number of nuclei in ascospores and in conidia produced from ascospores. In most ascospores of M. galilaea, several nuclei were observed, as is typical of species of Morchella. However, nuclear number varied from zero to around 20 in this species, and larger ascospores harbored more nuclei. One to six nuclei were present in the conidia. Nuclear migration from ascospores to conidia was observed. Conidia forming directly from ascospores has been observed in few species of Pezizomycetes; this is the first report of the phenomenon in Morchella species. Morphological and molecular data show that conidial formation from ascospores is not found in all the specimens of this species and, hence, is not an informative taxonomic character in M. galilaea. Our data suggest that conidia produced from ascospores and successive mitosis within the ascus may contribute to asci with more than eight spores. The absence of mitosis and/or nuclear degeneration, as well as cytokinesis defect, likely results in asci with fewer than eight ascospores. This study provides new insights into the poorly understood life cycle of Morchella species and more broadly improves knowledge of conidia formation and reproductive strategies in Pezizomycetes.
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| 3. |
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| 4. |
- Healy, Rosanne, et al.
(författare)
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Competing sexual-asexual generic names of Pezizomycetes and recommendations for use.
- 2016
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Ingår i: IMA Fungus. - Ingenta : Springer Science and Business Media LLC. - 2210-6340 .- 2210-6359. ; 7:2, s. 285-288
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Tidskriftsartikel (refereegranskat)abstract
- Following the change that eliminated dual naming of sexual and asexual morphs of fungi, generic names of Pezizomycetes have been evaluated to determine which of the competing names should be recommended for use. Evaluation is based on congruence of type species to determine if the names are congeneric and which name is most commonly cited as well as priority. In the Pezizomycetes six pairs of generic names were determined to compete. In all cases the older name, representing the sexual morph, is recommended for use, specifically Caloscypha rather than Geniculodendron, Desmazierella rather than Verticicladium, Miladina rather than Actinosporella, Morchella rather than Costantinella, Sarcoscypha rather than Molliardiomyces, and Trichophaea rather than Dichobotrys.
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| 5. |
- Sundberg, Henrik
(författare)
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Contributions to the understanding of diversity and evolution in the genus Coreomyces
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Laboulbeniales is an order of enigmatic ascomycete fungi that are obligate microscopic parasites of arthropods, which are usually non-detrimental. They typically display a high degree of host specificity, and the genus Coreomyces, which is the recurring theme of this thesis, is no exception. Coreomyces is a small aquatic genus parasitising water boatmen (Corixidae). Members in this genus present something that is unique for Laboulbeniales, position specificity. This means that a parasite is restricted to a specific position on the host. This thesis aims at elucidating the patterns of host and position specificity present in the genus Coreomyces by the use of molecular markers. A second aim is to describe new taxa encountered during the course of the project. Finally we wanted to reveal what mating system is present in a member of the Laboulbeniales, something that has never been done before. Understanding the mode of sexual reproduction and to get insights into mating type organisation can give important clues to how the species patterns we observe may have evolved. To achieve these goals we first had to develop a robust and simple molecular methodology that made use of as little material as possible, preferably a single thallus. Our results showed that position specificity indeed exists in this genus, but that it is not as strict as previously presumed, all species we analysed occupied more than one position. Further we were able to show that thalli found in the same position on different hosts constitute the same species, and also that two sister species utilise the same position. We conclude that, in most cases, growth position is more important than host species or host sex in species delimitation. We confirmed the presence of four discrete taxa, two of which were described as new species, Coreomyces confusus H. Sundb. et al. and C. dextrorsus H. Sundb. et al. Finally we were able to show that C. macropus and C. confusus are likely to display a homothallic breeding system.
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